I am having a weird problem with the V-10 in my 2001 excursion.

I believe that this problem started when the truck overheated while I was towing a trailer. After the truck overheated I replaced the radiator, thermostat and water pump.

Since then I have been having an intermittent problem. Occasionally the temperature gauge will immediately spike to full hot and the temperature warning light and CEL come on. The error code set is cylinder overtemp. The engine drops power and from my research I believe that it is turning off 5 cylinders to help cool the engine.

I do not believe that the coolant is actually getting that hot. If I turn the truck off and back on, it is immediately back at the normal temperature. It acts more like an air bubble hit the temperature sender.

When this happens, coolant is blown out of the cap on the expansion bottle. I have replaced the cap and expansion bottle with no effect.

Here is the really confusing part. This only happens when the truck is on max A/C. On regular A/C, I have driven thousands of miles without issue. I cannot drive more than about 20 miles without this problem occuring with the selector on max A/C.

What changes when the A/C is turned to max A/C?

I know that the heater control valve changes. I replaced the heater control valve and that did not solve the problem.

Are there hoses that coolant only runs through when the A/C is set to max? Air finding it's way into the system might be causing this?

Thanks for any ideas or help.

 

I had the same problem with my 04' This is what I did to fix it, I also replaced the clutch fan because it was going bad but I was still having the issue. So make sure that you only use the ford approved coolant and not just the stuff they sale at the auto parts store and replace the thermostat and make sure it is a ford thermostat and not one that you buy at the auto parts store. I replace my thermostat 3 times with the ones they sale at the auto part store and flushed the coolant system and was putting in the green stuff from the store once I flushed the system and switched it to the fords gold coolant and put a new ford thermostat I have had no problems since.

So in short I replaced the clutch fan, radiator and thermostat three times and green coolant and still over heated like you are have, with a/c on once I switched it to fords stuff never had a problem again. Hope this helps. Also buy several gallons of distilled water and use that when you mix the ford stuff and not tap or drinking water.

 

Only two things change: The inlet air motor switches to recirculate position and the coolant control valve changes to bypass the heater core.

Most likely, you do have a problem with an air bubble hitting the CHT sensor. The only two things I can think of that would cause that is a leak in the coolant loop that's letting air into the otherwise closed system when in MAX or there's a small head gasket leak. Only the first one makes any sense to me.

You can try manually bypassing the valve (remove it) and see if that solves the issue.

I can see no failure mechanism by which the specific coolant in use might cause this symptom.

 

I have a 2006 that did the exact same thing twice last year and only when the max air was used. Simce then I have not used max air and in over 20k miles pulling various trailer sizes it has not shown an overheat again. Would like to hear what you find that might fix this.

 

Sorry that it took so long to get back to this, but I have solved the problem. When the truck overheated, I put in a parts store thermostat when I replaced the water pump and radiator. That was the problem.

I put in a motorcraft thermostat and everything is ok now. I have driven a few thousand miles, including some towing, all on max A/C and nothing has gone wrong.

thanks for the help

 

Ridenred333 Hit the nail on the head Good call. Using Ford parts really prevents rework so it is cheaper to go ahead and buy ford parts in the first place Awesome of you to post your victory everyone benefits Thanks

 

Fully agree here ^^^! Always helpful down the road to someone.

Reps sent