ECT question

[yfzjim]

I have had my truck for about 6 months now and during the summer my ect would run at around 192. It is now running around 180 and my MPG has dropped about 3 or 4 mpg. Is this just due to the colder outside air and winter blend fuel or do I have a bad t stat? What is everyone else reading for ect during the winter. Im thinking my stat should be keeping me back at 192 no matter how cold it is outside.

[turbo347stang]

I would say replace the t-stat. MPG drop can be primarily blamed on the fuel, the high temp will make the engine run a little more efficiently.

[yfzjim]

I did a flush and switched to ELC couple months ago and I replaced the stat when I did it. I guess its possible that its bad out of the box. I cant decide if I noticed the cooler running temps as soon as I changed it....Will winter blend hurt economy that much? I was thinking that was definately part of it but also thought it may be partly to the cooler running temp and the PCM dumping more fuel to try to warm it up. Is that possible or do diesels not use more fuel when not fully up to temp?

[2 stroker]

Did you get the t/stat from Ford or the parts store new t/stat from Ford it should all come together (housing-t/stat-o-ring) in a box. The part number is RT-1169.
2 stroker

[yfzjim]

I got it from Advance Auto Parts. It did come with the housing and O-ring too.

[bft blue oval boys]

same thing going on here

[yfzjim]

Changed out my stat and Im now back to running at 192. Ill have to wait and see if it helps my mileage any.