Hey guys, My 00 4.7 sport is overcooling , the coolant temp gauge will not even get close to around 195. I replaced the thermostat last winter for the same kind of problem, however I used a O'reilly Murray T-stat . I dont think this T-stat is a correct design so I bought a Stant one which is similar to OEM. So my question is this should be the Thermostat doing this right? and on a side note I am getting pretty bad mileage like 9mpg's around time.Ya'll think putting in this Stant T-stat should solve the overcooling and mpg problem im having? Thanks guys. Thax

 

Use only a factory stat and most importantly, properly follow the burping procedures.

IndyD

 

Indy so you think a Stant T-stat isnt up to the task?

 

Basically, as for the mpgs sound like you need some pre-cat O2 sensors.

 

correct, you need a OEM style stat with the weep hole in it for the 4.7, i have not seen them anywhere except at the dealer.

now this may fix your bad mpg problem too because when the engine is cold the computer dumps fuel into it (open loop operation) in order to warm the engine up faster, once it is warmed up the computer starts listening to the O2 sensors (closed loop operation) to control the a/f mixture, if your not getting the truck warm enough to enter closed loop operation that will lower your mpgs ALOT, it is also part of the reason you get such bad mpgs in the winter as compared to the summer, (well that and winter blend gas)

 

+1 to your +1 for me SS.

The stocker has the weep hole that most aftermarkets don't or don't do right. 4.7s should always use the stocker stat and call it a day after a proper burp.

Also +1 on SSs comment that the system could be in a cold loop costing you gas and mileage.

IndyD

 

+1, +2, whatever.....

Well if the motor is running cold it would keep you in open loop and hinder your fuel milage, so yes it could be doing it. However a different issue could be an pre-cat O2 sensor. First things first, fix the temp issue.

Now go to the dealer and get a new T-stat as that is the only sure fire way and the best that works for the 4.7L engine. Burp it real good! Then move on after that.

Finally, it could be a bad temp sensor. Use an infared or other thermometer and test the water coming out of you engine to see what the actual temp is.

 

Ok so I decided not to replace the T-Stat as I realized my commute to work is real short like 2.5 miles so probably wouldnt get up to temp in that time anyway and havent had a problem really when I do get it on the highway. Now my mileage wasnt as bad as I thought it was , I just filled up and it was 11.5mpg for the whole tank doing very short trips. Hydra I was thinking what you were saying about the temp sensor , could be bad ill take a voltmeter to it and get a infared on the coolant . Thanks guys for the tips. Thax