Engine Coolant Thermostat Replacement Caterpillar

Refer to the Caterpillar® Service Manual.

Engine Coolant Thermostat Replacement 6.6L LMM

1. Remove the air cleaner. Refer to Air Cleaner Assembly Replacement.
2. Remove the water outlet. Refer to Water Outlet Tube Replacement.
3. Remove the cooling fan shroud top bracket bolts.



4. Remove the thermostat housing cover bolts.
5. Remove the thermostats and seals.

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

1. Install the thermostats and seals to the thermostat housing.

The rear thermostat (4) has 2 vent valves. Install with the vent valves towards the rear of engine.




2. Install the thermostat housing cover.

Caution: Refer to Fastener Caution in the Preface section.

3. Install the thermostat housing cover bolts.

Tighten
Tighten the bolts to 21 N·m (15 lb ft).




4. Install the cooling fan shroud top bracket bolts.

Tighten
Tighten the bolts to 21 N·m (15 lb ft).

5. Install the water outlet. Refer to Water Outlet Tube Replacement.
6. Install the air cleaner. Refer to Air Cleaner Assembly Replacement.

Engine Coolant Thermostat Replacement LG4

1. Drain the coolant. Refer to Cooling System Draining and Filling.
2. Remove the upper radiator hose from the coolant outlet.



3. Remove the coolant outlet bolts.
4. Remove the coolant outlet (1).
5. Remove the thermostats (2).
6. Clean the following surfaces:

•	The inlet manifold

•	The coolant outlet

7. Inspect the coolant outlet for the following conditions:

•	Flat mating surfaces

•

Pits

•

Cracks

•	Other damage

Note: Place the thermostat with the jiggle valves on the left side.

1. Install the thermostats.



2. Install the coolant outlet (1).

Caution: Refer to Fastener Caution in the Preface section.

3. Install the coolant outlet bolts.

Tighten
Tighten the coolant outlet bolts to 19 N·m (14 lb ft).

4. Install the upper radiator hose to the coolant outlet.

Tighten
Tighten the clamp to 5 N·m (44 lb in).

5. Fill the cooling system. Refer to Cooling System Draining and Filling.
6. Inspect the system for leaks.

Engine Coolant Thermostat Replacement 8.1L Engine

1. Drain the cooling system. Refer to Cooling System Draining and Filling.
2. Reposition the inlet hose clamp at the water outlet.
3. Remove the inlet hose from the water outlet.



4. Remove the water outlet bolts (2).
5. Remove the water outlet (1).
6. Remove the thermostat (3).

1. Install the thermostat (3).
2. Install the water outlet (1).

Caution: Refer to Fastener Caution in the Preface section.

3. Install the water outlet bolts (2).

Tighten
Tighten the bolts to 30 N·m (22 lb ft).




4. Install the inlet hose to the water outlet.
5. Position the inlet hose clamp at the water outlet.
6. Fill the cooling system. Refer to Cooling System Draining and Filling.