How to Replace a Thermostat on a 2001 Pontiac Sunfire

by Gregory Crews
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temperature dial image by Robert Kelly from

The 2001 Pontiac Sunfire relies on the thermostat to regulate the engine temperature. The Sunfire is a compact, fuel-efficient car that relies on a properly running coolant system for optimal performance. The thermostat will show signs of failure when the temperature gauge is indicating a hot engine. Replacing the thermostat will take a few minutes. The end result is a cool-running, dependable vehicle.

Step 1

Pop the hood release to access the thermostat housing. Locate the top hose on the radiator. Trace it to the engine.

Step 2

Unbolt the hose clamp holding the hose to the thermostat housing with a flat screwdriver. Pull the hose off the housing by hand.

Step 3

Unbolt the two bolts holding the thermostat housing together with a socket wrench. Pull the cover off the thermostat housing.

Step 4

Pull the thermostat out of the assembly by hand. Discard the old thermostat.

Step 5

Scrape the black gasket material around both surfaces with a razor scraper. Ensure both surfaces are clean.

Step 6

Deposit the new thermostat into the housing with the spring end down. The thermostat will rest inside the housing.

Step 7

Position the new gasket around the bottom surface of the housing. Ensure the bolt holes on the gasket match up with the bolt holes on the surface.

Step 8

Bolt the surfaces together with a socket wrench. Ensure the surfaces are bolted tight to prevent leaking of coolant.

Step 9

Slide the hose over the inlet pipe. Slide the hose clamp over the hose and the pipe. Tighten the hose clamp with a flat screwdriver.

Step 10

Twist the radiator cap off to fill the radiator with coolant. Pour in pre-mixed coolant into the radiator until it is full.

Step 11

Start the car and allow it to warm up. Once the car is warm, the level of coolant will drop. Fill the radiator with additional coolant until it can not hold any more coolant.

Step 12

Tighten the radiator cap back onto the radiator. Close the hood and turn the car off.

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