nvillagrana

I have a 2001 Dodge Cummins Auto and the truck overheats when put under load. THe local shop has checked everything and they say it all checks out. THe fan clutch was replaced when this first started but it didnt change anything. My concern with the fan clutch is that it has some play in it. Ive asked a few people and some say its normal while others say its not. Any advice would help. Thanks

blizz

Clean the rad and i put a 180 degree stat in .

nvillagrana

I cleaned the radiator and the thermostat has been replaced but not sure if the thermostat is a 180 degree stat. Does your fan clutch have some play in it blizz ?

dozer12216

Yes there is small amount of play in blades. Normal. Is it really O'heating or just getting higher than you expect? 220 degrees under load is not that unsual under heavy load, say pulling a long grade. Gear selection is critical. If keep in OD the lockup clutch will unlock and generate great heat. Drop back to "OD off" and let it run in direct lockup. When you pull down below about 45 go down to second gear and let er rev. When the load is great and pulls down to about 30 MPH go to first gear and let er wind to 3000 or perhaps 3200. You want to keep engine RPM up to keep converter slipping as little as possible. I had to pull 35000 gross up seven miles of 6-8 degree slope with no ability to stop. It may have hit 225 for short period. This is when syn oils do their best job of protecting components.

nvillagrana

It gets to far right of the gage and the engine derates. I pull a boat (17ft about 2500 lbs) in the mountains and just as it hits a grade the temps shoot up. The OD is off and the rpms are at about 3000-3200.

nvillagrana

Oh and the gages have been checked, there is no problem there.

J BODY

describe: "clean the radiator"

nvillagrana

Took it off from the truck and cleaned it with a pressure washer. Also relocated the breather hose to prevent any future build up on the radiator.

dozer12216

With a 2500 # load the unit should pull Saint Helens in OD. Assuming the radiator is actually clean, the next test is actual flow of coolant through the radiator. A good radiator shop can test radiator flow with unit removed. They may have a total coolant flow tester that is hooked up in place of uppper radiator hose. It also test for oil and combustion gases in system. There is also a block checker that test for combustion gases in cooling system.
Based on description so far, a good case for head gasket leak is building. The other possibililites is a cracked head or water pump not capable of movin enough water (impeller bad).
The best I can do is set on sideline and make suggestions, that hopefully have some revelance. JMHO

nvillagrana

The water pump has been replaced and the shop tested coolant flow and all turned out good. Not sure if they tested for oil and combustion gases in the coolant though.

Stormin_Norman

could the TQ clutch be slipping and causing excessive heat

Busboy

X2, my money's on the transmission side.

Mike Cole

I have been chasing this same rat. Cleaned rad, flushed system,new stat.
I am going towards the heat coming into the cooling system from the tranny. I ahve installed an electric fan cooled transmission cooler. I dont have a report on it yet because it only occus when I pull the 5th wheel up a long steep grade, but I will let you know. Next step would be the bigger "in the bed" cooler, which I hear holds about 18 qts of fluid. I think you might need to bypass for winter drining, so I will put 3 way valve if I do this. Let me know whay you find.

nvillagrana

Yeah I believe that everything that needs to be checked has been checked. My probable next step is to replace the radiatior, it supposedly checked out fine but it could be corroded internally causing the heat transfer to decrease.

dozer12216

If it passed a coolant flow test as you said, the rad should be O'K. Another test for pluging is after warmed up, shut engine off and feel radiator for temp difference over back side of it. If an area is cool caompared to rest then that area is restricted. Remember the combustion leak test also.