thermostat is stuck closed

Asked by GuruKKHKW Dec 13, 2019 at 12:04 AM about the 1998 Cadillac DeVille

Question type: Maintenance & Repair

Overheating and still coolant in resivor. Do I have to
change the waterpump

2 Answers


If you know your thermostat is stuck closed wouldn't you first change it out and see what happens? The water pump provides the circulation of the coolant through the engine, heater and radiator. If it was bad you would see no obvious flow in the radiator neck but, the thermostat would need to be open.

1 people found this helpful.

Before putting a lot of money in this vehicle have the coolant tested for combustion gases. Northstar engines are notorious for blowing head gaskets and if you have combustion gases in the coolant you have a blown head gasket and the vehicle is not worth fixing. Hope that helps! Jim

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