Engine Coolant Thermostat Replacement L21/LP4

1. Remove the front left wheelhouse panel.



2. Remove the front intake air duct (1) from the air filter housing.
3. Drain the coolant. Refer to Cooling System Draining and Filling .
4. Remove the upper radiator hose from the coolant outlet.
5. Remove the coolant outlet bolts.



6. Remove the coolant outlet and the thermostat.
7. Remove the coolant outlet gasket.
8. Clean the following components:

•	The surface of the intake manifold

•	The coolant outlet

9. Inspect the manifold and the coolant outlet mating surfaces for the following conditions:

•

Pits

•

Cracks

•	Other damage that could cause leaking

1. Install the thermostat.
2. Install the gasket.
3. Install the coolant outlet.

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.

4. Install the coolant outlet bolts.

Tighten
Tighten the coolant outlet bolts to 37 N·m (27 lb ft).

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



6. Install the front intake air duct (1) to the air filter housing.
7. Install the front left wheelhouse panel.
8. Fill the cooling system. Refer to Cooling System Draining and Filling .
9. Inspect the system for leaks.

Engine Coolant Thermostat Replacement LG5

Refer to the Caterpillar® 3126 Unit Repair Manual for information on replacement of the diesel engine thermostat.

1. Remove the front wheelhouse panel.



2. Remove the front intake air duct (1) from the air filter housing.
3. Drain the coolant. Refer to Cooling System Draining and Filling .
4. Remove the upper radiator hose from the coolant outlet.
5. Remove the coolant outlet bolts.



6. Remove the coolant outlet.
7. Remove the thermostat(s) (1).
8. Remove the coolant outlet gasket.
9. Clean the following components:

•	The surface of the coolant crossover manifold (2)

•	The coolant outlet

10. Inspect the coolant crossover manifold and the coolant outlet mating surfaces for the following conditions:

•

Pits

•

Cracks

•	Other damage that could cause leaks

1. Install the thermostat(s) (1).
2. Install the gasket.
3. Install the coolant outlet.

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.

4. Install the coolant outlet bolts.

Tighten
Tighten the coolant outlet bolts to 42 N·m (31 lb ft).

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



6. Install the front intake air duct (1) to the air filter housing.
7. Install the front wheelhouse panel.
8. Fill the cooling system. Refer to Cooling System Draining and Filling .
9. Inspect the system for leaks.