Bell B40C Heating Issue

[Nige]

An off-the-wall thought but I’ll throw it out there anyway. If that Merc engine is used in all sorts of applications is there more than one type of water pump (LH or RH rotation) available for it and you’ve got the wrong one.? I guess your engine rebuilder would be able to answer that.

 

[631G]

An off-the-wall thought but I’ll throw it out there anyway. If that Merc engine is used in all sorts of applications is there more than one type of water pump (LH or RH rotation) available for it and you’ve got the wrong one.? I guess your engine rebuilder would be able to answer that.

Nige,
That's an excellent point. I would even bet that there could be different flow rates for the engine. Crane vs haul truck would have much different needs for cooling I'd imagine. I am going to look into this some more. Thank you for the idea to chase down.

 

[631G]

An off-the-wall thought but I’ll throw it out there anyway. If that Merc engine is used in all sorts of applications is there more than one type of water pump (LH or RH rotation) available for it and you’ve got the wrong one.? I guess your engine rebuilder would be able to answer that.

Following up on this on going issue. We have gotten the engine rebuilder involved on this engine now because we have replaced the temp sensor and gauge, fan clutch, thermostats, water pump and sent the rad out to be rodded and vatted and we're still over heating when the engine is loaded. They're asking around their staff to see what they think it could be, but they have thrown out two items that I'd be curious to get your thoughts on. They said that the impeller on the water pump could be slipping on the shaft as engine speed increases or there could be an air pocket in the block. I could see the impeller slipping being a possibility because the truck wont run hot until its put under a load and the RPM's are run up. The shop manager said it was a common issue with some of the Cummins engines used in on highway applications so maybe that happening here? To check this I guess we would need to pull the pump off and check that the set screw (if it has one) is tightened up? If we were to check for an air pocket in the motor how would we go about getting at that? Would the air not be absorbed into the coolant over time? This has gone beyond frustrating at this point.....

 

[Dave Neubert]

Normally if you can bleed the air from the highest point it will get the air out if it has a after cooler you need to loosen the water line untill water flows out Cummins has a petcock to do this. I would think if it was a air bubble it would heat no matter what

 

[631G]

Update on the engine saga. The company that did the rebuild has asked us to pull the exhaust pipes off the manifold and run the truck this way and see if there is restriction causing over heating. We plan to try this later this week after we get the water pump back on after having checked it again and confirming its not slipping.

I also had another idea thrown at me which is the fuel system could be running too lean and thus causing an over heat? Does this sound right? I am not even sure where to start on how to check the fuel to air ratio?...

 

[Vetech63]

Answer these for me since I just found this thread
1. How does the engine run? Is it smoothe through the rpm range, unloaded and loaded?
2. Is there excessive black smoke out the exhaust when under a heavy load?
3. What is the hottest temp you have seen with the ir gun at the thermostat housing versus what the gauge is showing at the same time?
4. Is the temp sender near the exhaust and is the exhaust leak free?

The thermostat is a water flow and temp regulator. Its job is to keep the engine at a specific temp range and adjusts the water flow accordingly. The coolant in your system absorbs heat......the airflow through your radiator cools the coolant.
Being that from what I have read so far.....it sounds like the timing may be a bit off under the engine load and creating excessive heat.

JMHO of course

 

[Dave Neubert]

On diesels if you were running lite on fuel it would kill the power and the turbo boost. Does it have low power you could check the boost pressure and see if it is low or not

 

[631G]

Answer these for me since I just found this thread
1. How does the engine run? Is it smooth through the rpm range, unloaded and loaded?
The engine does run smooth while the truck is both loaded and unloaded.
2. Is there excessive black smoke out the exhaust when under a heavy load?
No, no excessive smoking
3. What is the hottest temp you have seen with the ir gun at the thermostat housing versus what the gauge is showing at the same time?
While shooting the hot side of the radiator we read 190F. This was at idle after coming back from power breaking the truck and the temp had already came back down. The gauge vs the IR gun were reading the same. We also replaced both the gauge and sending unit to try and rule out a faulty temp sending unit and gauge. Looking at the gauge in the cab however the temp will run up past 215-220F.
4. Is the temp sender near the exhaust and is the exhaust leak free?
We have looked for exhaust leaks and found none. We thought that this too could be an issue but so far have found nothing.

The thermostat is a water flow and temp regulator. Its job is to keep the engine at a specific temp range and adjusts the water flow accordingly. The coolant in your system absorbs heat......the airflow through your radiator cools the coolant.
Being that from what I have read so far.....it sounds like the timing may be a bit off under the engine load and creating excessive heat.
I will call and check with the engine rebuilder I used and ask them about this. Wouldn't an out of time engine run poorly given this is a diesel engine?

JMHO of course

 

[631G]

On diesels if you were running lite on fuel it would kill the power and the turbo boost. Does it have low power you could check the boost pressure and see if it is low or not

Power has seemed to be fine. When I ran the truck in the spring it pulled fine to and from the fill. I have not checked out the turbo pressure. Will have to look into this one more to come up with a way to test it.

 

[631G]

We disconnected the exhaust today and ran it around some then power braked the unit on a hill and we did not run hot. The highest temperature we got up to was about 95C. So far as we can tell we might be able to live with a temp. of that range while hot. We plan to go ahead and straight pipe the truck and put it back into the field. Maybe we have finally solved this on going issue... time will tell.