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How to Replace the Thermostat on a 3800 Engine

by Gregory Crews

The 3800 engine was made for General Motors and used in their sedans. Buick, Chevrolet, Oldsmobile and Pontiac all relied on this engine for power and efficiency. The coolant system relied on the thermostat the the way the care cars relied on the engine for maximum performance. The car will overheat and can cause serious engine trouble when the thermostat fails.

Open the hood for access to the engine compartment. Locate the top radiator hose and trace it to the engine.

Unscrew the hose clamp securing the hose to the thermostat-housing inlet pipe with a slotted screwdriver. Pull the pipe away from the pipe.

Unbolt the screws holding the thermostat cover in place with a socket wrench. Pull the housing cover off by hand. Pull the old thermostat out of the assembly by hand.

Insert the new thermostat with the spring side in first. The thermostat can just be dropped in the housing.

Scrape the gasket material off the mating surfaces of the housing with a razor scraper. Ensure all the black gasket material is removed before applying the new gasket.

Apply the new gasket on the mating surface of the thermostat cover. Ensure the bolts holes match up.

Bolt the cover back on to the housing with a socket wrench. Ensure the bolts are tight to create a seal for the gasket.

Slide the hose back over the inlet pipe. Tighten the hose clamp with a slotted screwdriver.

Twist the radiator cap counterclockwise to pull off the radiator. Fill with pre-mixed coolant until the radiator cannot hold any more.

Start the car and allow it to idle. When the vehicle warms up, the level will drop. Fill with more coolant until the radiator cannot hold any more.

Turn the car off. Tighten the cap back on to the radiator. Close the hood.

Tip

  • Purchase the thermostat and the gasket as a kit.

Warning

  • Use caution working around coolant as the system is under pressure and very hot.

Items you will need

About the Author

Gregory Crews has been in the film industry for three years and has appeared in more than 38 major motion pictures and 16 television shows. He also writes detailed automotive tutorials. His expertise in the automotive industry has given him the skills to write detailed technical instructional articles.

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