Thermostat: Service and Repair

Thermostat Replacement (6.6L (LLY, LBZ))

Removal Procedure

1. Remove the upper fan shroud.
2. Remove the intake manifold.
3. Drain the cooling system.




4. Compress the clamp and disconnect the radiator inlet hose from the thermostat housing.




5. Remove the fuel line bracket bolt and position the fuel line aside.




6. Compress the clamp and disconnect the turbocharger cooling inlet pipe from the thermostat housing.




7. Remove the 4 bolts and the thermostat housing.
8. Remove the thermostat and seals.

Inspection Procedure

1. Inspect the thermostats for sticking, cracks, and/or leakage of wax.
2. Replace the thermostats if damage is found.
3. Clean the thermostat housing and thermostat housing cover sealing surfaces.

Installation Procedure




1. Install the thermostats and seals to the thermostat housing.
The rear thermostat (4) has 2 vent valves. Install the vent valves towards the rear of the engine.





Notice: Refer to Fastener Notice.

2. Position the thermostat housing and install the 4 bolts.

Tighten the thermostat housing bolt to 21 N.m (15 lb ft).




3. Compress the clamp and connect the turbocharger cooling inlet pipe to the thermostat housing.




4. Position the fuel line to the thermostat housing and install the fuel line bracket bolt.

Tighten the fuel line bracket bolt to 21 N.m (15 lb ft).




5. Compress the clamp and connect the radiator inlet hose to the thermostat housing.
6. Install the intake manifold tube.
7. Install the upper fan shroud.
8. Fill the cooling system.