Towing overheat today.

[Jackpine]

Originally Posted by Kwattro

I've ordered a FoMo Racing rad, along with a 195* higher GPH t-stat , new belt, new cap, and some Amsoil coolant. I'll probably replace the fan clutch while I'm in there since it's not too expensive. No evidence of a head gasket failure. I'll take a gamble on the pump because I just don't see that failing at 40k miles, especially with a welded steel impeller, but who knows. Pretty sure is the t-stat but it gives me an excuse to do some upgrades while in in there. Will post pics when I get everything in.

Your T-stat would have to be sticking in a near closed condition to give you those symptoms. I'm certain they are designed to fail in the full open position. I'd tend to suspect the water pump, but I would not expect the rapid drop in the CHT value you experienced when you stopped to check. When my CHT has gone up (due to towing under load), it's taken quite a while to drop back down.

I think you may have a faulty CHT temp sensor. The ECT is derived from the CHT and if the sensor is sending a "hot" voltage value, you're going to go into failsafe mode (which is what you did). The failsafe CHT value is 258, so the 260 you saw would definitely give those symptoms.

- Jack

[88Racing]

Hmmm?
Sounds vaugly familier.
Before you were going to tow.
Did you happen to load the tow tune and then open the custom option menu for the first time?
Any dtc codes?

[Kwattro]

Originally Posted by 88Racing

Hmmm?
Sounds vaugly familier.
Before you were going to tow.
Did you happen to load the tow tune and then open the custom option menu for the first time?
Any dtc codes?

No DTC's on the truck. I run the 87 tow tune full time, so no changes made there. I didn't play in the custom menu either. Zero issues when not towing. Still waiting on my parts to arrive....

What sounds familiar to you. Are you experiencing the same thing, or have before?