Thermostat: Service and Repair

Engine Coolant Thermostat Replacement (4.3L)

Removal Procedure




1. Remove the air cleaner and the duct assembly. Refer to Air Cleaner Outlet Resonator Replacement (Service and Repair).
2. Partially drain the coolant. Refer to Cooling System Draining and Filling (Static Fill) (Service and Repair)Cooling System Draining and Filling (Vac N Fill) (Service and Repair).
3. Remove the coolant recovery reservoir. Refer to Coolant Recovery Reservoir Replacement (Service and Repair).
4. Disconnect the radiator hose from the thermostat housing.




5. Remove the bolts attaching the thermostat housing to the thermostat.
6. Remove the thermostat housing.
7. Remove the thermostat.
8. Clean the gasket mating surfaces.

Installation Procedure

Caution: Refer to Coolant Addition Notice.




1. Install the thermostat.
2. Install the thermostat housing to the intake manifold.

Caution: Refer to Fastener Caution (Fastener Caution).

3. Install the bolts to the housing and tighten to 25 Nm (18 lb ft).




4. Connect the radiator hose to the thermostat housing.
5. Install the coolant recovery reservoir. Refer to Coolant Recovery Reservoir Replacement (Service and Repair).
6. Install the air cleaner and the duct. Refer to Air Cleaner Outlet Resonator Replacement (Service and Repair).
7. Refill the cooling system. Refer to Cooling System Draining and Filling (Static Fill) (Service and Repair)Cooling System Draining and Filling (Vac N Fill) (Service and Repair).
8. Bleed the air from the cooling system.
9. Inspect the thermostat housing and the gasket for coolant leaks.