How to Replace a Thermostat in a Saturn SL1

by Gregory Crews
temperature dial image by Robert Kelly from

The Saturn SL1 is a fuel-efficient car produced by General Motors. The high revolution engine in this car makes the coolant system a crucial part of the vehicle. The coolant system is controlled by a thermostat, which is set to open once the engine gets hot. At this point, the thermostat will release enough coolant to flow through the engine and cool it down. Once the thermostat starts to stick, it will need to be replaced. Draining the radiator will be required to prevent spilling the coolant during the replacement process.

Draining the Radiator

Step 1

Open the hood to access the coolant system. Twist the coolant reservoir cap off counterclockwise. Remove it and set it aside.

Step 2

Set the parking brake to prevent the car from rolling backwards when raised. Chock the back wheels.

Step 3

Place a jack under the front cross-member. Raise the front of the car high enough to place jack stands under the pinch points located under the front doors. Lower the car onto the jack stands.

Step 4

Unbolt the splash guard at the bottom of the car with a socket wrench.

Step 5

Place a drain pan under the radiator. Locate the drain plug at the bottom of the radiator on the passenger side. Turn the drain plug counterclockwise with a pair of pliers and drain the coolant. Tighten the plug back onto the radiator once the coolant has drained. Pull the drain pan out from under the car.

Step 6

Tighten the splash guard back onto the bottom of the car with the socket wrench. Do not over-tighten the bolts as they are made of a hard plastic and could strip out.

Raise the car up and remove the jack stands. Lower the car to the ground with the jack.

Replacing the Thermostat

Step 1

Locate the thermostat by tracing the lower radiator hose to the engine. This can be reached easier from the top of the engine compartment.

Step 2

Unscrew the two bolts at the end of the radiator hose with a socket wrench. Pull the hose and the thermostat away from the engine.

Step 3

Loosen the hose from the thermostat housing with a flat head screwdriver. Pull the thermostat housing out of the hose.

Step 4

Place the new thermostat and housing into the hose. Tighten the hose clamp to secure it in place.

Step 5

Apply RTV silicone around the ridge in the housing. Place a new O-ring onto the silicone. The silicone will hold the O-ring in place for mounting the thermostat housing.

Step 6

Push the housing back together. Screw the two bolts into the bolt holes to secure the housing. Tighten the bolts with the socket wrench.

Step 7

Pour pre-mixed coolant into the reservoir.

Step 8

Start the car and let it idle. Once the car warms up, pour coolant into the reservoir until the level is full. Tighten the cap onto the reservoir.

Close the hood and turn off the car.


  • Replacement thermostats are available at most auto parts stores.


  • Contact a local recycling center for disposal of the old coolant. Coolant is hazardous to children and small animals if ingested.

Items you will need

  • Jack
  • Jack stands
  • Pliers
  • Drain pan
  • Socket set
  • Socket wrench
  • Replacement thermostat
  • Replacement O-ring
  • 2 gallons of coolant
  • RTV silicone

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