How to Change the Thermostat on a '99 Intrigue

by Lisa Wampler

One of the most overlooked systems in an automobile is the cooling system. We're accustomed to changing the oil every 3,000 miles, but rarely is the radiator flushed out. Sludge can build up in the cooling system and collect around the mechanical thermostat. This in turn can cause the thermostat to fail and major engine issues to ensue. If you've neglected the cooling system in your 1999 Oldsmobile Intrigue, it's time to replace the thermostat.

Take the radiator hose off the thermostat cover by loosening the nut that holds the band clamp around the hose. With the hose loosened, pull the radiator hose off the thermostat cover.

Loosen the cover by removing the bolts that hold it onto the top of the engine with an adjustable wrench. Remove the cover from the engine.

Pull the thermostat out of the engine and discard it. Scrape the old paper gasket off the engine with a small scraper. To prevent getting any gasket into the engine, plug the hole that the thermostat was in with a shop towel. Once the gasket has been scraped off the engine, remove the shop towel from the hole.

Place a new thermostat into the engine with the correct side up. (The thermostat will be stamped with the word "up" or "top"--this end should stick out of the engine.)

Place RTV silicone gasket maker onto the mating surface of the engine. (Due to the Intrigue's age, the use of RTV silicone gasket maker is preferred over a paper gasket to prevent leaks due to imperfections in the mating surfaces of the engine and the thermostat cover.)

Bolt the cover back into place using the original bolts that were removed. (The RTV silicone gasket maker will squeeze out; this is normal.) Place the radiator hose back onto the cover and tighten it into place.


  • Do not change the thermostat with the Intrigue warmed up. Radiator fluid can reach 200 degrees and can burn if it touches skin.

Items you will need

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  • radiator humor image by John Sfondilias from Fotolia.com