running cool after coolant change

[signalnc]

My 2003 has been running cooler than normal since I got the coolant changed. I have no scan tool. The dash says it's running around 160 and my gas mileage is really bad, so not that the dash is exact, but I obviously have an issue. Could it be the ECT? I was thinking it is just the thermostat.

just as a side not I did tell the shop to change the thermostat when I had the coolant done and they didn't do it. I guess the trails of emails back and forth it was missed.

 

[Mooseman]

Could be thermostat (likely) or the temp. sensor. Not just your mileage can be bad but it can also kill your cat because it is running rich. Get both the stat and sensor changed at the same time since both are close to each other. Do it ASAP.

 

[signalnc]

done-running at 210 now

 

[Mooseman]

 

[seanpooh]

I don't know why but it seems when we do a coolant flush the thermostat "suddenly" goes bad.

 

[CaptainXL]

There really is no such thing as a "flush" with the 4.2 I6 engines. In order to drain all the coolant the thermostat housing needs to come off because it blocks the coolant from coming out the lowest point of the block. At this point you might as well replace the thermostat since it's off.