I got a few questions. A few months back i replaced my thermostat with one of those fail safe ones from orielly's. Well it's been working fine but not it seems like after i start it, it will get to operating temp and then when the thermostat opens it will cool off and stay cool. Do you all think that it's just sticking open until it cools completely off the next time i start it up or what?

Also it was idling a little rough so i changed my spark plugs and cleaned my egr valve, after that it seemed to help out some. That was about two weeks ago and now when I'm parked and it's idling it seems to idle kind of rough again, do you all know what else it might be or what i could check. Also i've ran seafoam through it before i changed the plugs and i've been running injector cleaner through it a couple weeks ago.

 

Did you clean the intake manifold passages when you had the EGR valve off for cleaning? If not then your EGR might be carbon fouled agian...get a good sensor safe carbon cleaner for the EGR and also spray the inside till it is full, let it set while you go to clean out the manifold passages for the EGR supply. One method is to leave the EGR valve off and start the engine and let the exhaust supply "blow out" the carbon make sure that nobody stands in front of the truck or they will look like a chimney sweep with black carbon...then just put everything back together.

 

Yeah i cleaned the intake manifolds and the egr valve with seafoam. I didn't start it up before i put it back on though. I didn't know if that would hurt it or not.

 

Did you ever get the answer? I have the same problem here in Toronto with my 1996 LT, it seems to run about 50 degrees F lower than it should and eat gas like crazy. Its been in the shop many times trying to fix the heater (replaced everything that water flows thru and had the heads apart to clean out the intakes). A friend with a 4.3 VORTEC in his boat says the cooling water in his boat was bypassing around the thermostat so it never got to operating temperature, he got an extra o-ring/gasket and it solved the problem by getting a better seal around the t-stat. My LT runs marginally hotter now that the warmer weather is here. I'd sure love to know what it is.

 

Sounds like a stuck open thermostat...if the temperature does not go above 175* then the computer thinks that the engine needs more fuel because the engine operating temperature has not been reached (175*), if the engine reaches operating temp then the computer goes into normal operating mode...

 

If the engine doesn't hit running temperature, then the fuel doesn't burn right, either, so you get less mileage and power...

My old S10 could squawk the tires going into second... But only on a really hot day, after being driven hard for a long time... it needed a new t-stat....


Make sure that your t-stat is in the right way...