Engine overheating under load on hill

[MarvGibbs]

My vehicle has an Edge monitor when towing a light load climbing a hill at highway speed the Edge monitor indicates the temperature climbs to 240 degrees and the indicator light on the dash also illuminates. I back the throttle off and the temperature immediately drops back to around 218 degrees which is close to the normal operating temperature for this truck. It seems that if the engine were truly overheating that the temperature wouldn’t drop that quickly. The fan clutch has been replace and I’ve verified that it is working.

I am hoping that someone can provide ideas for what is possibly causing this problem. Thanks

 

[AH64ID]

Have you replaced the thermostat? I have seen them not fully open.

 

[CharlesinGA]

Get a genuine Cummins thermostat. I had a NAPA thermostat sticking intermittently, bought a Cummins one and it works perfectly and runs cooler than the NAPA one ever did.

 

[Darkbloodmon]

Has the cooling system been opened at all? Air pocket from coolant loss?

 

[MarvGibbs]

I have a Cummins thermostat on order turns out they are not very simple to find. The truck doesn’t get driven often and the problem seems to occur when driving over long hills. Then engine was rebuilt about 35,000 miles ago. Not sure when the problem first started to occur but I’ve been dealing with it for a couple of years now. There are a few hills about 50 miles from my home base were I can test the new thermostat so in a few days I will replace the thermostat and take the drive towing a small load to see if the problem is fixed.

Thanks for your suggestions I will post back once I have completed the test.

 

[Ozymandias]

Did you hear the fan roar when the temperature went out?

 

[MarvGibbs]

The fan does roar when the temperature increases and backs off when temperature declines.

 

[Ozymandias]

Good, so it's in working order.
Thermostat seems to be bad then.

 

[BigPapa]

Then engine was rebuilt about 35,000 miles ago.

What happened? How many miles on it then?

 

[MarvGibbs]

Malfunctioning K&N air filter dusted the engine at 150,000 costly mistake. The truck now has the stock air filter and 185,000 miles.

 

[truckbouy2]

My truck is a 2003 about in 2006 I had issues with heat with the truck under load. Tried everything, still issues. Then I stumbled across an article by a transmission gentleman named Tim Holt in 2006 referring to the thermostat in the transmission cooler. Removed it, never had an issue in 16 years. I thought I'd have warm up issues because I live in Northern MN near the Canadian border. Truck runs just fine only issues I have is rust.....

 

[mweiman]

What about condition of radiator. Most common cause of what you are describing that I see is dirt blocking air flow across the radiator. You may have to remove it to get good access to clean it.

 

[Mhennessy]

My truck is a 2003 about in 2006 I had issues with heat with the truck under load. Tried everything, still issues. Then I stumbled across an article by a transmission gentleman named Tim Holt in 2006 referring to the thermostat in the transmission cooler. Removed it, never had an issue in 16 years. I thought I'd have warm up issues because I live in Northern MN near the Canadian border. Truck runs just fine only issues I have is rust.....

If you remove the trans cooler thermostat then the ATF will take the path of least resistance and bypass the cooling fins. Guys will "block off" the bypass tube by flipping thew thermostat, putting a plug in or picking the tube.
But this is not relevant to the OP's overheating engine.

 

[truckbouy2]

If you remove the trans cooler thermostat then the ATF will take the path of least resistance and bypass the cooling fins. Guys will "block off" the bypass tube by flipping thew thermostat, putting a plug in or picking the tube.
But this is not relevant to the OP's overheating engine.

250,000 miles pulling a skidsteer, dump trailer, countless car trailers, up hill, down hill, around the hill, in HOT , cold, snowy, rainy, all kinds of weather, and transmission STILL works like it's new. and YES it effected the truck overheating. Your least resistance theory, I'd rethink it......

 

[Mhennessy]

250,000 miles pulling a skidsteer, dump trailer, countless car trailers, up hill, down hill, around the hill, in HOT , cold, snowy, rainy, all kinds of weather, and transmission STILL works like it's new. and YES it effected the truck overheating. Your least resistance theory, I'd rethink it......

Its not a theory its how it is designed. The ATF bypasses the cooling fins until the temp activates the thermostat that "pops" out and blocks off the bypass tube forcing the ATF into the cooling fins to be cooled. If you remove the thermostat all together from the cooler the ATF bypasses the fins very little is ATF is sent to the fins. If you block it off or "pinch" the bypass tube then it is forced into he cooler. Some guys remove the thermostat and replace it with a bolt, flip the thermostat or pinch the upper tube to achieve this. There are lots of articles regarding this mod.
I also tow a skid steer, dump trailer, 14k fifth wheel and enclosed trailer all over the western rockies and the thermoset sticking open and the trans heating up resulted in me "flipping" the thermostat to keep her cooler.
If your thermostat is just "removed" than you are not utilizing the front cooler effectively and putting the work load exclusively on your heat exchanger.

 

[MarvGibbs]

Okay, so I replaced the thermostat with a 190 degree Cummins thermostat and after extensive driving over many hills while towing the temperature on the Edge has not risen above 215 degrees. I have to say that this solved my problem and have to thank all for your help. A bad thermostat was the cause of this problem.

 

[Rowdy Dalton]

Okay, so I replaced the thermostat with a 190 degree Cummins thermostat and after extensive driving over many hills while towing the temperature on the Edge has not risen above 215 degrees. I have to say that this solved my problem and have to thank all for your help. A bad thermostat was the cause of this problem.

It only took you a year to listen to a fellow members advise. Well, better late than never.

 

[MarvGibbs]

It only took you a year to listen to a fellow members advise. Well, better late than never.

I changed the thermostat as soon as it was posted and I received the new thermostat. Family health issues prevented me from leaving town where I could test if it solved my problem. Now that health issues were resolved and I was able to travel again I validated that the problem was resolved. Sorry it took this long but for anyone having a problem like this I wanted to post that this solved my problem.