RUNS HOT, THEN OK, NOW HOT AGAIN?

[sandyrdsp]

I bought a '95 SLS. First day the heater coil blows. Had it replaced, and it had an idle problem so replaced the idle motor as well. Then the mechanic said he took it out and it ran hot. Thought the head gasket was gone and suggested to tow it to a dealer. Instead I drove it to the dealer and it did not get hot(10-11 mi.) They suggested to drive it until it does then tow it. It might have been a stuck thermos. So. drove it home...around town. The Next day, the same but then it overheated that afternoon. Had thermostat taken out. Took it home, no problem (7-9 mi). Thought I would take it on the interstate and see, took it up to 85-90 mph. Hot again. Also the info center rotates between trunk open to traction disabled, when it does not give engine coolant hot, etc. Any ideas. I saw one post from someone about the EGR vavle doing something similar.

[PAUL T]

Is it possible that they did not fill the radiator with the correct amount or concentration of anti-freeze or that an air bubble developed and caused it to overheat. Did they add the supplemental pellets? Is there in antifreeze in the oil? Are there any codes showing? The Northstar is designed to go up to 50 miles with no antifreeze in "limp mode" so why tow it. If I remember right there is a line that goes from the water pump to the surge tank, if it is pinched or clogged it can cause overheating. If it get too hot a message will come up on the info center if the sensor is working.

[KevinW]

The cooling system will not function correctly without a thermostat in place.

Look for gas bubbles in the surge tank after a cold start.