| Author | Message | ||
| james dean boggs (Jd_boggs)
Rating: N/A |
I have heating problems on my 6v92 w/730 tranny. Had the radiator pulled disassembled and cleaned (rodded). Flushed the engine block at least 4 times with water. Still heating 200+ at 65 mph in 95-110 degrees in the desert of southern California. I think the clutch fan is faulty. I tested it this way: pumped air into the clutch inlet hose at 120 psi. At this time I could spin it freely with my hand. Then removed the air hose and with some resistance I could still turn the fan but NOT spin it. I could feel some drag from the clutch. The replacemt of this clutch seem too dificult for me because it has a bank of springs. And I don't know how to reassemble it. Easiest way out is to install electric fans but will I have enough air circulating at 2950 to 3300 CFM fans? I can mount 4 fans in the space of 33 inches by 36 inches. Will it be enough? PS The thermostat valves are working fine as is the shutterstat valve. PSPS How much air preasure does the "wet" tank require? This is NOT covered in my bus maintenance manual. The "wet" tank supplies air directly to the fan clutch by way of the shutterstat. | ||
| TWODOGS (Twodogs)
Rating: N/A |
have you done a compression test... | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Oh god, here we go again. Down dog!!! | ||
| Jim Ashworth (Jimnh)
Rating: N/A |
Fix what you have. It worked before and will work again. DO NOT reinvent the wheel!! IT WON"T WORK. Get the cooling system back to original condition and it will go another million miles. Jim | ||
| Matt Rating: N/A |
How about it two dogs, tell him what your test results where. | ||
| james dean boggs (Jd_boggs)
Rating: N/A |
Thank you for you kind words. Maybe I should explain further.... I've had this bus for a year and have spent the entire time converting. I'm at a point where I can start testing some of the systems one of which is cooling. This is a city bus not a highway coach. City buses are not designed to travel at 65+ MPH. Therefore one cannot assume that the cooling system installed in my city bus was desingned with enough capacity to cool everything properly at 65 MPH. I can travel at 45 MPH all day long and stay at 185-195 degrees. I searched the archives of this forum and others before requesting help here but didn't find answers to a few fundamental quesions. I am not one to reinvent the wheel but I have no evidence that this bus has proper cooling capacity because I have not studied diesel systems before. All this is new to me. The reson I'm asking these simple questions is to avoid reinvention. So if my simple questions annoy you just ignore me and move on. But if you have credible knowledge and constructive input. Please write me note. Thank You | ||
| Mike (Busone)
Rating: N/A |
Since I have been offline for over two weeks now I must have missed something. What happened to Two Dogs fan test? I hope your bus is ok TD. | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
First, I presume that your radiator is on the side of your rig. Second, I presume that your radiator intake is flush with the side of your rig. If these are both true, there is your problem. I'm going to get mud slung at me here but you'll really need a wind tunnel to re-invent this thing... First you need to break up the air running down the length of the bus (engineers call it laminar-air-flow). Air at speed will have a natural tendancy to "skip" over the opening for your radiator (like hitting a small pot-hole at 70 MPH with a bus, as opposed to 10 MPH with a skateboard). If you make the side of your bus break up the air (create turbulence) two things will happen: 1) You'll make it easier for air to change direction... 2) You'll increase your drag (wind noise is proportional to this effect...) I belive Dave Galey had a little suggestion in his "Bus Converter's Bible" to weld a piece of "L" channel to the side of your bus ahead of the radiator opening (how far ahead to place it and what size to use is where the wind tunnel comes in handy). The next thing you have to do is "convice" the air to enter your radiator. This is complicated also without a wind tunnel... Your best bet is to fashion a scoop for the air, or align several increasing-height louvers vertically to grab the air (turbulent or not) and cram it down the throat of your radiator. In all honesty the fan isn't going to do much of the work, no matter what rig you drive, when you get up to those speeds. It sounds like you have found your problem with your existing system... my advice: "fix it". I spent ~$550+ creating a replacement electic fan specifically for my setup (this exludes the $300-400 additional worth of telemetry for gauges and data-logging I put in at the same time and the $1800 secondary power-generation system that makes it all work!) The best advice you can squeeze out of these other guys will be about what I suspect is your original problem: Why the engine is getting so hot in the first place. You mentioned that you are running a 730? If I remember right (everyone will tell me I'm wrong if I am...) the 730s are 3-speed. What final drive ratio are you running? What is your engine RPM at 65MPH? If you run an old 92 in the upper revs too long it'll overheat anyway. These are important in figuring out what your problem is... Don' be skerd about electric fans... Just make sure you need to go that way. Cheers! Tim P.S. Almost forgot... the ol' 92 series generates a lot of heat in the engine compartment (2-cycles do this real good). Try putting a vent at the top of the engine door (on a transit like mine, it would be on the rear face of the bus) with a fan to force air out when it's hot. -T | ||
| Brian (Bigbusguy)
Rating: N/A |
I dont know what size electric fans you will need but they will need to be big. The Eagle I saw at the rally in OR has 2 electric fans I dont know the size but the motors look as big as starter motors .The owner said the fan blades was off the A/C condenser or evaporator. So It will work but you will have to build it your self. Hard to understand wat you are saying . But if you add air to the chutch it should lock up and you should not be able to get it to slip by hand. Sounds like somthing is blocked up or the valve that works it is not working. You could put in a electric soloniod and make it so you can turn it on manuly. Your wet tank should have the same psi as the others but I dont think is should the wet tank should feed any thing but the other tanks.I would not pull any air for any thing out of the wet tank or your valves well get all gooed up. Brian 4905 Kanasas City (home base Klamath Falls Oregon) | ||
| paranoidoftheoceanguy Rating: N/A |
If it will run all day long at 45...sounds like it's a gearing problem...a taller rear-end...3.73 or 3.50.....as long as you are on the flat you won;t have any trouble....would not take it close to a mountain tho.... | ||
| Marc Bourget Rating: N/A |
Tim, No mud slinging here, but I invite your further comments to the following points which I believe are true. I just believe they're true, but that's only an opinion based on my present knowledge and not a life or death thing with me. Air at the speeds the bus travels acts as an imcompressible liquid. I believe it doesn't need to be "tricked" into passing thru the radiator. It simply responds to the pressure differential created by a properly working fan. A city bus, travelling at lower speeds will require a larger capacity radiator and/or fan system compared to a OTR bus. [Some?] RTSs came with a longitudinal flap [running lengthwise] to stop circular flow of [heated] air while stopped/slow. Because the individual molecules of air are so small and of such light mass, they don't have the inertia to "Skip" over the opening. Just spoke with a MCI owner at Bus'nUSA. His radiator fan is strong enough that you really have to pull a piece of paper off the radiator grille. This was an improvement from before where the paper would barely stay ni place. Dave Gregory of So Oregon Diesel recommends removing radiator shutterstats. What injectors is Mr. Boggs running - i.e., what horsepower stock 277? or 350? etc Mr. Boggs flushed the system, but did he service the cooling system with a cleaner? | ||
| Bill Gerrie
Rating: N/A |
James You say you are running a Transit. I have a GMC5303 and when I had overheating problems I tried everything to lower the temp. No luck till a guy on here mentioned about the air intake. I removed the grill over the air intake and made a new one with larger louvers to allow more air and made sure the air passages were clean. I have the equivalent of a 7" dia pipe feeding air to the engine and no overheating since. You also mentioned the fan can be turned by hand with no air applied to the fan clutch. You should NOT be able to move it with no air. I have a commercially rebuilt fan drive for a 6V92 if you want for $100 US plus shipping. It is heavy so I hope you don't live far. Let me know. Bill | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Shoulda said "re-direct" not "convince". Woulda made more sense... alas my 15 minute edit time is long past... As for your pressure differential concept, yes air flow will be affected by a negative pressure on the face of a radiator (induced by the fan on the back), but that effect is less powerfull when the air must make an abrupt change in direction (even more so, when the air must pass through a perforated non-aerodynamic grille). If your radiator is on the side of your bus, having a mostly smooth surface for air to go over and then trying to re-align the air 90 degrees requires a heck of a lot of power. Using the example of a wing, air over the top is more turbulent, and slower, creating a pull in the direction of the lower pressure. By fouling-up the surface of the side of the bus you can create turbulence before the radiator opening, which should (wind tunnel test dictates results) make the power required to draw air in that flat surface easier. Now keeping in line with this wing concept, by placing static wing-like flaps that "curve" the air towards the radiator (high-pressure on the face forcing the air into the radiator, low-pressure setting up a "contour following turbulence" into the next flap.. repeat, etc.) will further reduce the power demand on the fan's drivetrain when the bus is moved at speed. This effect is even more improved if the flaps stick out progressively more the further back on the bus you go, so that it really grabs that air. From what I've seen, most manufacturers have the presence of mind to make their radiator grilles like this (even if the flaps are as small as 1" wide) save for my Gillig. Properly functioning radiator/fan combos should EASILY pull a piece of paper against the face of the rad. when operating at full-tilt. Shutterstats... well, the only reason I can see for Mr Gregory advocating their removal, is a long-lived hatred for their ease of malfunction, which ends up starving the radiator of fresh - cool air. And yes, I don't like the mechanical thermostats on those either (that's why mine are moved by a stepper, with an error detection/alarm built in). Of course this all assumes that Mr. B didn't put a "rock stopper" at his rear bumper, which would really mess up the undercarridge air flow and trap all that hot air in the engine compartment... I wouldn't have suspected you to throw mud Marc, having conversed with you in the past, it's just that everyone else... well... Cheers! Tim | ||
| Marc Bourget Rating: N/A |
Tim, Thanks for the non-mud-slinging compliment! I'm thinking someone gave you bad information on aerodynamics. Wing lift is greatly improved by laminar flow over the top (actually required if it is a laminar series airfoil) but all wings rely upon and benefit from relatively smooth airflow over the top. (This is why they de-ice wings before take-off on snowy/icy conditions). The lift generated is explained by application of the Bernoulli effect among others, Bernoulli was the topic of a thread on this BB long ago and you may want to look it up. Listen to Clarke Echols on the correct pronounciation of Bernoulli, btw. Turbulent air over the top of a wing is evidence of airflow separation, aka "a stall" which means little or no lift. While you can get some high co-efficient of lift values, at the expense of huge increases in drag, none of this is [very much] applicable to busses. Yes, intake grills provide resistance, but you overlooked the point that the mass of single air molecules is low and therefore they'll change directions relatively easy. I agree with your observation about the behind the wheels vs back bumper flap position. I think the first thing you must resolve is why a cooling system, designed at great expense, tested to extreme conditions and worked great for many years in regular service, now does't cool adequately. The first things to check are the changes from Stock and the slipping fan clutch is a big issue IMHO. Injector size would be the next. We can go further from there. Onward and Upward | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
As in just about all previous threads Marc, I have spared most people the exact engineering terms and science to explain a complicated set of concepts in a fairly short post. Yes, the mass of a single molecule of air is low. And depending on the altitude (subsitute barometric pressure here if your a real science "go-get'er"), the air is thinner up high, and denser closer to sea level. In fact, speaking of sea, the moisture content of the air and temperature of the air also have a great deal with the way air behaves in a pressurized flow over a surface (cold humid air has more resistance than dry hot air). And, given the right cicumstances, will create icing on colder lower pressure surfaces (ie, the upper 30% of the leading edge of a wing, causing a resultant build-up of frozen water crystals in a thick sheet-like mass - which progressively grows in a rear-ward direction to the flow of air. Ultimately this causes an out-of-design payload on the wings, and turbulence over the top of the wing surface do to the new inefficient shape of curve the ice made which - yes, will stall a wing and the attached aircraft sending it into whatever geographic landmark happens to exist at the end of its speed-momentum arc.) And all this STILL leaves out the angle of the airfoil relative to the direction of air flow over it's surface or the speed of the air flow, which could just as easily produce the lift-robbing turbulence. A significant point to make on the tail of that statement is that Laminar airflow requires a certain speed for it to occurr, AND its existance is inevitable when that threshold is reached for a given aerodynamic design. I prefer to keep the old dead people and the complicated math out of it, and give approximate information, which people can "discover the science" to. Mostly, I hope to point someone in the right direction, so that if they want the science (like in this post), they can ask for it and I wouldn't be wasting my time explaning it to them... And no, I didn't over-look the molecular mass of whichever of the roughly ten separate molecules that make up Dry Air that you were referring to (Oxygen, Nitrogen, Carbon Dioxide, Hydrogen, Argon, Neon, Helium, Krypton, Xenon - for a total approximate molecular mass of 29), the point I was trying to make was: While one molecule can have its direction changed easily, configuring your grille so that this may happen several trillion (+/- a trillion or two) times per mile will make your cooling system more effective. But... This all gets really far away from the point I was originally trying to make: He knows his fan has a bad clutch, he's isolated the problem down to a small number of parts it could be (less than five I think), he should just repair it and be done with it. I was mearly doing what he asked by submitting further suggestions that may help his situation in the event he was unable to resolve the fan clutch issue, and trying to disuade him from going through the expense, experimentation, and engineering which would be required to replace an existing belt system with a different electromotive system altogether (you hear that TD?) (Don't get me started on the mass-centroid-axis parameter of a good generator isolation system design... I've already offered to collaborate with you and produce an Excel based estimator for those who don't want the science of it... After what happened to me at the bank today I'm liable to ram my head repetatively into the wall until this headache subsides into unconsciousness ;) Oh and Marc don't read into my post that I'm upset, I'm just going "Damn, there goes another attempt to keep it simple..."  As always, have another round! Cheers! Tim | ||
| Sammy
Rating: N/A |
I would check the coolant "flow" of the water pump.Could have a bad pump, impeller slipping on shaft under a load.Easy to fab a simple test device. Check your trans cooler too. | ||
| Marc Bourget Rating: N/A |
Tim I, once again, agree with you - up to the point where we diverge (at different points) in the thread of knowledge, and about how to keep it "simple" It's a judgment call depending on the subject and who you're speaking to. I tend to feel that most anybody who watches or participates on the BBs (with minor exceptions) are both smart and knowledgable enough to pick up on fairly complicated things if we can "prompt" them out of their mental "couch potato" mode. I try to motivate by "tickling" them with info, but some object regardless - others even more "just because". Spoke with many converters at Bus'nUSA this weekend. Several commented about me being "too intellectual" Both curious and challenged, when I asked them a few questions and drew them out about the subject in question, they realized that they had the necessary info all along, it was just buried - a little bit!. Experiences like this somewhat justify my approach because we all "know" more than we think, if we can shake loose the memories! Another justification for my "mantra" Onward and Upward. | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Touche... Cheers! (<--My mantra...) Tim | ||
| Tom Caffrey (Pvcces)
Rating: N/A |
How about a wind speed sensor mounted in the engine compartment? Could that be a substitute for a wind tunnel? If a fan clutch that is designed to deliver 20 to 40 hp continues slipping, would it generate enough heat to damage parts other than the wear parts? Sailing vessels get most of their motive power from from the inertia of the slow moving mass of air that changes direction when it meets the sail. Some of those four masters would easily overtake their 10 knot tows leaving Puget Sound. I've seen a report of 14 knots. Just my two cents. Tom Caffrey PD4106-2576 Suncatcher | ||
| james dean boggs (Jd_boggs)
Rating: N/A |
WOW! I'm getting an education! And thank you for sharing your knowledge with me and others. I spent most of my adult life working in electronics is Silicon Valley. So, all this is new to me and it's soaking in slowly. Give me a little time. I'll get it done. 1. Don't know what size injectors it has but will find out. 2. Yes, the engine is side mounted and has a grill on both sides. 3. The bus is 40ft long and very flat walls. No obstructions nor fins like the sides of the 1970's MCI. Just flat as can be. So the only turbulance would come from the side mirrors. But they are mounted high. 4. There are no mud flaps at the rear of the bus. 5. There is a very worn mud flap just ahead of the engine and radiator which needs to be replaced. I think I can simulate or approximate the wind tunnel by placing "smoke" nozzels along the side of the vehicle and see if smoke follows the path to the radiator. I saw this in a black and white film in my high school physics class. Again, thank you for sharing your knowledge base. | ||
| Darnedcomputersnafuguy Rating: N/A |
James - What year, make and model bus do you have? You've never mentioned that, other than it's a transit with a 6V92TA & V-730 powertrain. Could be that somebody here may have a similar model and has come across the same challenges. | ||
| james dean boggs (Jd_boggs)
Rating: N/A |
Darnedcomputersnafuguy, I have an 1981 Flex/Grumman, 40ft powered w/ 6v92 and 730 transmission. Not too many of these around. | ||
| RJL Rating: N/A |
Ah, a Metro/870!! Trained over 75 transit drivers how to handle those things! We had a fleet of them: 12 81's like yours, 12 '84s and 20 '90 models. The '81s and '84s had the same powertrain you have, but the '90s had RH 6V92TACs/Voiths in them. Good bus, albeit a bit quirky. Example: Who's bright idea was it to literally "hang" the driver's platform from the ceiling, anyway? Or attach the rear suspension to the back of the fuel tank? (OTOH, it made for a smooth ride!) Is yours an ex-Santa Clara County VTA coach? You mentioned Silicon Valley, home of VTA, who ran about a hundred of the Metros (along with RTSs). (You still in the Silicon Valley area?) Anyway, here in Fresno, we ran the wheels off our Flxibles, w/o any major overheating problems even in our 100+° summer days. The most common mechanical reason one would go down from overheating was if there was a problem with the fan clutch - which sounds exactly like the problem you're having. I do need to clarify, however, that this was a rare failure, and that these coaches were also on a strict PM program, which included the cooling system. (Radiator pressure-washed every 10,000 miles, IIRC.) SO, my suggestion is that you mosey over to your local transit agency's main shop. Ask to speak to the shop foreman, and when you meet him, inquire if they ever ran Flxible Metros. If so, tell him you've got one with a cantankerous fan clutch, and was wondering if any of his shop guys might like to make a few extra bucks after hours helping you fix it. I know we had guys who would moonlight. . . Fix the mudflap, too. HTH, RJ PD4106-2784 Fresno CA | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
Several years ago, Gene Rochester (a bus nut of course) ran a rather unscientific experiment on his Eagle to answer these questions. He taped a series of short ribbons along the side of the bus and along the radiator door. Lo and behold he discovered that the radiator was actually in a low pressure area and at highway speed the ribbons were standing out from the radiator area. It would seem to me that a deflector in front of (before) the radiator would be required to break up the wind, but I will defer to the experts on where to place a spoiler. Go for it Marc. Richard | ||
| Stan Rating: N/A |
Good point Richard. An emperical test and 'cut and fit' solution (your post on using misters) shoots down a lot of theory. After we have chopped, cut, modified and changed a bus from its original configuration, every one is unique. What works on one, may not work on another. | ||
| Marc Bourget Rating: N/A |
Richard and Stan, Richard, could you provide me with more detail on the position of the ribbons? Was there a single string of ribbons from front to back or were they staggared from window to bottom rail? Were the radiator opening ribbon(s) generally on the intake grill of the door or arranged at the leading edge to the intake? When you describe "standing out" my first impression was vertical, but I was jumping to a conclusion. Did Gene describe the ribbons in more detail? Au Contraire, Mr. Bowyer, the ribbons are a scientific approach as they permit someone to visualize features that are not normally visible. Stan, I agree with your observation on modifications but I don't see very often when converters change the basic layout of the cooling system "arrangement". Could you explain further or provide an example? | ||
| Chris 85 RTS Rating: N/A |
I have been told that the rear mudflap on an RTS is critical to proper cooling, and it spans the entire width of the bus behind the rear wheels. | ||
| RJL Rating: N/A |
Chris - Yup, that's right. RJ PD4106-2784 Fresno CA | ||
| Stan Rating: N/A |
Marc: The most frequent modification to the cooling system is a change in horsepower. Many people don't like the low HP setting on the original engine and use various methods to increase the power. Others do a complete engine change to higher HP engine. Still others install vented doors or panels or add or remove rubber flaps in front of, or behind the drive axle. Some change to a different rad with or without changing the fan. Some MCI owners change from the two top rads to one side rad. There are even those who try to run with only two 3200 CFM electric fans on the rad. If I took the time I could probably think of several more, but these are all mods to the cooling system. | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
I do not think Gene ever told anyone on the board. I believe it was posted here a couple of years ago. He used to be very active. I really do not think it matters exactly where the ribbons were. He indicated it appeared that the ribbons in the area of the radiator intake were standing out vertically at road speed. I am assuming they were sucked into the radiator area when the bus was stationary. He also indicated that with a front cover/door missing in the front of the bus that papers laying on the floor near the driver were sucked out the front of the bus at road speed. Richard | ||
| DavidInWilmNC Rating: N/A |
I've seen pics of louvered side doors on MC-7's and some -5's (and one -8 that has an 8V-92). I wonder if using louvers there would help those with hot-running MCI's. If this is a low pressure area on an Eagle, I wonder if it is on an MCI too. I haven't driven mine enough to know if it runs hot... actually I've driven it once... but there doesn't seem to be a lot of area for radiator exhaust to escape from the engine bay. In fact, one of those interior access panels in the rear floor of my -8 was loose and it felt like a furnace blowing through the gap. This was back in May and it wasn't really hot out, so it was definitely engine heat trying to escape! | ||
| niles steckbauer (Niles500)
Rating: N/A |
There's nothing to stop any of us from reproducing Gene's ribbon experiment - If I see him this summer I'll try and remember to ask him if his test was conclusive - I guess I'll be seeing a lot of rigs running down the road wit dem rainbow streamers on 'em - Niles | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Tom C. made a comment about replacing a windtunnel with a wind speed detector... Well, yes Tom, that would replace a wind tunnel if your intention was to read an air speed of an unknown temperature, pressure and direction across a small, single ray/line... The real replacement would be the ribbons (called telltales, which sailors put on sails in various places to give them an idea of "what the wind is doing" on the sail surface). The reason I advocated a windtunnel, is that you can set the humidity, temperature and the windspeed (or vary them at will) so that you can run your experiments changing only one variable (true to the scientific meathod) and the vehicle won't actually be doing 65. A better way to replace the wind tunnel would be to have several different configurations of your "slat" available for quick changes (vise grips, etc...) and different grille types pre-made, or easily changable. Then drive the rig like you would any other day, taking note of the engine tempurature and vehicle speed. But the key is to have "an eye" on the test, so a downward looking video camera and/or a chase vehicle with a video camera would be usefull. Another part of the test is logging the torque the fan hub is applying to the blades (this is one of the things I constructed to get the horsepower requirements for my new electric motor). A simple way to measure that, is a similar meathod used in reading shaft torque in helicopters: Phase-shift. You have a strobe light in tune with the fan speed, and using a hub with a spring of known compression attached to the hub, and two lines painted on 1) the hub, 2) the fan, you can measure the instantaneous diference of the angle of the hub to the fan required to achieve the speed (you can also use hall-effect pickups and an oscilliscope). Calculate that with the known spring force and ther you have it! As with most (truly) scientific experiments, data loggin is key here. And I mean everything you can put a sensor on! For a succesful fan drive change comparisons between: 1) Vechicle speed 2) Air Tempurature 3) Air Humidity 4) Rear Mudflap Placement 5) Rear Mudflap Type (full width or tires only) 6) Slat Placement 7) Slat Arrangement (if multiple slats) 8) Grille Type 9) Air Pressure Before Radiator (behind grille) 10) Water Temperature Before Radiator 11) Air Pressure After Radiator/Before Fan (inside the shroud) 12) Water Tempurature After Radiator 13) Water Flow Through Radiator (10,12,13 would be used to caluculate heat loss from water to air) 14) Fan Speed 15) Fan Torque 16) Engine Compartment Tempurature 17) Engine Compartment Pressure 18) Water Temperature Entering Engine 19) Water Tempurature Leaving Engine 20) Engine Block Tempurature 21) Exhaust Gas Tempurature Leaving Engine 22) Exhaust Gas Tempurature Leaving Engine Compartment 23) Exhaust Manifold Tempurature (13,18,19 would be used to calculate heat loss from engine to water - 20,21,22,23 would be used to calculate heat loss from the engine to its environment) 24) Engine RPM 25) Throttle Request Angle 26) Fuel Consumption Rate Etc... Etc... All must be time stamped (ie. using an IEEE-GPIB bussed system or a SMPTE Genlock time code interface) to ensure the samples are placed in the right part of the chart. Any time you change only one variable, one should run the speeds from dead stop (to get a reference), all the way to at least top speed. As you can see, having the sensory attatched would pose one risk, then taking the time to change one thing and find a stretch of road where you could run the vehicle for any length of time to stabilize the results all the way up to top speed +10-20% (or prove thermal runaway is occurring) would be hell on the driver and your wallet! Oh and this would be the best time to point out that true science in the face of all the data that must be collected (due to the sheer number of variables/controls) is self defeating. When one answers one question with a scientific meathod, one creates no less than one NEW question or variable (this could be seen as further proof that all questions, etc. are fractals). This is where the individual must separate ones-self from the work an decide when "enough is enough", or when the answer is correct enough for one to be sure of it reliability. The good news is, once you've done all of that, you know by reading fewer gauges that your engine is either opperating okay or not (or you could fix the clutch, and stick with the factory specs for what's normal ) Cheers! Tim (See Marc, I tried your meathod. I still think my previous post where I said "fix the clutch" was easier and more correct... -T) | ||
| niles steckbauer (Niles500)
Rating: N/A |
Tim - hope you don't mind if I chime in on your conversation - but the main thing that leads me to believe that electric fans of the type that were to be tested by a certain mongrel would not work is the environmental conditions not noted on your list above - side mount radiators are uniquely susceptible to cross wind forces for instance - think I-90 - an electric fan or 2 of the HP in the untested scenerio referenced above might be able to function at low speed with no/low crosswind, but arguably could stall in the types of cross winds found in the northern plains region - although the original bus fans may have been designed to put out up to 25 HP at maximum load - they are typically 'idling' when natural airflow is providing some or most of the flow through the rad - and therefore using drastically less HP than when under full load (I basically also have a problem with the contention that using the electric fans are saving HP anyway - just because the fans are rated at say 25 HP - we can't assume that they are using 25 HP - that is ludicrous - the fans are using whatever HP is needed to maintain the volume of flow and RPM under each specific condition)- the question is not whether electric fans of a low HP can supply enough airflow through the rad under a 'certain' condition, but whether it can handle the load under 'all' conditions - I'll readily admit that the full 25 HP is probably used less than 1% of the time - but the reserve HP built in the factory design is most certainly warranted to meet the 'ALL' conditions - Just my opinion, but I think its valid - Niles | ||
| David Hartley (Drdave)
Rating: N/A |
By the time you install all of the telemetry, gauges, computers, chart recorders and monitoring systems you could have just moved the radiator to the front of the bus, created a grill and air intake system and driven it hydraulically from a PTO takeoff on the tranny. Or, Just leave the engineering in the trash can, Fix the fan clutch, Buy a new flexi-fan and be done with it. The more you over complicate the plumbing, The easier it is to stop up the drain.... | ||
| Tim Strommen (Tim_strommen)
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Very valid thoughts Niles. I thought I spoke a blanket warning to the individual you are referring to on the July 11th, 4:12PM post with: "...I was mearly doing what he asked by submitting further suggestions that may help his situation in the event he was unable to resolve the fan clutch issue, and trying to disuade him from going through the expense, experimentation, and engineering which would be required to replace an existing belt system with a different electromotive system altogether (you hear that TD?)..." Further as an additional statement, I never suggested that I was saving HP with my electric setup, I was simply coming up with the most efficient conceivable system for either sharing the load (drag, wind resistance, etc.) of the radiator fan's function between my prime-mover and secondary DC-genset, OR placing the full load on one or the other power plants. My logic was simply: the engine already has to push this 40,000lb piece of metal up-hill, with a headwind, in 120 deg heat, why make it push the fan also? That's my only reason for going "my way". (Cross-wind was one of the 10+ "etc."s I came up with, but truncated) Cheers all! Tim P.S. Bravo Dr Dave, and Right-On! -T | ||
| niles steckbauer (Niles500)
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Tim - sorry - didn't mean to intimate that you were not knowledgable - to the contrary - when reading your posts its evident that you are VERY knowledgable, and although your explanations are plain and easily understandable, they still make my head hurt - LOL - but I'll keep learn'in if you keep teach'in - Niles | ||
| David Hartley (Drdave)
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When you get past 50, Things are never as sharp as they used to be... If I had started this bus thing for myself when I was 28, I would have been engineering everything in sight! And no doubt trying all of the impossible or improbable possibilities. I started with van conversions in 1969 and worked my way up to rv repairs and renovations, Then into satellite systems and into computers in 1978,That lasted until "forever", I have done ride and show control & projection system for Disney and Universal, And driven buses for Disney along with a lot of other things, I have been an engineer, technician, electrician, plumber and many other things. Having said I had been there and done that should be self evident. However I don't know everything yet and probably won't live long enough to learn it all. But its not a perfect world. | ||
| James Maxwell (Jmaxwell)
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jd: The '81 used an OEM fan clutch by Grmn/Flx. I also have one, and it displays similar problems. Have talked to 2 others w/ '81 models, all 6v92, and they too have the problem. The bigger problem: I have looked all over for a new set of clutch disc with no luck. I no longer use the bus, so I'm not as concerned as before, but my solution, should it be necessary, would be to remove the clutch assy., lock the plates, and put a glycerin thermostatic clutch directly to the fan blade. | ||
| David Hartley (Drdave)
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You may want to look for the Fan/Hub-Pulley system from an RTS, It replaces the hydraulic hub in about the same space. But it does add a belt and idler pulley to the system. | ||
| Sammy
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I have done 3 fan drive conversions on RTS'. It eliminates the original fan "torus" - no more leaks, more dependable, easy to service. I recommend trying to locate a donor engine to collect all the pieces you'll need. Great suggestion from previous post. | ||
| Tom Hamrick (Tomhamrick)
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The below message was posted on the Eagle yahoo group board by Harry Graybill who work at the Eagle plant. All of the doors on my Eagle are original and they are just as he says. Tom Hamrick To all. There is another factor that I have not heard about when it comes to the radiator cooling. I don't know if most of the radiator doors on your coaches are original as to the screen on the doors. When Eagles were manufactured the screening on the condenser and radiator doors were expanded metal mesh. These expanded metal screens were also used on the fresh air replacement doors on the each side of the coach. The mesh on these screens was installed with the expanded metal facing forward to force air into the radiator and condenser compartments also into the air replacement boxes. Believe it or not this makes a really big difference.If it didn't you could just use chicken wire. The screens were made of stainless steel and come in 4'x 8' sheets. There are other factors that can have an effect also, such as the number of blades on the fan or the pitch of the blades. How much ventilation you have in the engine compartment etc. We used to get some orders where the customer wanted the whole engine compartment sealed underneath the engine. If the air can't circulate properly it simply stays in the engine compartment and it would run hotter. |