| Author | Message | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1302 Registered: 1-2003 Posted From: 67.45.240.154  Rating: N/A |
Folks, I need recommendations for a decent radiator shop that can test and possibly re-core a small radiator on a Kubota-powered generator set, and also a shop that could, if needed, hoist the set out of the bus, pull the head, diagnose any issues found there, and install a new head gasket. Both of these places need to be in or near Las Vegas, NV. Reason: As some of you may already know, we are in the Las Vegas area for the next three weeks. While we are here, I have been helping friends and fellow bus nuts Ben and Karen with their problematic Kubota-powered Power Tech generator. (Some of you may know Ben as the fellow who is converting a Flxible Starliner, and while that is being done they are living in a Prevost Liberty Classic Lady.) I have the generator portion of the set, as well as the control system, working perfectly. However, there are two issues, possibly related or possibly not. The first issue is that after it has sat for a while, say overnight, the Kubota will overheat shortly after startup. It would seem that air is ingressing into the system, and a giant air pocket at the thermostat housing (or maybe in the water pump?) is preventing coolant circulation. Unsurprisingly, the overheat switch, attached to a cooling passage in the head, quickly reaches the set point and shuts the unit down. Every time this happens, I am able to bleed the system (although sometimes it takes more than one try), refill it, and get the set started. Once the system has been fully bled, the generator runs fine, will stay running for hours, and has good coolant circulation through the radiator. Shutting it down and restarting it within a few hours is also usually successful, perhaps because it has not cooled far enough in the daytime temperatures for the pressure to drop sufficiently in the system to draw air into it. In addition to lots of 15-year-old hoses and clamps, there appear to be a couple of pinhole leaks in the radiator itself. Any of these might be the source of the air ingress, so we'd like to get the radiator tested and repaired or re-cored along with all the hoses changed out. Thus the radiator shop recommendation. The second issue is that, in doing this work, I have noticed the coolant has a slight brown tinge to it. It is possible that this is just rust and/or dirt from years of neglect, or maybe adding red coolant to a green system, but it is also possible that it is due to products of combustion in the coolant, possibly indicative of a broken head gasket or worse. If that's the case, it is also possible that this is the source of the gas bubbles in the cooling system. I have recommended that he get the coolant tested, along with the oil. If either reveals signs of cross-contamination, then we will need a qualified Kubota mechanic to pull the head and have a look. Any and all suggestions, recommendations, and comments are welcome. Post here or feel free to email or PM me. We want to get this work done between now and around March 13, so that I can be available to go to the shop with him and talk to the techs. Thanks. -Sean http://OurOdyssey.BlogSpot.com | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 1643 Registered: 3-2007 Posted From: 76.4.118.163  Rating: N/A |
Sean is this cooling system for the genset tied into the, like webasco unit?? Maybe something there also gomer | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1303 Registered: 1-2003 Posted From: 67.45.240.154 Rating: N/A |
No, it is a stand-alone generator system. -Sean http://OurOdyssey.BlogSpot.com | ||
| Ralph Peters (Ralph7)
Registered Member Username: Ralph7 Post Number: 215 Registered: 3-2004 Posted From: 75.226.62.184 Rating: N/A |
Testing the coolent yes, but do not know if the same co2 test for gas engines works for diesel. You are correct air can enter if the (leak) crack/loose hose on the intake side of the water pump, similar to air getting into a diesel line but not leaking liquid. Call Dick Wright? he built/builds those. Others on here know him better. Can you see/smell coolent in exhaust? Does rad have a pressure cap that is allowing pressure to escape and not build/over pressure to tell you of problems. | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 1010 Registered: 11-2004 Posted From: 173.78.31.252 Rating: N/A |
Sean - does it have a surge tank? Could be the tank, cap or fitting(s) need replaced = HTH | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1305 Registered: 1-2003 Posted From: 67.45.240.154 Rating: N/A |
Yes, it has a surge tank which is working normally. The radiator cap was marginal and I replaced it. I had to go to 13 because I could not source a 14. I really feel the air is entering either through the old hoses or through pinholes in the radiator, which is why I want a radiator shop to go over it, replace all the old hoses, repair, replace, or re-core the radiator, and pressure test the system. All of those things are beyond my limited capability here at Lake Mead. -Sean http://OurOdyssey.BlogSpot.com | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 2287 Registered: 12-2000 Posted From: 174.89.178.13  Rating: N/A |
I prefer to drill a small hole in the base of thermostats, out in the open away from the gasket, if it doesn't come with one, in order that an air pocket trapped under the thermostat may be pushed through by the water pump. If there begins to be air intrusion of some kind, at least overheat is avoided. That's the best I can do for this one. happy coaching! buswarrior | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1307 Registered: 1-2003 Posted From: 67.45.240.154 Rating: N/A |
FWIW, the Kubota 'stat already has such a hole, but that is a good point for anyone else reading the thread. -Sean http://OurOdyssey.BlogSpot.com | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 2276 Registered: 10-2003 Posted From: 71.58.71.157  Rating: N/A |
pressure test the system to find and leaks. Pinhole leaks in radiator or hoses will show up. Sounds like a head gasket or cracked head to me. can you run it without the cap to check for coolant pushing out? Does the cap have the little check valve on the bottom of it to allow system to draw coolant back into engine after it is shut down and cools off? | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 458 Registered: 3-2010 Posted From: 75.247.248.102  Rating: N/A |
gas bubbles in the cooling system is generally a cracked head ( magnaflux Head or bad head gasket). Both would create an over heat problem. Is the brown all brown as in rusty water. ( rusted out tanks and or tubes, so have roded or re-core) You can see it, If you drain some oil out of pan you would also see water in it.Oil in water would look just as that and not mixed. As Ralph says you would also smell a sweet antifreeze smell coming out the tailpipe if it was a crack or head gasket. Dave (Message edited by chrome_dome on February 20, 2012) (Message edited by chrome_dome on February 20, 2012) | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 634 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
I am with Dave, bubbles showing up in the cooling system would indicate headgasket/ cracked head. Joe. | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1309 Registered: 1-2003 Posted From: 67.45.240.154 Rating: N/A |
Ok, John, Dave, and Joe, please explain your rationale for leaning towards cracked head or gasket. The consensus on the other board seems to be the other way -- just a leak in the system and no head/gasket problem. The reason is that gas bubbles from a cracked head or gasket would find their way into the system while the engine was running. Eventually, enough gas would get in there to cause a shutdown. However, in this case, once we bleed the system and get it started, it will run for hours and hours with no problem -- I think at one point we ran it for eight hours before the Liberty's crappy autostart system decided the batteries were charged and shut it down. Even then, it started right up again after another few hours. It's only when the system cools down overnight to stone cold where we are getting an air bubble in the system. Thoughts? -Sean http://OurOdyssey.BlogSpot.com | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 2281 Registered: 10-2003 Posted From: 71.58.71.157 Rating: N/A |
my experience with auto diesels is that the air insulates the sensors from heat and might not indicate overheat. Can you pressure test the cooling system? No relief button on bottom of rad cap? | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1311 Registered: 1-2003 Posted From: 67.45.240.154 Rating: N/A |
The overheat sensor is working just fine, shutting the engine down. I have no means to do a pressure test, which is part of why I wanted recommendations for a good radiator service shop. There is no relief button on the pressure cap -- it's the old-fashioned style. -Sean http://OurOdyssey.BlogSpot.com | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 2282 Registered: 10-2003 Posted From: 71.58.71.157 Rating: N/A |
as it cools down overnight, it is going to want to draw coolant back in from the overflow bottle. The cap needs that little cap on bottom that opens and allows coolant to go back into radiator. If it can't do this, it will pull air in somewhere at a hose or water pump seal. That check valve opens under almost no vacuum. It seals for pressure when engine is running. You need this type of cap if you are using a coolant recovery bottle. However, some engines use a pressurized bottle with no cap on the radiator, but on the bottle, outlet on bottle connects to suction side of water pump, and coolant is fed into bottle from an engine coolant port at top of engine. My TDI Jetta and Silverado diesel use this system. I'm not sure why they went to this, but a slow leaking head gasket or head doesn't affect engine operation.The air will stay in top of bottle. When the engine is hot and running in either system, you will see occasional or frequent air bubbles coming up through coolant in the bottle if the head/gasket is leaking. BTW, does this engine have a temperature gage? | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1312 Registered: 1-2003 Posted From: 67.45.240.154 Rating: N/A |
John, sorry, I misunderstood what you meant by "relief button" -- I though you meant something you pressed. Yes, the cap is a standard pressure cap, which lets coolant flow to or from the expansion tank. It is working fine. The temp gauge is inop -- I have been using an infrared pyrometer to read temps at various points around the system. -Sean http://OurOdyssey.BlogSpot.com | ||
| Dave Walker (Chrome_dome)
Registered Member Username: Chrome_dome Post Number: 460 Registered: 3-2010 Posted From: 75.208.26.48 Rating: N/A |
Sean the reason I think it is cracked head or more probable a head gasket leak is just what you are explaining and very well I may add. When it is cold and you start it up it has had the time to suck in air Somewhere. It then overheats. You bleed it and off you go with a fully heated engine running fine. If you don't bled it and it keeps overheating what would happen? It would probably hydrologically lock up because the head would warp and water now enters the Cylinder.Being you know better you bleed off the air and it runs well no head warp and no water in cylinders. But if it does it enough it will eventually do it. I drove my truck to Tahoe from Sacramento for a week and every day it would run fine going up in the cold air. coming home after work in the warmer temps I would start missing and shake a little. I had bubbling in the radiator like gas bubbles popping. I bled off the air and made it home. When I finally had time I checked the oil by draining some into a clear bottle and the was water in it. I check the water in the radiator and there was oil in that. I pulled the head and had it check and it was warped and had it shaved and polished put it back on with new head gasket and never had the problem again. | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 1676 Registered: 10-2006 Posted From: 67.238.59.158  Rating: N/A |
The folks with the most Kubota experience are probably at the local Carrier or other big truck reefer shop. Visit them , usually their prices are great , and things like a second hand head would be plentyfull. FF | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1314 Registered: 1-2003 Posted From: 67.45.240.154 Rating: N/A |
So just a quick update here: I am still at Lake Mead, although we will be rolling down the hill to B&B Coach to fix a problem of our own later today (http://ourodyssey.blogspot.com/2012/02/not-what-we-meant-by-pop-rivets.html), and Ben brought his bus to a radiator shop in town yesterday afternoon. I spoke to the tech on the phone to brief him on what we had already done and the symptoms. They removed, inspected, and pressure tested the radiator, which turned out to be in good shape. They also removed and inspected all hoses, which also turned out to be fine. What had looked to us like age cracking in the hoses was actually in some clear coat that Liberty had applied to the whole system, hoses and all. We also learned that, while it is marked as an 11, the cap on the lower accumulator tank in the return line has been blocked off and so is actually solid, so the 14 cap on the radiator header at the high point in the system is the only actual pressure relief cap, connected to a proper (atmospheric) expansion tank. The shop drilled out the bleed hole in the thermostat to a larger size, and pressure tested the entire system, which passed. They backflushed the cooling system and took a sample of the old coolant for analysis. As of the last I heard last night, it was all back together and working. Of course, only an overnight cool down will tell us if a backflush, fill, proper bleed, and larger bleed hole in the stat will have cured the problem. As of this writing I have not heard back from Ben as to whether he's tried it yet today. I will update here when I learn more. Thanks for all the help. -Sean http://OurOdyssey.BlogSpot.com | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1315 Registered: 1-2003 Posted From: 72.171.0.145 Rating: N/A |
The last update on this for a while is that Ben and Karen split for Hawaii before he got a chance to test whether the work they did at the radiator shop cured the problem. Also, he could not get hold of a test kit before he left so even the coolant testing will have to wait a couple weeks for them to return. I am fairly convinced that the last remaining problem here was bleeding all the air out of the system. Clearly I was unable to do this in the field without the proper tools, or the ability to tilt the bus to whatever weird angle is needed to get those final air pockets out. I am hoping that the process they used at the radiator shop was more successful. When they get back on March 5 or so we will get a chance to re-test, and I will update the thread here if there is still a problem. -Sean http://OurOdyssey.BlogSpot.com |