Cadillac Repair: 1998 cadillac seville sts, 1998 cadillac seville, cadillac seville

Question
My Cadillac overheated without any warning, brought it home,I replaced the water pump, thermostat, coolant tempature sensor,fan relay fuse, and the radiator.. my car takes about 20 minutes to overheat now in idle... and about 15 minutes when I test drive it down the road. I went and rented a tool from Autozone to check if my head gaskets are leaking, the tool you insert into the coolant resovior and add this blue die, and if it changes colors (yellow) it means you have a bad head gasket,but it didnt change colors... I checked the oil and not milky, car runs great, power still up to normal, no white smoke out of the exhaust. I am baffled,don't know what to do now. PLEASE I NEED SOME HELP!!   THANKS FOR YOUR TIME.   R. SANCHEZ

Answer
Hello,

If you read my archives you will see I was addressing overheating on these engines twice a weak. Bottom line--if you drive this aluminum engine hot, you will have major mechanical problems.

Not sure what this autozone test is, but there are better ways to test it like using a pressure tester in the radiator and seeing if the pressure changes by different revolutions of the engine.

These Cadillacs are a great car until an overheating problem presents itself. There are so many causes I can't even name the problems. Rust in the water jackets or cooling system itself will present problems. Radiator fan not functioning. As for a head gasket test, there is not any absolute determination on these unless the heads are torn off. Sometimes they blow white smoke, and you say yours doesn't. Some times the crank case will fill up with coolant turning the oil white. Sometimes the heads are warped from over heating and have to be milled. Sometimes the block will crack. There are far too many variables here for me to give you an absolute answer.

Although we like to save money and fix the car ourselves, sometimes in the long run, its cheaper to go to a good service garage and you don't need to be raped by the dealer.

I have always said I love Cadillacs, I have owned over 25. Once the engine is driven hot, major problems can develop and the only way to properly diagnose the problem is with an experienced technician being at the vehicle.