I've noticed my truck has been running a hair over 190 around the city. Occasionally it will get around 200 but not often. I have noticed quite a decline in my mpg around the city and on the highway when the truck is running closer to 210 degrees i get upwards of 16-17 mpg. After reading more about the topic I've heard that the truck operates best around 210*. My question is do I have a faulty thermostat? I replaced in a little over a year ago with a motor craft one. I would like to get others insight and hopefully this is my mpg problem.

Thanks all

 

Factory thermostat is 195 (or maybe 192, can't remember). So running in the 190-200 range is right. If you're running at 210 regularly, something is wrong or you're working that truck pretty hard.

Mike

 

I was under the same impression. I read a couple threads who said they should be running in the 200-210*. I wish I had the link to the threads. Hopefully you're right. Thank you for the reply Mike!

 

yea i ben having something of the same issue ..

after i switched in my new thermostat it open right at the normal side of the temp gauge ..

it used to operate about 20% into the normal range and seemed to get better milage running slightly warmer .. just a little ..

i wish i remember what thermostat i used it was motorcraft from the dealership ..

i should have gone one step up i guess .. and too bad it's a pita go get to or i'd just swap it out ..

now with my ultra cool running aluminum plastic radiator it gets really cool .. sometimes running below 'normal' alot untill i really get on it ..

may get the higher thermostat .. just not a big rush .. what is the right one to get it running back into the 20% normal range again ???

 

I've got a good thermostat in there and an accurate temperature gauge(RTD100 probe). Once warmed up, it stays right in the 190F range; 185 to 195 fluctuations generally. Of course, that's unloaded; hauling up a hill can get much hotter than that.

 

+1 on 190 being norm. I don't have a "nice" gauge or probe but it's a real setup, unlike the stock setup which is basically a dummy light.

Once warm I peg 190 all day long until I idle too much or tow. But that's cause my fan never locks up. Ever.

As for fuel mileage, nobody ever got equal mileage in the city compared to highway. Just doesn't happen due to start/stop vs constant RPM efficiency. It's pretty common to lose 2-4 MPG in the city, just depends on driving style and the city(hills vs flat, how often you hit red lights, etc)

 

I run at 192, like mac said empty

 

awesome I feel much better knowing that I won't have to replace the thermostat especially since I just flushed my entire cooling system. Lol thanks everyone for replies!!