Engine thermostat?

[BobT]

I have a 2001 Ford F-150 with a 5.4L V8. Ever since I purchased this vehicle new I noticed that the cab heater/defroster didn’t really put out the kind of heat I had come to expect from my vehicles. I just figured the OEM probably installed a low temperature 160 degree thermostat and short of changing it myself, I decided to live with it. It worked okay but not great, especially for a MN winter.

By watching the engine temperature gauge I could tell that the thermostat was functioning because engine temperature did rise to a common set point. The gauge does not display actual temperature but is only a pointer. At least it’s a gauge and not just an one-who-thinks-I-am-silly light. Lately however I have been noticing that the engine temperature hasn’t been getting up to “normal” and my cab heat is no longer adequate. From this I believe my engine coolant thermostat must be getting weak. It still brings the engine temp to a common setting but not as warm as it once did.

Does anyone know what the recommended temperature thermostat is for this 2001 5.4L engine? Over the years I have always believed that for best efficiency and performance the hotter the better so long as the coolant doesn’t boil. This seemed especially true with today's lubricants that are better equipped to prevent thermal breakdown. For this reason I usually installed the 190 degree thermostats in my engines. A side benefit of course is the nice hot output that comes from the cab heater.

I hesitate to use a high temperature thermostat in this particular engine because somewhere in the archives of my memory I have the idea that someone told me that Ford didn’t recommend using the hot thermostat in this particular model/year engine. Supposedly the heads are made from different material than the block and therefore expand at different rates as the engine heats up. Using a hotter thermostat introduces the potential for premature head gasket leaks due to these different expansion rates. Is there any truth to this or is it hogwash.

Thanks,

Bob

[Jeremy airjer W]

195 degree

The only vehicles that I am aware of that use cooler stats are some of the older sebring/stratus with the 2.7 liter v-6. They used a 180 degree stat. Just about everything else is pretty standard with the 195 degree.

[BobT]

Thanks.

Bob