Thermostat: Service and Repair

THERMOSTAT INLET HOUSING AND ELEMENT

IMPORTANT: During extremely cold weather, -12° C (10° F) 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. Disconnect radiator hose at thermostat housing. Use Snap-on Tool HCP10 or 20 (or equivalent) to remove hose clamp.





3. Remove thermostat housing bolts.
4. Remove thermostat housing and thermostat element.
5. Discard O-ring.

NOTICE: The thermostat will not function correctly once it is contacted by oil. If oil is found in the cooling system, it must be flushed and the thermostat's cartridge replaced.

6. Inspect the thermostat components for damage, seat deterioration, etc.

INSPECTION

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





1. In order to check if the thermostat valve is opening properly, perform the following test:
1.1. Completely submerge the thermostat in the glycol solution. The solution should be 11° C (22° F) above the temperature indicated on the thermostat valve.
1.2. Thoroughly agitate the solution. Under these conditions, the thermostat valve should open.
2. In order to check if the thermostat valve is closing properly, perform the following test:
2.1. Completely submerge the thermostat in the glycol solution. The solution should be 6° C (10° F) below the temperature indicated on the thermostat valve.
2.2. Thoroughly agitate the solution. Under these conditions, the thermostat valve should close completely.

INSTALLATION





1. Install a new O-ring on the inlet housing:
1.1. Install thermostat and inlet housing into thermostat inlet housing.
1.2. Install retaining bolts.
Torque:
Thermostat Housing-to-Block Bolts: 10 Nm (89 inch lbs.)
1.3. Close radiator drain plug.

IMPORTANT: The vehicle must be level when filling with coolant.





2. Fill the cooling system to the FULL COLD line with coolant. Use a 50/50 mixture of DEX-COOL(R) antifreeze and clean water.
3. Run engine until upper radiator hose is hot, then add additional coolant, if needed, to bring the level to the FULL COLD line.
4. Install pressure cap and check for leaks.