Thermostat: Service and Repair

Thermostat Replacement (4.3L Engine)

Removal Procedure





1. Drain the cooling system. Refer to Draining and Filling Cooling System (Static Fill) Draining and Filling Cooling System (w/RPO HP2) Draining and Filling Cooling System (Vac-N-Fill).
2. Loosen the air cleaner outlet duct clamp at the mass airflow/intake air temperature (MAF/IAT) sensor.





3. Remove the positive crankcase ventilation (PCV) hose.





4. Remove the air cleaner adapter nut.





5. In order to remove the air cleaner outlet duct, pivot the duct upward until the hinge clip releases from the lip on the throttle body.





6. Reposition the inlet hose clamp at the water outlet.
7. Remove the inlet hose from the water outlet.





8. Remove the water outlet studs.





9. Remove the water outlet.





10. Remove the thermostat.
11. Clean the sealing surface of the water outlet.
12. Clean the sealing surface of the intake manifold.
13. Remove and discard the O-ring seal.

Installation Procedure





1. Install a NEW O-ring seal to the thermostat.
2. Install the thermostat.





3. Install the water outlet.





4. Notice: Refer to Fastener Notice in Service Precautions.

Install the water outlet studs.
Tighten the studs to 25 Nm (18 ft. lbs.).





5. Install the inlet hose to the water outlet.
6. Position the inlet hose clamp at the water outlet.





7. Align the hinge clip with the lip on the throttle body. In order to install the air cleaner outlet duct, pivot the air cleaner outlet duct downward until the mounting stud is through the hole.





8. Install the air cleaner adapter nut.





9. Install the PCV hose.





10. Tighten the air cleaner outlet duct clamp at the MAF/IAT sensor.
Tighten the clamps to 4 Nm (35 inch lbs.).
11. Fill the cooling system. Refer to Draining and Filling Cooling System (Static Fill) Draining and Filling Cooling System (w/RPO HP2) Draining and Filling Cooling System (Vac-N-Fill).
12. Inspect the cooling system for leaks.