Thermostat: Service and Repair

THERMOSTAT INLET HOUSING AND ELEMENT

IMPORTANT: During extremely cold weather, 10° F (-12° C) or colder, your engine's coolant temperature will decrease quickly when idling with the heater fan on high speed and cool air may flow from the heater outlets. The fan control switch can be set at a slower speed position (fan speed I or II) to maintain the hottest air flow.

REMOVAL





1. Drain coolant.
2. Remove intake plenum.
3. Remove intake manifold.





4. Remove radiator hose from inlet housing.

NOTICE: It may be necessary to lift engine with floor jack to allow extension housing to be removed over radiator.

5. Remove thermostat extension housing bolt and extension housing.
6. Remove and discard O-ring seals.





7. Remove thermostat with housing:
^ Remove bolts.
^ Tilt the rear of the thermostat housing upward.
^ Lift out the housing.
^ Remove and discard O-ring seal.

THERMOSTAT INSPECTION

NOTICE: Use extreme care and do not damage or scratch the machined aluminum surfaces. Coolant leaks will result.





1. Check the valve opening temperature. Suspend the thermostat in a pan of water. Gradually heat the water until the thermostat begins to open. Check the water temperature immediately after the thermostat opens. Replace the thermostat if it does not open within specifications.
Starts to open temperature:
New: 84-88° C (182-190° F)
Used: 83-89° C (180-192° F)
2. Inspect thermostat sealing surfaces for leaks.

THERMOSTAT INLET HOUSING AND ELEMENT

INSTALLATION





1. Install the thermostat with housing:
^ Install a new O-ring seal.
^ Position the thermostat with the housing.
^ Install the housing bolts.
Torque:
Thermostat Housing Bolts: 20 Nm (15 ft. lbs.)





2. Lubricate the extension housing O-rings with coolant.
3. Install O-rings on extension housing.

NOTICE: It may be necessary to lift engine with floor jack to allow extension housing to be installed over radiator.





4. Install extension housing on thermostat housing.
5. Install extension housing bolt.
Torque:
Thermostat Housing Bolts: 20 Nm (15 ft. lbs.)





6. Install the radiator hose to thermostat extension pipe.
7. Install intake manifold.
8. Install intake plenum.
9. Fill the cooling system.