| Author | Message | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 630 Registered: 1-2003 Posted From: 67.142.130.37 Rating: |
OK, we've been on the road for a full day since our in-frame at PEDCO, and we still have at least one problem still with us. Before I get to that, thanks to everyone who helped with the problems thus far, including sources for the fuel pressure switch. And, to everyone who has inquired about the in-frame, how we fared at PEDCO, and what the original source of that problem was, please check our blog. I will post the information over there later tonight, just so I don't have to type it all in three places. Now, as for the ongoing problems: we are still overheating. Originally, I thought that the overheating, black smoke, and low power were all related. The low power and the smoke were easily explained by the fact that the engine was "dirted out." This is a condition in which dirt particles have entered the engine through the air induction system, and, over time, have worn the cylinders smooth and the rings loose, just like sandpaper. After enough of this, the rings no longer make a good seal, resulting in low compression (thus the lack of power) and excessive blow-by (thus the smoke). The engine has now been completely rebuilt, at least as far as can be while still in the frame. So I have eight new cylinders, pistons, and ring sets, two completely rebuilt heads, a rebuilt turbo, and all new bearings. Also, four of the eight injectors were replaced, since they tested marginal. So, in theory, I have an essentially new engine. Nevertheless, we are still having a tremendous heat problem. Now, the 8V92TA is probably the most heat-producing automotive engine ever built, and we've always had to slow down for the grades to keep the engine temps in the black. But this is beyond the pale -- today, climbing Union grade from Laughlin to Kingman, a 12-mile, 6% affair, we had to slow down to 15mph in first gear, and, even then, I had to pull over and stop twice, where the high-idle still took close to ten minutes to bring the temperature back down into the 190's. So something is still amiss. With that background, here are my questions: (1) Can this be something other than a cooling system issue? In other words, can there be some sort of, for example, combustion problem that is generating all this excess heat? I am particularly worried about this because, during the rebuild, they found one cylinder with seized rings. With different injectors and new liner, rings, and valves, it's hard for me to imagine what sort of problem could have existed before the rebuild that could be still with us, but, please, educate me. (2) I am hoping that this is just a cooling system issue, that developed independently of the other problems. In which case, I have to guess that the three most likely possibilities are thermostat problems, water pump problems, or radiator problems. Where would you start, and what methods would you use to isolate the problem further? (3) I am further guessing that the thermostats are OK, since I see the same temps on both sides of the block with my IR gun, and the temp eventually drops, under no-load, to 180 or so and stays there. Does that make sense? (4) I suspect the water pump. That's because turning on my hydronic system's engine pre-heat pump *seems* to have helped (it's hard to say without truly objective data, meaning multiple load runs under identical conditions) a small bit. So here's the $64K question: is there a way to confirm this suspicion without removing it? (5) What is involved in R&R on the water pump? I don't have a Detroit manual (other than the DDEC troubleshooting guide), so please don't just cite page numbers. I'm already guessing I'm going to have to drain several gallons of coolant (shame we didn't look at this while the motor was still empty), but how hard is it to get to the impeller? Thanks in advance for any and all help. -Sean http://OurOdyssey.BlogSpot.com | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 69 Registered: 1-2007 Posted From: 65.61.96.82 Rating: N/A |
Sean, Since I know zero about how your power train is laid out some basic things I would look at. I would sweep the radiator with your IR gun working from inlet tank to outlet tank working back and forth across the radiator core to see if there are any hot or cold spots. Also take note of the inlet and outlet temps. Outlet hot, core not working or not moving enough air. Outlet cool, poor coolant circulation. Perhaps someone who has their bus on the road could give us an idea of what normal inlet and outlet temps are after a good run or hill climb. Another busnut had an impeller fail not long ago. Is the tranny temp normal, ie not contributing excess heat load? Is your fan direct drive? Is there any chance the rad core is holding onto some dirt from your off road adventures? Too bad you had to take it easy on the hills. Would have been an ideal place to work it hard to start the break in. The dyno break in that is detailed in the back of my DD manual is an eye opener. Good luck and hope you get back to normal without too much 'sweat'. | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 22 Registered: 10-2006 Posted From: 76.223.83.13 Rating: N/A |
If a thermostat fails they will stick open not closed. How hot did you get it? Ours shuts down automaticly before it gets to 200. | ||
| Jerome Dusenberry (Jerry32)
Registered Member Username: Jerry32 Post Number: 35 Registered: 1-2007 Posted From: 148.78.243.50 Rating: N/A |
The two major thing are the water pump and the radiator. If you thermostat and louvers are working then the radiator flow may be bad. age may have slowed the amaount of flow. since the problems existed before the in frame it 's not likely to have been created by it. Jerry | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1050 Registered: 12-2000 Posted From: 74.12.77.82 Rating: N/A |
HEY! Thermostats can not be counted on to fail open! They will fail however they like, and in an 8V92, I have heard of many in charter service that stuck partially, not opening fully, which made finding them difficult or impossible away from the big hills. New engine, install new thermostats as a matter of course, says I. Easy and cheap before messing with that water pump? happy coaching! buswarrior | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 245 Registered: 8-2006 Posted From: 207.231.81.129 Rating: N/A |
Morning Sean, Is your electric dash temp reading the same as a mechanical gauge in the engine room? Do you have a way of finding Delta T across the radiator and the engine? Needless to say, a high T indicates low flow. Don makes a good point on radiator temps. If the outlet is cool, the rad is rejecting all the heat it is being given, before it gets all the way thru, meaning low coolant flow. If the outlet is hot, low air flow. I hope you aren't running over about 40% Glycol? How is your fan driven/controlled? Put in your earplugs, go back and rev it up hot. If the fan doesn't blow lots of hot air all over you, the drive is the problem. (I remember your post about having the rad cleaned.) An off the wall thought! How much coolant flow is going thru the house portion of the system? Could you be returning a large amount of hot water to the inlet side? Good luck, George (Message edited by George Mc6 on August 05, 2007) | ||
| Dale and LaShawn Hendricks (Lamichelle37)
Registered Member Username: Lamichelle37 Post Number: 6 Registered: 1-2004 Posted From: 72.178.75.83 Rating: N/A |
Sean, you may need to bleed the cooling system of air. Air can get trapped in the system while filling it , causing the overheat problems. Also David Anderson on one of the other boards had numberous problems with overheating on his 6v92 in an Eagle that he finally solved with an updated fan. Dale | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 694 Registered: 10-2003 Posted From: 71.58.117.21 Rating: N/A |
I believe your problems now and before were from excess heat, which could score cylinders similar to dirt. You might use a mister system as a temporary help. How long have you had this coach? Could this problem have been there with previous owner? Maybe that radiator is too small. Is this engine the one that was in it origionally;or was it smaller or less horsepower? I hope that you haven't damaged the rebuild from the overheating. Does the radiator have a shroud that the fan fits fairly close to the opening? Also remember that a newly rebuilt engine is going to generate a greater amount of heat for the first few hundred miles as the rings wear in to the new cylinders. Diesels in general generate the most heat when they are working the hardest, as more fuel is added to the incoming air, and almost no fuel at idle, which is why idling will allow it to cool down, unlike a gasoline engine. What was the outside temp at the time? Have you considered doing the long mountains at night if practical? I think you have a radiator capacity or fan/airflow problem, unless this didn't use to be a problem. Misters are the easiest and cheapest fix for this in the meantime if that is what is causing overheat. Just my thoughts from afar, as I don't know all the above specifics. I do admire your coach- that thing is awsome though. Oh, what is your radiator size and core thickness- just the tube and fin area and thickness. We could then compare it to what the guys are using in an Eagle with this engine. | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 417 Registered: 11-2005 Posted From: 63.97.117.39 Rating: N/A |
Sean, You could have a collapsing hose. Pretty common with autos and really maddening to diagnose. After the engine is good and hot check the hoses with the engine at high rpm. An open thermostat will make the engine run hotter, not cooler, contrary to old wive's tales. I would take it back to the overhauler before it is damaged and let them figure it out, it may be something they did. Probably not since it is ever present, but you spent too much money to take a chance on it. | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 633 Registered: 1-2003 Posted From: 67.142.130.38 Rating: N/A |
(1) Just to be clear, no, this was not a problem "before" -- whenever that might be. I can't say when it started. (2) Nothing that I can "see" is wrong -- no hoses collapsed, no problem with fans, shrouds, radiators, etc. (3) Excess heat, while a possible reason for cylinder damage, would not explain dirt in the airbox, or silicates in the oil. The engine was dusted -- separate (I hope) problem. (4) Going back to PEDCO is not really an option now. We will need to have a shop in Albuquerque, or maybe Santa Fe look at it. Another round trip to PEDCO from here would be $300 in diesel alone, and, since we had this problem before the rebuild, it's not clear that they had anything to do with it. I'll spend the $300 here first, and we'll go back to PEDCO if we find a rebuild-related problem (like a shop towel stuffed into the radiator hose -- don't laugh, you know it's happened before). Lots of good suggestions here. Unfortunately, I am not equipped to follow up on most of them -- I don't even have a place to drain some of the coolant. So I will be looking for a shop somewhere on our way east to drain the coolant, and maybe pull the impeller. I'm estimating well over $1,000 just to get the radiators out far enough to look inside, so I am hoping it's not a radiator issue. Hard to tell with the IR gun -- looks like a several degree drop across each one. They've only got 100K on them, but, then, they are 18 years old, and who knows what kind of junk the PO might have put in the cooling system. -Sean http://OurOdyssey.BlogSpot.com | ||
| Jerry Liebler (Jerry_liebler)
Registered Member Username: Jerry_liebler Post Number: 269 Registered: 3-2005 Posted From: 75.117.211.167 Rating: N/A |
Sean, What have you done to get the induction 'plumbing' cleaned out and prevent more dirt issues? You mentioned the turbo rebuild, was the blower done too? Have you inspected all the induction air plumbing? Others have solved overheating problems by getting cool air into the engine. You may have an open pipe somewhere that's causing the engine to breath in hot air. I guess my point is the overheating could be due to low effective compression due to induction restriction, blower 'slop' or breathing hot air so don't spend all your energy on the coolant flow and radiator air flow. Is your radiator fan drive working properly? Did the radiator really get cleaned out or is there still some airflow restriction in it? The temp change accross the radiators seems small indicating air flow issues. Regards Jerry 4107 1120 | ||
| Dale and LaShawn Hendricks (Lamichelle37)
Registered Member Username: Lamichelle37 Post Number: 7 Registered: 1-2004 Posted From: 72.178.75.83 Rating: N/A |
Sean, Check the radiator caps. I had a heat problem on two different vehicles that was due to bad gasket inside the radiator cap. Changed the radiator in one and had the same overheat problem. Used cap off of old radiator. Put on new cap . Temps normal and no more problem. Dale | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 634 Registered: 1-2003 Posted From: 67.142.130.22 Rating: N/A |
Jerry, The induction plumbing is (and was) good. The dirt got past a bad filter (see the blog for details). The air intake comes through the sidewall of the coach -- no way to get hot air there. If the plumbing comes apart (gulp) it will be downstream of the filter. The blower was cleaned and inspected, I think they decided it did not need to be rebuilt. I'll have to go back to the invoice to check. The radiator did get cleaned -- I watched them do it. And the fan drives seem fine. All the plumbing is now the way it has always been, so I am looking for a new problem. -Sean http://OurOdyssey.BlogSpot.com | ||
| James Stacy (Jimstacy)
Registered Member Username: Jimstacy Post Number: 86 Registered: 1-2001 Posted From: 75.40.249.131 Rating: N/A |
Sean, Are you running an automatic transmission? Allisons are notorious for generating heat by a slightly slipping clutch. Higher power would make it slip more. BTDT. Water pump is gear driven, right on the rear of the engine in an MCI T drive. I am not sure if yours' is different. There are two basic types, "standing" and "walking". This refers to the two "legs" coming out the bottom. They are parallel to each other, or at an angle to each other. DDs are famous for slippage in the main fan drive. If this is oil or water temp controlled check for function. Rubber lined harmonic drives also slip. Garry Dean would only use a straight metal drive for the fan. Too much trouble with the hubs and clutches he claimed. Fan shrouds must be in place and a close fit to the blade tips. They can often be left off at rebuild time. DD two strokes seem to put most of their heat into the coolant, four strokes into the exhaust. Original Detroits in buses were detuned with small injectors and turbos & did not generate a lot of heat. We "improve' them with larger injectors and higher output turbos, generating way more heat than the bus engineer planned for. I hope this gives you some more ideas. Jim Stacy | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 420 Registered: 11-2005 Posted From: 63.97.117.13 Rating: N/A |
Sean, I probably wasn't clear on the collapsed hose or maybe you already know. A hose usually only collapses with the engine hot and at high rpm. It will look perfectly normal at idle or lower rpms. | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 84 Registered: 8-2006 Posted From: 74.32.88.185 Rating: N/A |
Sean,a friend of mine had the K&N filter he had bought from Donnie it came apart and plug the intake pipe and he was lucky that it would not make enough rpms to shift the 740 transmission.I have heard that Donnie has passed away | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 635 Registered: 1-2003 Posted From: 67.142.130.42 Rating: N/A |
Jim, The Allison being the source of the excess heat was also one of my thoughts. But I did have PEDCO drop the pan and remove the valve body, and all was well (other than a leaky 4-way, which they replaced). I elected not to have the tranny pulled altogether and bench-tested -- would a clutch-slip problem show up in a pan-off inspection? Also, would it not be the case that a slipping clutch would show up only in one gear selection? The fans and shrouds were not touched during the rebuild. I have two fans (and two radiators) and they are belt-driven off the crankshaft pulley. No controls at all, just centrifugal clutches. I do know where the water pump is -- I just don't know how to get to the impeller. Is it a simple matter of removing the cover, or is there more involved? Gus: I did understand about hoses collapsing. I really only have one hose that's even long enough -- the others are all just a couple inches. I don't see any problems, but, then, I can't be looking while the coach is under load. Luvrbus: Yes, I've heard Danny passed away as well. Sad -- he was so young. -Sean http://OurOdyssey.BlogSpot.com | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 465 Registered: 7-2006 Posted From: 66.217.102.52 Rating: N/A |
I haven't downloaded this, but would it be of any help to you? Detroit Diesel Cooling System Technician's Guide Re: "I have two fans (and two radiators) and they are belt-driven off the crankshaft pulley. No controls at all, just centrifugal clutches. " Some centrifugal clutches have "lock up" positions. Do those? Can you lock them to insure the fans are spinning at the proper rate? | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 636 Registered: 1-2003 Posted From: 67.142.130.42 Rating: N/A |
John, I have the 7se390 publication. I can't see any kind of lock mechanism on the fan hubs. Frankly, I am only guessing about the centrifugal clutches, because the fans freewheel when the engine is not turning, but seem to be running at normal speed when it is. -Sean http://OurOdyssey.BlogSpot.com | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 467 Registered: 7-2006 Posted From: 66.217.102.52 Rating: N/A |
I'm probably dwelling too much on the "centrifugal clutch" thing, but I've had a vehicle that damned near wore me out with an overheating problem that only presented itself during normal highway speeds. The fan clutch (in that vehicle's case) was designed to "free-wheel" at high speed. I guess the engineers figured that a fan wasn't needed when the wind is going through the front of the vehicle at 60 mph? It would save fuel, not to have to power the fan! Well.... The fan clutch wasn't working properly, and it was almost impossible to detect. A pal suggested locking up the spring that controls the slippage. Once done, the fan ran continuously, and the overheat problem was gone. I eventually replaced the fan clutch and settled it once and for all. I wonder if any of that is similar to your situation..... | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 637 Registered: 1-2003 Posted From: 67.142.130.42 Rating: N/A |
Hmm, maybe it's time to get one of those optical tachs -- I could tach the fan pulleys and then the fans themselves and make sure they are spinning at the same speed... -Sean http://OurOdyssey.BlogSpot.com | ||
| Muddog16 (Muddog16)
Registered Member Username: Muddog16 Post Number: 356 Registered: 11-2004 Posted From: 4.224.243.8 Rating: N/A |
No load temps running normal might indicate as Gus mentioned hoses collasping under high load conditions! 20 year old radiators could be a problem and that depends on how the coolant was treated over a period of time, you could have a blockage in serveral passes limiting the efficiency of the radiators. Pedco has a very good reputation through the boards! The water pump is very cheap and simple to replace if you have direct access. Sean do you have a dual cooler assembly, one cools the engine the other cools the transmission? If the engine was full of dirt before the rebuild, did they clean both coolers, my guess being external they probably didn't but i could be wrong, just something else to check! The cooler is on the left hand side of the engine block as your looking from the rear of the bus at the engine. You could also check your transmission lines to the cooler with your temp gun! Good luck! Pat | ||
| Muddog16 (Muddog16)
Registered Member Username: Muddog16 Post Number: 357 Registered: 11-2004 Posted From: 4.224.243.8 Rating: N/A |
Sean, I have some photo's of my engine out of the bus showing the water pump and dual cooler if that may help locating them! Pat http://prevostlemirage.blogspot.com/ | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 70 Registered: 1-2007 Posted From: 65.61.96.82 Rating: N/A |
Sean, Sounds like it is hard to get a good temp reading at the rads. Since you can't tell yet if it is an engine, water pump, thermostat problem or a radiator or air flow problem, one way to isolate it would be to put a temp gauge on the engine coolant inlet. Then take on a hill and see what the temp difference between outlet and inlet is. Don't know if you can learn much shooting the temp while standing still. I don't know what the options are for monitoring the temp of a inlet line are, but it would be cheaper than a rad rebuild that may not be needed. Is there is a way to do it without dropping the coolant? Don't know if there are contact types readily available. There are temp probes for many of the better multi-meters. Being the redneck mechanic that I am, lacking anything better, I would take a regular temp gauge, your choice between mechanical or electric, and tie it on the inlet pipe line far enough before the engine to be sure the engine is not affecting the readout, then wrap it up with insulation. Maybe even wet it down to help transfer the heat. Check the accuracy with you IR gun. Do you have a rear temp gauge or can the DDEC readout confirm that you dash gauge is telling you the truth? Even if it turns out to be rad problems, I would change the thermostats for sure and water pump just for peace of mind while you have the system open. I would even consider putting in a permanent inlet temp gauge or at least a bung to put one in for future trouble shooting. Good luck Don 4107 | ||
| Leland Bradley (Lee_bradley)
Registered Member Username: Lee_bradley Post Number: 17 Registered: 11-2006 Posted From: 138.163.0.42 Rating: N/A |
Sean, You said you have centrifugal clutches. Are sure you don't have viscous fan drives? The viscous drives sense the air temperature and increase the shaft to fan coupling as the temperature increases. These can fail. Your idea of a tach to check the relative speed is a good idea. | ||
| Leland Bradley (Lee_bradley)
Registered Member Username: Lee_bradley Post Number: 18 Registered: 11-2006 Posted From: 138.163.0.38 Rating: N/A |
Sean, Horton builds a number of visous fan drives including one that is controlled by the engine management system. http://www.hortonww.com/products/products.asp | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 638 Registered: 1-2003 Posted From: 66.82.9.54 Rating: N/A |
Well, we're parked out in front of Stewart & Stevenson, the Detroit distributor here in Albuquerque. I hoped to have them do a quick cooling system diagnosis, but they can't get me in to the shop until late tomorrow at the earliest, and maybe later than that. So my next question is: Can anyone recommend another shop here in Albuquerque, or maybe in Santa Fe (our next stop)? As for the fan drives, I guess they could be viscous couplings -- how would I tell by looking? Failing getting any resolution here, my next step is to pull the grade to Santa Fe. I am guessing I will need to pull over to cool down at least once, and I know from experience that it will take several minutes. Plenty of time to go back and shoot some temps. So here is another question: What's a "normal" drop across the radiators? Say, for example, that I am reading a coolant temp of 200 on the DDEC -- what should I expect the radiator inlet and outlet temperatures to be at high-idle (~1,000 rpm)? BTW, I have two identical radiators and fans, and the coolant flow is simply split between them. And no service was done on the tranny or oil coolers, as they are below the level of things that need to come off the block during an in-frame. Lastly, anyone know where I can pick up an optical tach in this area? I really don't want to wait for mail-order, or deal with figuring out where to send it. -Sean http://OurOdyssey.BlogSpot.com | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 422 Registered: 11-2005 Posted From: 63.97.117.16 Rating: N/A |
Sean, Load is not the determinate for collapsing hoses, rpm is. This is not theory, I've experienced it a few times. If you can turn the fans with engine off they are viscous. (Message edited by gusc on August 06, 2007) (Message edited by gusc on August 06, 2007) | ||
| Muddog16 (Muddog16)
Registered Member Username: Muddog16 Post Number: 358 Registered: 11-2004 Posted From: 4.224.204.18 Rating: N/A |
Gus when I said load I meant RPM excuse the miswording! Sean if the oil was comtaminated before the rebuild and the oil coolers were not cleaned that stuff ended up right back in your engine! | ||
| Mark R. Obtinario (Cowlitzcoach)
Registered Member Username: Cowlitzcoach Post Number: 147 Registered: 4-2001 Posted From: 204.245.228.223 Rating: N/A |
You should have at least 10-15 degree drop in temperature between the inlet and outlet temperature if you are having adequate flow. If you have in excess of 30-35 degrees drop in temperature you are definitely having a flow problem. With that great of a drop in temperature you certainly should not be overheating. If you are having less than 10 degree drop in temperature you are having a cooling problem. Since you indicated it took longer to overheat when you had your hydronic system operating I would tend to think you have one of two problems. The first is inadequate flow and the second inadequate cooling capacity. Or a combination of both. The inadequate flow is a water pump problem. Since the pump is not that hard to access I would definitely swap it out to eliminate that problem. While it is out, I would also swap out the t'stats just to make sure they are not contributing to the problem. Or at least pop them out and test them to ascertain whether or not they are opening and closing properly. In regards to the inadequate cooling capacity,if you have viscous clutch fans I would defintely lock them to the shaft to determine if that is the problem. The clutches do fail over time and it isn't always visually apparent they are not working properly. If they are not working properly you will never have adequate cooling capacity if the ambient temperature is very high. Also, as you look at your fans and shrouds, make sure there are not any gaps around the radiators. It is a lot easier to suck air through gaps than it is to suck air through a radiator core. The other part of air flow is to make sure there is someplace for the air to escape once it has gone through the radiator. It doesn't do a lot of good to seal everything up to make sure all the air that the fans are pulling through the radiators if that air has no place to go. Good luck and keep us posted. Mark O. Castle Rock, WA | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 639 Registered: 1-2003 Posted From: 67.142.130.43 Rating: N/A |
OK, here's the result of pulling the grade today: Temperature got up to around 205 or so, but we were able to make it over the grade. I pulled over and managed to get back to the engine bay while the temp was still around 200. First off, the fans and radiators are doing *something*, because I could hardly stand behind them there was so much heat coming off them. Nevertheless, I was able to get some readings, and it appears I have a 10° drop from the inlet "Y" to the outlet "Y". Getting a reading from the individual radiators themselves wasn't possible -- I couldn't stand close enough for long enough. That 10° drop was pretty consistent as the whole shebang cooled off -- ~202° to ~192°, ~198° to ~188°, ending up at about 185° to 175°. According to Mark's post, above, 10° is marginal, and it sounds like I should be looking at the radiators as having inadequate heat rejection for some reason. I can move the fans with the engine off, so, per Gus, they are viscous couplings. I don't see any obvious way to "lock" these -- what should I be looking for? I now have a bigger problem -- loss of power and more smoke. When I stall-test, I can only get about 60% engine load, and I'm not seeing any turbo boost. My first guess on this is that it is starved for fuel, and I am noticing that the fuel level in the bowl on my Davco 380 is very low (lower than it has been, which shouldn't happen on a FuelPro -- it should only go up as the media becomes clogged). Anyone want to venture a guess on this problem? -Sean http://OurOdyssey.BlogSpot.com | ||
| Mark R. Obtinario (Cowlitzcoach)
Registered Member Username: Cowlitzcoach Post Number: 148 Registered: 4-2001 Posted From: 204.245.250.153 Rating: N/A |
We have welded the end of the shaft to the fan coupling. It makes it really hard to remove the fan coupling later but we found that more times than not, we needed more fan than less. And the cost of viscous fan couplings are pretty steep for the marginal increase in HP or decrease in fuel mileage you get when they are working. Since you have such a small amount of heat differential I am inclined to think you have more of a cooling capacity problem than flow problem. The fact you are less apt to overheat with your hydronic system working reinforces that idea. Turning on the hydronic system isn't much different than turning on the heater/defroster on high for a little added radiator volume (it can make it pretty hot inside the cab but it can make the difference between making it to the top without stopping or having to stop multiple times). Do you have any idea of what your fuel pressue is? You may have a lift pump that is getting weak. Or you could have something plugging up your fuel intake inside your tank restricting fuel flow. It isn't likely the return line is plugged because the fuel level in your filter is low. If you are not getting enough fuel volume it can contribute to overheating as well--engine having to work harder to acheive the same result. Since turbo boost is a direct result of exhaust, the greater the volume of the exhaust the greater the turbo boost will be. If you are not getting anything more than about 60% of your engine's power you aren't going to get much turbo boost. Is there any way you can get to the front side of your radiators--like through the side panel? If so, with your handy dandy IR thermometer you should be able to see which radiator is doing what. | ||
| James Stacy (Jimstacy)
Registered Member Username: Jimstacy Post Number: 88 Registered: 1-2001 Posted From: 75.41.0.216 Rating: N/A |
Sean, Knowing we are looking at unusual causes for heat problems: Trans clutch slipping can be tested without a wrench. Procedure is in Allison book. It's simple but dangerous. Don't depend on my memory, check the book. IIRC, vehicle is blocked at tires but park brake released, first gear is engaged and throttle applied. If clutch OK, it will bog down the engine, if not the engine will continue to gain RPM. In the 700 series the clutches used by first and reverse are also used by second and third. Both can be tested without moving the coach. BE VERY CAREFULL. Keep kids and dogs well away. Another unusual problem after rebuild: the fitting allowing fuel to exit the fuel rail in the head to the fuel return line, looks like a normal brass fitting (often an L), but it has a restriction orifice built in to keep fuel pressure up at the injectors. If it has been replaced by a standard fitting, pressure will be low. BTW this is one place where more restriction can improve power. A spring loaded check valve here, rather than a loose flap type of valve will raise the fuel pressure in the head. Of course, to make more power, you burn more fuel, which causes more heat...... BTW, the water pumps for the 6V92 and the 8V92 are interchangeable mechanically but have different flow rates. You always want the 8V92 part. The impellers can slip and reduce flow, drive you nuts. Welcome to the world of buses. Jim Stacy | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 765 Registered: 11-2004 Posted From: 72.91.168.128 Rating: N/A |
*****You should have at least 10-15 degree drop in temperature between the inlet and outlet temperature if you are having adequate flow. ****If you are having less than 10 degree drop in temperature you are having a cooling problem. ****Nevertheless, I was able to get some readings, and it appears I have a 10° drop from the inlet "Y" to the outlet ****According to Mark's post, above, 10° is marginal ****I now have a bigger problem -- loss of power and more smoke *****My first guess on this is that it is starved for fuel, and I am noticing that the fuel level in the bowl on my Davco 380 is very low (lower than it has been) ****Do you have any idea of what your fuel pressue is? You may have a lift pump that is getting weak. Or you could have something plugging up your fuel intake inside your tank restricting fuel flow. It isn't likely the return line is plugged because the fuel level in your filter is low. ****If you are not getting enough fuel volume it can contribute to overheating as well--engine having to work harder to acheive the same result. Since turbo boost is a direct result of exhaust, the greater the volume of the exhaust the greater the turbo boost will be. If you are not getting anything more than about 60% of your engine's power you aren't going to get much turbo boost I'm still betting amongst the myriad of problems that you have encountered - you have a fuel pressure problem, and Mark and you have made a pretty good argument in support -see above - HTH | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 766 Registered: 11-2004 Posted From: 72.91.168.128 Rating: N/A |
James - thanks for reminding me - Sean seems to be "in tune" with his power plant, has a tach (I believe) and any slip in the tranny would be evident to him - and I noticed you referenced fuel pressure too - FWIW | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 468 Registered: 7-2006 Posted From: 66.217.103.119 Rating: N/A |
Re: "I now have a bigger problem -- loss of power and more smoke. When I stall-test, I can only get about 60% engine load, and I'm not seeing any turbo boost. " If it's black smoke, it's either too much fuel, or too little air, right? Ok.... please excuse me if this sounds dumb, but I just gotta'' ask.... Does that engine have an emergency shut-down flapper, and if so, has it been insured that it is wide open, allowing for full air volume into the engine? I think it'd be safe to assume that a partially closed flapper would give you those symptoms, just as a collapsing air hose/duct from the filter to the engine......? It's possible to have two separate problems, totally unrelated.... | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 423 Registered: 11-2005 Posted From: 63.97.117.43 Rating: N/A |
Muddog, I wasn't responding to your post, guess I missed yours. I was responding to Sean when he said "I can't be looking while the coach is under load." The coolant circulation rate is independent of the engine combustion load except for temp increase due to this load. Same temp, same rate and press at given rpm. This high rate of circulation at hot temps will make the hose collapse. I forget for sure which one but as I remember it is the radiator inlet hose. Makes sense since there is press drop going from hot to cooler. | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 767 Registered: 11-2004 Posted From: 72.91.168.128 Rating: N/A |
John - It is entirely too simplified to call black smoke conditions under load to be caused by "over fueling" or "under aspirating" the mill - black smoke under load is more precisely and simply the lack of "complete" combustion of the fuel - this can be caused via a multitude of scenarios - normally I would agree with the fueling/breathing scenario had Sean not been down these roads before - there appears to be something more sinister about this scenario than the average problem encountered by other board members - maybe I'm wrong - FWIW | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 471 Registered: 7-2006 Posted From: 66.217.103.119 Rating: N/A |
Hope you're wrong, Niles! I tend to be a bit more optimistically minded, looking towards the simplistic, rather than complex... Sean's been down the "overheating" road, but he mentioned that the "low power/black smoke" is a new one... After what Sean has been through, I wish the hell it's just simple solutions, rather than a worse case scenario. | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 71 Registered: 1-2007 Posted From: 65.61.96.82 Rating: N/A |
Wow Sean, With all thats going on I sure would be looking for a shop with a chassis dyno so you can nail down whats happening under full load. I would want it as warm as possible when they put it on the dyno and run it as hard and long as the dyno can. By the way, did you ever use up the tank of fuel you had when all the trouble started? You have not had much luck lately, hope it improves soon! Don 4107 | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 640 Registered: 1-2003 Posted From: 67.142.130.17 Rating: N/A |
OK, a few answers: No, there is no emergency flapper. AFAIK, no DDEC engine was ever equipped with those, only the mechanicals (but I am open to being corrected on this). We did just go through the whole air induction system, so I am pretty sure it's not blocked. This latest issue -- low power, more smoke, came on fairly suddenly, just in today's driving. I don't think it is related to the heating on the grades, which I am now starting to believe is a partially obstructed radiator (or two). We're going to see what kind of smoke we get when we start it cold in the morning. The smoke we had today was not black -- I would call it gray. And we've seen similar symptoms before: after my first rebuild, we had a fuel delivery problem. Turned out to be a partially crimped main fuel supply hose. Since this developed fairly quickly, I am assuming something else is causing the fuel restriction, if that's even the problem. We took on another load of fuel today, and it's possible there was some crud in it that has plugged the secondary, so I might try changing that. Two other factors here are adding to the mystery: The first is the infamous Kysor fuel pressure switch. It was working OK when we drove in to PEDCO, but, as I related elsewhere on the board, I had cranking problems after the rebuild. Since the switch is NC and opens when the fuel pressure builds to 10psi, one possibility is there is nothing wrong with the switch, but that fuel pressure was simply building too quickly during cranking -- not sure if that's even possible, or what would cause it, but it may implicate the lift pump in some way. Of course, the lift pump came off and went back on during the in-frame. The other mystery is the Davco FuelPro 380. Normally, the fuel level in the clear bowl starts out at the very lowest level when a fresh cartridge is installed. The level steadily rises over time, until it reaches a line imprinted on the cartridge, which tells you to install a fresh cartridge. Inexplicably the fuel level is back down to its lowest point. Which tells me something there is amiss. Now the last load of fuel, around 100 gallons, that we put in in Arizona was low-sulfur (500ppm). (That, BTW, was the first fuel we put in since the infamous 260 gallons of cheap ULSD in Oregon.) Today in New Mexico we put in another 150 gallons, and this was, again ULSD. I have read an excerpt of a report from the Idaho National Lab, which indicates that one issue with ULSD is its higher solvency, which tends to dissolve years of crud out of fuel systems, which then promptly plugs the filters. This same report also indicated that the lubricity additives that are put into ULSD (to replace the lubricity lost during the process of removing the sulfur) have been shown to plug jet fuel-water separators, and the report goes on to speculate that diesel fuel-water separators may have a similar issue. Of course, the FuelPro 380 includes a water separator, so this also has me wondering. One thing I might try tomorrow is to find some fittings I can use to bypass the FuelPro altogether, to see if that cures the problem. The secondary filter, which will remain on the engine, will provide protection during the test. (I opted to keep my secondary, even though FuelPro proponents claim it can be eliminated.) That sort of begs the question: Is anyone else out there running a FuelPro AND using ULSD experiencing a problem, or am I on a goose chase here? -Sean http://OurOdyssey.BlogSpot.com | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 698 Registered: 10-2003 Posted From: 71.58.117.21 Rating: N/A |
Has the exhaust past the turbo been checked for restriction? | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 701 Registered: 10-2003 Posted From: 71.58.117.21 Rating: N/A |
I assume that it is intercooled, and that when they rebuilt the engine, they removed the intercooler and cleaned or replaced it? Have the fuel pressure, exhaust back pressure, air inlet restriction, and boost pressure been checked with a gauge? As you say it is a DDEC? Is there a way to check the engine timing if it is electronically controlled? | ||
| Jim Wilke (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 159 Registered: 2-2001 Posted From: 69.77.156.44 Rating: N/A |
"I now have a bigger problem -- loss of power and more smoke. When I stall-test, I can only get about 60% engine load, and I'm not seeing any turbo boost." If I understand what you are describing here: You put the bus in gear, brakes on and give it full throttle? Then read an output from the DDEC which says 60% power? If this is so, and you have not done this when the bus was running well, this may indicate a non problem. The torque converter "stalls" or becomes nearly a solid connection at an RPM way less than the max engine RPMs. If the engine (especially a 2 stroke of any kind) can't get to full rated RPMs, it can not make full power. Now, I may be interpreting this incorrectly because it may be that the DDEC is saying "only 60% of normal power AT THIS RPM setting". Also, don't give up on the possibility of fan clutches partially slipping. Ten degrees drop accross the rads wouldn't be that far off if your clutches slip too much at full power & RPMs. If you could pull 15-20% more air through the rad with the same coolant flow, there would be more drop. We just had the same problem with a truck that ran fine in NC but got progressively closer to overheated as we drove down to S. Florida with an increase of 10-15% in ambient air temps. On a hot engine, the air produced by the fan if the clutch is right should be a huge blast and you should clearly hear the fan from 20 feet away when revved. If the air flow seems weak and the fan doesn't really roar, I'd suspect the clutch. On an automobile, the life of the fan clutch in the South is less than 100,000 miles. Also, it MIGHT be that your clutches have a fill plug. If so they can be topped up with a special fluid. Chances are they won't though. If they are hydraulic clutch fans, they will have a thermostat, often a coiled spring in the center of the clutch facing the radiator which works a valve inside via a shaft & seal. Often these thermostats are filled with dirt due to the little seal leaking which would help to diagnose a failed clutch. Now, to mention the good side of a fan clutch. In cold weather a solid fan hookup may overcool your engine because thay have such massive cooling systems | ||
| Hans (Buellhans)
Registered Member Username: Buellhans Post Number: 68 Registered: 2-2007 Posted From: 199.60.181.9 Rating: N/A |
RE and RE pump STOP. You can rebuild it in place drop the water buy the new seal , impeller and do it in place . If it dont leak oil or leak coolant in do it in place . is your rads building presssure? 92s haave a thirteen pound cap somewere in the system check that . Then the stats . Then the rads . Its not a mystery coolant ,air , pump , check it out | ||
| Hans (Buellhans)
Registered Member Username: Buellhans Post Number: 69 Registered: 2-2007 Posted From: 199.60.181.9 Rating: N/A |
Are your rads plugged ? LOtsa rads get alot of debree in between the fins , Look in there with a flash light place inside or have someone shine it inside on the core and look from the out side if you can see the light . Did you fix the smoke problem? | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 641 Registered: 1-2003 Posted From: 67.142.130.45 Rating: N/A |
OK, I've had an "Aha!" moment... Reading through the pile of .PDF literature I downloaded from Davco back when I bought my unit (from a private individual on this board, or maybe the other one, who bought it and never used it), I found this trouble-shooting tip:
This is, of course, exactly my symptom, so I am hoping I've hit the solution as well. I did not think they opened up the unit at Pedco, but it's possible they had to to remove/reinstall it. I can see the spring, which looks fine. Tomorrow, I will remove the bowl and cartridge to check for a missing grommet. Fortunately, I carry a spare filter/grommet package with me. I have my fingers crossed that this is the whole low power problem. Yesterday, before my final stall test, I had topped up the bowl with fresh fuel. This morning, after starting up cold (where all looked normal), we drove around for only a few miles, and I did not notice any smoke or power problems. At this moment, the fuel level in the bowl is still above the bottom collar. That will still leave me with the heating problem, which I am now convinced is routine (whatever that means) degradation of the cooling system. I'm thinking, specifically, of silicate drop-out/gelation partially obstructing the radiators. Perhaps I will try to find someone who can run some caustic solution through the rads to clean this out. Alternatively, I can change to clean coolant with a lower percentage (~35%) of antifreeze and see if some of the silicate will just dissolve back into the coolant. Answering some other comments: Hans -- the original smoke problem was blow-by from a dirt-worn engine. I had the whole engine in-framed (eight new kits and rebuilt heads). Read the blog for details. Re: radiator caps -- I don't have any. There is a non-relieving hinge-and-bail style filler door on the recovery tank, and a separate pressure relief valve, with a pushbutton on it to manually relieve the pressure in order to open the filler. I don't know if the relief is working properly (vis-a-vis proper pressure setting) -- removing it to test is a real struggle. But it's not opening, and I would not expect it to until the coolant was up over at least 230°, so I don't think this is part of the problem. Regarding exhaust restriction: I can't see any, and it was not giving symptoms of restriction for the first three days after the in-frame. Yes, the aftercooler was removed, cleaned, inspected, and replaced. (BTW, all 8V92-TA's are aftercooled.) The radiators are not plugged (on the air side). I just had them cleaned, and I inspected them several times during this situation. Lastly, I still haven't figured out any way to lock the fan clutches. Also, my efforts today to find an optical tach here in Santa Fe came up empty (mostly I got blank stares, or pointed to the whizz-bang, penis-compensation tachometers that obstruct the driver's vision in low riders and hot rods). Nobody knew what I was talking about when I asked for a manual fluid pressure gauge, either. -Sean http://OurOdyssey.BlogSpot.com | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 472 Registered: 7-2006 Posted From: 66.217.102.209 Rating: N/A |
Re: "Lastly, I still haven't figured out any way to lock the fan clutches. Also, my efforts today to find an optical tach " I'm not too sure the tach will serve any benefit, since fan clutches are (usually) dependent on ambient temperature, as well as rpm. If the rad flush doesn't do it, I'd change out the fan clutches and be done with it. They don't last forever... There should be a way to lock 'em up, though. Most automotive types have a spring on the engine side that can be moved to a "locking" position. The comments regarding the water pump and impeller failure/slippage makes a world of sense also. I think I'd change the pump just for argument's sake. For all you've been through....? Well...... at least all this is keeping you busy and out of the bars.... (HAR) Lotsa' luck, eh? | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 642 Registered: 1-2003 Posted From: 67.142.130.24 Rating: N/A |
Update: Well, I'm certain I found the low power problem. I'm not sure how the fuel fell below the level of the grommet in the Davco, because the spring is in place and intact, and there was, indeed, a grommet between the filter media and the housing. That being said, now that I've looked the thing over, and read every little bit of documentation I could find on Davco's web site, it is very clear to me that, once the fuel level fell below that point, the lift pump would have had a real struggle to supply any fuel to the engine at all. So, as I speculated early on just from "feel", it was a fuel starvation problem. The cartridge and grommet that I just removed have been in there quite a while -- I'm going to say well over a year and 20-30,000 miles. While the visual indication was that the media was only half used, the grommet felt spongy. Possibly this is just due to age, or possibly, as this was an older filter/grommet set (with a Detroit part number), the grommet material was incompatible with the new ULSD fuel. Or maybe it was BUNA-N, which has a known problem with shrinkage under ULSD immersion, as the aromatics which swelled it in the first place are lost. In any case, I elected to change out the media, grommet, and O-rings, and filled the bowl with fresh fuel. I haven't done a test-drive yet, but I am confident that this takes care of the low power complaint I voiced here on Monday. The other possibility is that the spring, which is probably ten years old and has been compressed the whole time, is weak. So I will be picking up a replacement for that as well, whenever I pass another Davco dealer. Returning to the cooling issue: I have received information in this same thread on the other board from another Neoplan owner that the fan clutches have no lock-up mechanism, nor do they appear to have any kind of fluid fill port. So I think the easiest strategy to confirm proper fan operation will be to find an optical tachometer and shoot both the blades and the pulleys to make sure the clutches are engaged. Can anyone point me at a brick-and-mortar store that carries these? As for the water pump rebuild, I will definitely do that, but I will have to have a shop handle it -- I have no way to deal with draining the several gallons of coolant it will take to get to the pump. Also, I want to have a complete coolant change at the same time, to about a 35% mix of extended-life coolant, and a shop is equipped to deal with the proper disposal of the old coolant. In this vein, can anyone recommend a shop here in Santa Fe? If not, my next large-ish cities will be Wichita, KS; Joplin, MO; and Springfield, MO. Thanks, everyone, for all the help. -Sean http://OurOdyssey.BlogSpot.com | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 768 Registered: 11-2004 Posted From: 72.91.168.128 Rating: N/A |
Sean - I'm not so sure that, if this works, the 'leaning' of the fuel might not have contributed to the heat problem -FWIW | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 702 Registered: 10-2003 Posted From: 71.58.117.21 Rating: N/A |
Starving for fuel won't cause a diesel to overheat unless the computer retards the timing, if it can do this. On diesels; more fuel- more heat, less fuel or starvation- less heat. I don't know why you even fool with that Davco or any other of those fancy filters, as the two that they use in the coaches have served hundreds of coaches over millions of miles without problems. I've experienced similar problems with those add on's on car diesels after time. Of course, to each his own. BTW, a good fuel pressure gage setup would be useful to monitor this when going down the road. | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 703 Registered: 10-2003 Posted From: 71.58.117.21 Rating: N/A |
Oh, another thought....is the torque converter locking up like it is supposed to? | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 769 Registered: 11-2004 Posted From: 72.91.168.128 Rating: N/A |
Absolutely John - But earlier in Sean's nightmare I advanced a SWAG that he had a fuel supply problem and a SWAT that due to that problem the unit injectors weren't vaporizing the fuel, which what I was refering to above - to create heat it would have to be both lean and not vaporized - Still just a WAG | ||
| Hans (Buellhans)
Registered Member Username: Buellhans Post Number: 70 Registered: 2-2007 Posted From: 199.60.181.9 Rating: N/A |
So okay you figure there is no pressure cap ? so tell me how does your cooling system relive it self of pressure ? Im not trying to be abrasive just trying to help your situation out . So the cap looks like a little round plug somewere on your coolant tank behind on top some were inspect closely | ||
| James Stacy (Jimstacy)
Registered Member Username: Jimstacy Post Number: 90 Registered: 1-2001 Posted From: 75.41.6.95 Rating: N/A |
Pressure cap raises boiling point of coolant (approx 3 degrees per pound of pressure), but does not improve cooling significantly. AFAIK pressure (or lack of) might effect boiling but not cooling. | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 645 Registered: 1-2003 Posted From: 67.142.130.43 Rating: N/A |
Hans -- please read that entire paragraph. There is no "pressure cap" such as you would find on an automotive radiator. There is a filler door, which latches with a bail bar and has no way to relieve pressure. And then there is a separate pressure-relief valve, on about a 1/8" line coming out of the recovery tank. The relief valve also has a pushbutton to operate it manually. And, as I also wrote, the relief valve is not opening, nor would I expect it to until the coolant temperature reaches at least 230°. So I don't think that's the problem. -Sean http://OurOdyssey.BlogSpot.com | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 69 Registered: 3-2007 Posted From: 76.4.136.26 Rating: N/A |
hey sean.I hate to bring this up,but have you thought about getting another coach and get a different headache? LOL I have talked to a bunch of DD here in Ocala Fl and I have no answer for you at this time either. | ||
| Hans (Buellhans)
Registered Member Username: Buellhans Post Number: 74 Registered: 2-2007 Posted From: 199.60.189.9 Rating: N/A |
Yes I do agree and I was not saying there was a pressure cap on your bus that looked like a normal rad cap . ITs a bus not a car . Your cooling system needs pressure and it also needs to relase excess pressure . It must as you say have a proper seal on The bail flap thing me . Im with Marvin maybe you should part it out | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 711 Registered: 10-2003 Posted From: 71.58.117.21 Rating: N/A |
1.Did that coach have an 8-92 in it origonally? 2. If not, were the radiators upgraded? 3. When you said you had the radiators cleaned- were thed rodded out or just pressure cleaned through the fins. And..... what was the outside temp when you were climbing those hills? Over 110 degrees or what? | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 648 Registered: 1-2003 Posted From: 67.142.130.20 Rating: N/A |
1. No. 2. Don't know for sure. 3. Cleaned only on the outside. (4) 105°. 1 and 2 are not really relevant to the discussion. I'm not talking about some sort of absolute performance issue related to an ideal bus,but rather about performance issues with the bus today vs. some point in the past (when it had exactly the same engine and radiators it has now). Same goes for #4 -- I've pulled 6% grades in 105° heat without this level of problem. (Since you've asked, though, and for the curious -- this coach was built in Germany, probably with a Mercedes or Deutz that was intended, from day of order, to be thrown away. It was repowered in the US, when it was still an empty shell, at the Neoplan factory, with the exact powertrain that was being used in US-built coaches at the time. It is impossible to know how much of the cooling system was changed out as part of the repower. Probably all of it, because the original engine was likely only 160bhp, and may even have been air-cooled, as were the Deutz's.) As for #3 -- it will be well north of $2,000 to have the radiators removed, opened, and cleaned if necessary. I want to be certain that's the problem before I spend that kind of money. I'd like to clarify that I am troubleshooting a problem -- not investigating an engineering design. I am not looking to change the design of my power train, including the cooling system. It worked fine before -- I just want to fix the problem. I do know that there are more efficient engines, transmissions, radiators and fan clutches, any of which could be brought to bear if we wanted to change the basic design. But I've been around the block a few times, and I'm pretty familiar with my powerplant. I have 75,000 miles of experience with this powertrain in this coach. Which is why I asked the specific questions that I did when I started this thread. And, don't get me wrong, I am grateful to everyone who has responded and for the troubleshooting suggestions that are beyond the purview of those questions. So, please keep the suggestions coming, because I'm not to the bottom of this yet. But please also keep them in the vein of troubleshooting, not re-engineering -- it's really more than I can handle to contemplate changing any part of this design. -Sean http://OurOdyssey.BlogSpot.com [Edited to remove unwarranted crankiness.] (Message edited by sean on August 11, 2007) | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 475 Registered: 7-2006 Posted From: 68.205.165.5 Rating: N/A |
Sean - Re: "I am not interested in changing the design of my power train, including the cooling system. It worked fine before -- I just want to fix the problem. I've heard suggestions now to replace all four of these. Not because we think that's the part that failed, but because "it would work better only if...". I have yet to get even a single answer to three of those five questions. " After re-reading your initial request, and re-reading each subsequent post, it sure appears to me that each of your questions were answered in great depth! I doubt anyone feels that an arbitrary replacement of parts is the right way to resolve a tough problem, and certainly no-one had suggested that (in my opinion, anyway).... However..... After an engine rebuild, it'd always had been fairly customary to flush the radiator, replace the thermostat, and replace belts, etc... Why would anyone want to jeopardize a high dollar rebuild, by ignoring simple maintenance assignments? Radiators will build up with sludge through usage. These buses have had enough previous use, to demand a decent flush. Especially so, since the engine suffered enough major problems to warrant a rebuild. Thermostats can corrode and stick open, closed, or half-way between... Fan clutches weaken through use, and eventually must be replaced. How do we know when? When problems begin to rear their ugly heads, usually, and it sure sounds like that's what you're experiencing. Intermittent overheating can be caused by many things, but the process of elimination is about the only way to isolate the cause. It needn't be costly, but it's going to be time intensive. We can speculate and ponder, and we can guess away, but no-one here behind a monitor is getting their hands as dirty as you. You asked for suggestions, Sean.... I wouldn't discount a single one! Instead, I'd take each one, and prioritize them, according to ease of duty, and cost. I wish you luck! | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 651 Registered: 1-2003 Posted From: 67.142.130.20 Rating: N/A |
After re-reading your initial request, and re-reading each subsequent post, it sure appears to me that each of your questions were answered in great depth! Well, I've just done the same thing. So perhaps that was a bit overstated. Let's say that some of the questions have not been answered completely, as I had envisioned (not a complaint -- it is, after all, free advice). For example, I would still like to know what the steps are to remove and replace the water pump (and mine, BTW is the "walking" type). By which I mean something like "remove bolts a, b, and c, then the circlip, make sure you have gasket 123DEF on hand" etc. And I would also still like to know if there is any non-intrusive way to determine if the water pump is even a suspect in this caper. And really, I probably shouldn't post when I have my hackles up. But the preceding post really bothered me, because the implication of those questions is that the problem is the loose nut behind the wheel. After 75,000 miles, I know how my coach drives, and I know when something changes from its "normal" behavior -- I came here looking for help troubleshooting a specific problem, not advice on how to redesign the system, nor a lecture on how to drive (and I've gotten both). Yes, I asked for suggestions, and I am grateful for all of them, because you are right, it is up to me then to prioritize them and do what makes sense. And most everyone here has been very helpful, and kind, and forgiving of my ignorance on certain subjects. I am miles ahead for having all of this advice in front of me. So I ask forgiveness for the late-night cranky response to questions that were, in my mind, well outside the scope of the discussion. -Sean http://OurOdyssey.BlogSpot.com | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 1965 Registered: 1-2001 Posted From: 75.108.76.56 Rating: N/A |
Sean, like many others I suspect, I was not really aware until your post yesterday that this all came on very suddenly and that everything had worked properly before. I probably should have assumed that, but you know what happens when you assume something. LOL Although others feel otherwise, I still firmly believe you have a collapsed input hose, a clogged check valve or a clogged input strainer in the fuel tank, or a combination of these. I also feel that the lack of fuel could cause the overheating problem since you are not really generating enough HP to get over the passes without overloading the engine. Just like the engine will overheat when you do not down shift properly when climbing grades. Just my opinions, for what they are worth, and good luck on finding the problem(s). Richard P.S Fix the fuel problem first, then worry about the overheating problem. It is certainly going to be very interesting, to many people, to find out what the problems really are. (Message edited by DrivingMissLazy on August 11, 2007) | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 477 Registered: 7-2006 Posted From: 66.217.105.182 Rating: N/A |
Sean - I wasn't soliciting an apology; none is/was needed! When I read answers to questions, I see the ones responding becoming as frustrated as the ones asking... It's damned tough to diagnose (or fix) something that you can't see, feel, or hear. But there isn't one of us out here, that wouldn't love to be able to provide an answer that may resolve a problem.... I think it'd be safe to say, that -we all- share in your frustration. It's human nature to suggest eliminating the simplest things first, like poor driving habits, etc., so I wouldn't become too bothered by a comment suggesting I may be the cause of my vehicle's problem. Regarding the water pump impeller..(?) Those things can become loose on their shaft, and there's no easy "test" that will indicate it has. If it slips, and doesn't pump enough coolant, it'd be most likely to occur during higher engine rpm, or when/if a restriction presents itself within the cooling system. Since there's 3rd party plumbing associated to and from the OE system, it complicates things quite a bit. If there are valves to eliminate the "house" loop, I'd temporarily turn 'em off, and try to get back to the basic OE system first. If the problem persists, I'd then have the radiators flushed to insure there's no obstructions. Next, would be a water pump replacement, then fan clutches. Matters like "poor engine timing", or lean fuel, can cause excessive heating, but you'd also experience other problems long before the overheating occurs. You didn't mention -always- losing power prior to the overheat condition... Or poor starting, rough idle, etc., so in my personal opinion, I'd consider any timing/fuel problems to be a separate issue, and concentrate on a cooling system problem that you've said you've had prior to the rebuild. It's a beautiful conversion, Sean. It may not be a picnic now, but I doubt you'll ever regret the time and effort you're spending on it.. I think I can speak for all of us out here, when I say I wish I could be of more help to you. Cheers! | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 478 Registered: 7-2006 Posted From: 66.217.105.182 Rating: N/A |
Stop posting while I'm typing, Richard! HAR!! (Message edited by john_mc9 on August 11, 2007) | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1111 Registered: 5-2001 Posted From: 65.74.67.130 Rating: N/A |
Sean, I don't see that anyone has suggested having your coolant analyzed to see if anything shows up. I seem to remember that that is a service that is available. The reason that I thought of this was because the impeller coming loose on it's shaft was mentioned. I thought that metal filings from that ought to show up in the coolant if this happens. I don't know what you might find out by doing this; I am only mentioning it as something that might be informative without costing very much. When a water pump bearing failed on a Cat engine of ours, it was plenty noisy. I would think that you would hear a loose impeller if it was pumping any water at all. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 654 Registered: 1-2003 Posted From: 67.142.130.38 Rating: N/A |
Tom, That's a great idea. I have the whole cooling problem on hold right now until I resolve the fuel delivery issue, though. -Sean http://OurOdyssey.BlogSpot.com | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 659 Registered: 1-2003 Posted From: 67.142.130.43 Rating: N/A |
Well, it turned out to be a restriction in the fuel return line, causing low power and poor injector cooling. More details in another thread, here: http://www.busnut.com/bbs/messages/11/18539.html?1187234129#POST118587 -Sean http://OurOdyssey.BlogSpot.com |
