Engine getting hot when towing my 31’ travel trailer. Dealer did a ride along and concluded that the fan clutch was bad and there was a restriction in the oil cooler. Replaced both, still getting hot. I’m not losing coolant. The fan is not cutting on when the temp gauge goes up. I hooked up my Superchip Flashpaq to monitor actual engine temp. Engine gets up to 242 degrees and the “check gauge” light comes on but no fan. This only happens when I am towing and it shifts into overdrive. If I punch the accelerator to make it downshift and get some more revs, the temp backs off. A/C still blows cold. Trans temp is perfect. Does anyone have an idea where to look next?

 

Are you saying the "no fan in O/D" only happens when you're towing, but cruising around it's fine in O/D? Was this on a grade?

 

If you're going up hill, that sounds about right. I made mine hold OD going up some hills pulling a 5500lb truck on my 18ft flat deck trailer. It shot up into the 240 range, but no CEL. However, when I had it loaded down (10K of trailer, Jeep, and mother-in-law's stuff on a commercial scale) doing a cross contry from Salt Lake City to Fallon on I-80 in June, unlocking the converter on hills kept the temps about 220 up hill.

In short, you're lugging the motor pulling that trailer in OD with the converter locked (assuming it's an auto), that's what caused my high temps pulling a load up hill.

 

The engine never gets hot when the truck is unloaded so I never hear the fan when the truck is up to speed. It is only when towing and it happens on flat ground. When I was towing yesterday from South Carolina to Maryland the outside temps were never above 60 degrees and the engine didn't get above 228. When I towed from Florida to South Carolina the day before the outside temps were close to 90 and the engine temp would climb to 242 in overdrive but if I got it to downshift they would go down to 232.

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It is an automatic. At 240 the PCM should be calling for the fan but I'm getting nothing. I've hauled loads much heavier in the mountains at 90 degrees and never got hot. This is a first.

 

What mods are on the truck?

Why not just tap the brake to get the torque converter to unlock?

You're not using that superchips for tuning and towing at the same time are you?

 

No major mods. Blue spring, AirRaid intake, 4" lift, 35" tires, AirLift air bags

I was towing with the stock tune. I use the Flashpaq "Towing" tune when I'm in the mountains. I use the "Performance" tune for daily driving.

I tapped my brakes all the way from Florida to Maryland to keep it from locking. Burned a ton of fuel. I've been towing campers this size since I bought the truck 8 years ago. Never got hot before. The truck didn't even run hot when I blew up the EGR cooler two years ago while pulling the same camper.

 

I'd look into better tuning, though that's most likely not your issue, but it's not helping anything.

Probably time for an oil cooler rebuild. Monitor oil temp against coolant temp, it should never really spread more than 15* apart.

Coolant filter, coolant flush, and a new oil cooler are probably in your future (at least, this is what I would recommend you do) and then some better tuning. Are you still running an EGR cooler? I'd do an EGR delete too.

 

I just had a new oil cooler put in last week.

I just ordered a coolant filter kit. I am running an EGR cooler but it is a Bulletproof aftermarket one.

 

Ok, good foundation.

Guess I should have read the first post again. You did put a new oil cooler in!

I know it seems elementary, it might not hurt to clean the outside of the intercooler and radiator. My buddy bought an 05 that had similar issues and would get hot quick out of no where. Took a pressure washer to the radiator and intercooler and we couldn't believe the dust and dirt that came out of there. It never did it again after the cleaning. Wouldn't hurt to check...

 

No biggie.

I will certainly take that advice. There are a few layers of coolers on the front of these things. They could easily be blocked a bit. I'll keep my fingers crossed.

I talked to the tech that did the oil cooler and he called some tech friends and someone told him that it could be the water pump. Something about the crap in the coolant wearing away the impeller. Ever heard of anything like that?