How to Install a Thermostat in a 2002 Chevy Trailblazer

The 2002 Chevy Trailblazer is powered by a 4.2-liter in-line six-cylinder engine and an automatic transmission. The thermostat on the 4.2-liter is responsible for allowing coolant to pass through the cooling system when the engine reaches 195 degrees F. The thermostat is located on the left side of the engine just below the intake manifold. To replace the thermostat, some coolant must be drained and replaced.

Instructions

Removal

1

Park the Trailblazer on a level surface. Lift the vehicle hood and secure it with the hood prop rod. Allow the engine to completely cool and remove the radiator cap.

2

Place the drain pan under the right corner of the radiator, directly under the radiator drain cock. Install the 1/4-inch ratchet into the hole on the drain cock. Rotate the drain cock counterclockwise until coolant begins to pour from the radiator drain spout. Allow about two gallons of coolant to drain and close the drain cock.

3

Remove the drain pan and store the used coolant in a safe place until it can be disposed of properly.

4

Follow the lower radiator hose until it meets the thermostat housing. Squeeze the pressure clamp with the pliers, and slide the clamp up the hose. Remove the lower radiator hose from the thermostat housing.

5

Remove both thermostat housing mounting bolts with the socket and ratchet. Remove the thermostat housing and thermostat from the engine.

6

Clean the mating surface on the engine and the thermostat housing with the wire brush.

Installation

7

Inspect the new thermostat to ensure the rubber gasket is installed. Place the new thermostat into the thermostat housing. Install the thermostat housing and thermostat to the engine. Tighten the thermostat mounting bolts to 89 inch-pounds with the torque wrench.

8

Slide the lower radiator hose onto the thermostat housing. Squeeze the pressure clamp with the pliers and slide the clamp down the hose. Release the pressure clamp to secure the lower radiator hose to the thermostat housing.

9

Fill the radiator with fresh 50-50 DEXCOOL coolant. Start the engine and allow it to reach operating temperature. Continue to add fresh coolant to the radiator as the engine warms up. Increase the speed of the engine to 2,500 rpm and hold it for two minutes. Shut the engine off.

10

Top off the radiator and coolant overflow tank with the fresh DEXCOOL coolant. Install the radiator cap.

11

Pour the used coolant into the empty DEXCOOL jugs and take them to a local shop or parts store to have them disposed of properly.