My 99xlt coolant only 180 Degrees..low MPG?

[Strgzr]

Hey Folks,

Wondering if it is time for a new thermostat. My coolant temp stays at 180. never gets to 190 or above. MPG sucks at around 14 around town. MPG is much better in the summer. I am wondering if the thrmostat is opening too early or stuck open.

Even when it is lower than 170 degrees, the engine is in Closed Loop condition (taking O2 inputs) according to my Super Auto Scanner.

Thanks,
Strgzr

 

[MazdaGreg]

Sounds like it's getting weak and opening early. The coolant should be 195 at the upper radiator hose before it opens. Now it's not perfect, but you should swap it out with the factory rated one, which should be a 195. You will get better mileage, and it should run better. Mine used to sit on the C. Changed the thermostat, and all the difference in drivability in the world.

 

[mrboyle]

Like Greg mentioned, if the engine doesn't seem to be running as warm as it use to it sounds like its time for a new t-stat.
Another thing everyone needs to remember is, your gas mileage will always go down in the winter (unless you live where it never gets cold). For starters, you start your vehicle to let it warm up, there goes 1-2mpg per tank. It takes longer to reach opperating tempature, there's another 1-2mpg per tank. Most states now use "winter blend" fuels that don't seem to be as mpg friendly as the fuel used in the warmer months, there's a few more mpg down the tube. Eventually it all adds up and you think there is a running problem when in fact its just the way the game goes during the colder times of the year.

 

[MazdaGreg]

Oh, the winter blend. don't get me started... It will take a perfectly running truck and turn it to mush.

 

[Strgzr]

New therm stat installed

Installed the new therm stat. Temp is 192-201 now rather than the 182 I was getting before. Verdict is out but I hope my MPG goes up a bit. Napa guy (pretty helpful fella)thought it would with a 15 -20 degree difference. Pretty painless job on my 99 SOHC "E" engine.

Take care

Strgzr

 

[IAmTodd]

This may be next weeks project for me! Mine hovers right around 180*. And I'm getting a few MPG less than the other 5.0 guys. Thanks for the idea!

 

[Doug246]

Just put a new one in my 94 on friday..big difference in the heat output of the heater but what a job! Had to take off or move about 5 different parts.
Also the truck does run better now but havn't gone far enough to see if there is any difference in the milage

 

[CDW6212R]

Okay, who has an accurate temp gauge which shows accurate temps?

Engines run 10-15 degrees warmer than the rating of the thermostat. The rating is supposed to be when it starts to open. 160 thermostats are too cold, and over 180 is too hot of a thermostat. Those ranges are for climates that are extremely cold, or engines which run too hot. Operating temps should be around 195-200 for best efficiency, and power. LOL,
DonW