Engine Coolant Thermostat Replacement Caterpillar

Refer to the Caterpillar® Service Manual.

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).

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

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 .

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

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

1. Install the thermostats.



2. Install the coolant outlet (1).

Notice: Refer to Fastener Notice 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 6.6L LLY

1. Remove the air cleaner . Refer to Air Cleaner Replacement for the 6.6L (LLY) engine.
2. Remove the charged air cooler pipes. Refer to Charged Air Cooler Hoses/Pipes Replacement .



3. Remove the water outlet. Refer to Water Outlet Tube Replacement .
4. Remove the bolt for the fuel line bracket.
5. Remove the thermostat housing cover bolts.
6. 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.

Notice: Refer to Fastener Notice in the Preface section.




2. Install the thermostat housing cover.
3. Install the thermostat housing cover bolts.

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

4. Install the fuel line bracket bolt.

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

5. Install the water outlet. Refer to Water Outlet Tube Replacement .
6. Install the charged air cooler pipes. Refer to Charged Air Cooler Hoses/Pipes Replacement .
7. Install the air cleaner . Refer to Air Cleaner Replacement for the 6.6L (LLY) engine.