203 degree thermostat. Should I install one? 99-03 7.3

[glennhansel]

I read that installing a 203 degree thermostat will allow the engine to operate more efficiently and get better fuel mileage

Anyone have any experience with this?


From what I read, Ford took the IH design and installed a cooler thermostat than the original design.

Thank you

[JSchuricht]

Depends on what your drying to do. If your in a cold climate and want some extra heat or you just want to hear your fan run more often then go for it. If your towing a bunch then you might want to go the other way and use a 180 from Strictly Diesel.

[jesilvas]

I use the 203*. My doesn't run much more than it did before. Yea this summer but that's because it was 105 almost every day.
If it gave me better mileage, it is very very slight. MAYBE MAYBE .5mpg better. Doubt it. It does idle a bit smoother though since everything is a little warmer. Even if you go back to stock or cooler, put in a billet thermo housing. Much better than the stock stamped version.

[glennhansel]

Thanks for the reply. I've read that IH designed this engine with 203 degree thermostat and that it is most efficient in this temp range. Some people believe that installing a low temp thermostat is good, but my understanding is that in that case the engine will not warm up to its intended operating temperature.

Maybe someone can correct me if I am wrong.

The truck is located in Colorado, so hot weather is not usually an issue.

Don't know why Ford elected to go with the lower temp thermostat and why they elected not to install the coolant filter that the manufacturer designed into this engine. Seems like false savings in my book. Or am I wrong about this?

[jesilvas]

Yes the IH thermo is 203.
Yes, the IH water pump had a built in coolant filter mount.
They also put it into pickups, not busses and such.