ive got a 2001 dodge that i pull a 50 ft trailer with and during the winter the truck runs fine never runs hot,as soon as it gets around 60-70 the truck runs hot on hills,its getting so bad that on a hill it will go to 220 and at 220 it shuts the throttle down till it comes down to operating temp,this problem showed up last year but went away over the winter months,but it is still here again now that it is getting hotter out,i thought it was the clutch fan cause ive never heard the thing so i bought a new one and now i hear it plain as day,so that was probably bad, but didnt fix the problem, so i changed the thermostat yesterday with a cummins thermostat and it seems to run cooler when im not loaded but didnt change it when i am,the radiator looks clean in side and washed the out side,i need help with this problem this is my living runninng this truck and i love it just right now cant figure it out,when i climb a hill it goes up if its a 1/2 mile to a mile it may or may not get all the way up but as soon as you get to the top and go down the other side it goes down to 190 , i thought head gasket but no compression in radiator it would be pushing out and it isnt, the truck is automatic, and has 190,000 miles on it, any help would be greatly appreciated,thanks

 

Pa Outlaw:

The culprit is your probably automatic transmission. The stock auto tranny will often run VERY hot as it gets old (sometime even when new). The Torque Converter is to blame. The stock TC is so loose that it generates a LOT of heat when the truck is not locked up in OD. So here's what's happening:

You pull 50ft trailer with Automatic. NO problem on level ground. You hit a hill, and the tranny unlocks the coverter to get more power. With no lockup, you're now in fluid coupling under load, where the stock TC makes a LOT of heat. I'm talking tranny temps that can approach 300 degrees!!!

Your super-hot ATF then goes through the radiator, and instead of being cooled by the radiator, it actually HEATS the coolant. There's so much heat that the radiator can't keep up.

Then you see the high coolant temps-- caused by your tranny.

The solution is an aftermarket torque converter and valvebody. This will also make the truck put down the power a LOT better (more mpg, more response) and run cooler. Right now, you floor the pedal and won't go anywhere because the stock converter is so slushy. A new aftermarket TC fixes all that.

I would check out ATS diesel transmissions.

www.atsdiesel.com

Justin

 

thats a good theory but i dont know if i agree. if the tranny fluid were getting that hot you would have kissed it good bye a long time ago.

since you have changed most everything and the rad appears to be clear i would still think about the head gasket.

 

You might want to check your fan clutch,,,motor will over heat if it goes bad and will normally show up on hills not on flats roads........Pete

 

ive replaced the fan clutch last week, and it was bad, didnt fix the problem, as far as the trans i agree some what but on the diesels they dont run the trans fluid thru the radiator it has a oil cooler on the side of the block instead,my trans is new i had it rebuilt with a towing converter 3 months ago and they flushed the system,head gasket theory, well i kind of agree a lil but,if it were to be building heat from gasket i would have a bit of coolant pushing out the cap or oil in the coolant or vise versa, this is driving me nuts and i appreciate any help,i just got done draining more antifreeze and addding water in cae it had too much antifreeze verses water, im trying and dont worry when i find the problem ill post it,i do believe the trans could have some help in the matter though, thanks guys any more suggestions will be tryed

 

You might have a radiator shop clean and rod the radiator. It doesn't take much buildup to cause problems and the passages are really small. How about the thermostat?

 

replaced thermostat yesterday too

 

have you soked dwn the a/c unit and rad with Super clean a few times and blown it out backwards??

 

thumper i went to the car wash and spent 5 dollars hosing thru the radiator both ways to clean it but im going to go tomorrow and hit it with super clean and see what i get im thinking trans cooler on the side of the block,its just pushing more towards that every day , head gasket doesnt seem to be the right answer to me either,ive got all the tooling to do everything on these but got to know what to fix before you fix it thanks

 

here is ez test.unhook top and bottom hose,cap off bottm hole,fill rad with water - leave cap off too
unplug bottom hose.........water has to gush out and be done in about 3 sec....depends on size of rad ( apply some logic here)
the pt is it has to emty in a HURRY!
this is a qulified test that most rad shops use w.o. tying up alot of time in equpment.
the neat thing about this is it can be done in the truck

 

Before you count out your radiator , you should get a heat gun , you can find em now for much less than a hundred dollars , and check the temperature across the radiator from the inlet to the outlet when it is hot , there should be about a 20 degree drop across , if it is more then most likely it is plugged and slowing the flow.

 

does the motor seem overheated. it could be something as simple as a bad guadge or sending unit

 

i checked with a heat gun, water kneck is exactly what the gauge said, its either head gasket radiator or transmission cooler on the block,if i do all of them and it isnt fixed it will be for sale

 

Take a sample of the antifreeze for a litmus test.

 

start with the rad it should be the easiest and cheapest. i really dont think its the tranny...