Coolant Heater Replacement 6.6L (LLY) Engine

1. Drain the cooling system. Refer to Cooling System Draining and Filling.
2. Disconnect the engine coolant heater cord.
3. Remove the ground wire from engine block.



4. Loosen the coolant heater bolt.
5. Remove the engine coolant heater from the engine block.
6. Do not score the machined surface of the hole.
7. Grasp the plug with pliers.
8. Pull the plug from the engine block.
9. Clean the core plug hole in order to remove the following substances:

•

Burrs

•

Compound

•

Paint

•	Rough spots

1. Coat the O-ring seal and the cleaned surface of the plug opening with water resistant high-temperature grease lubricant GM P/N 1052196 (Canadian P/N 5264008), or the equivalent.

Note: Avoid element contact with the inside walls of the engine block.

2. Align the coolant heater element to point towards the top of the engine.
3. Tightly push the coolant heater into the engine block.

Caution: Refer to Fastener Caution in the Preface section.




4. Tighten the bolt on the engine coolant heater until both of the locking wings draw tightly against the inner wall of the engine block.

Tighten
Tighten the bolt to 2 N·m (18 lb in).





Notice: The heater cord must not touch the engine, hot pipes, manifold, or any moving parts. Route the cord to the left front of the engine compartment securing with tie straps as necessary to prevent damage.

5. Connect the heater cord to the coolant heater.
6. Install the ground wire to engine block.
7. Fill the cooling system. Refer to Cooling System Draining and Filling.
8. Inspect for coolant leaks.

Coolant Heater Replacement LG5

1. Drain the coolant. Refer to Cooling System Draining and Filling.
2. Remove the heat shield, if equipped.
3. Disconnect the electrical cord connector from the engine coolant heater.
4. Loosen the center screw to the limit of the thread.



5. Remove the engine coolant heater from the engine block.
6. Inspect the hole in the block for smoothness. Remove any burrs or rough spots.

Warning: A block heater electrical cord that is damaged creates a shock hazard, and must be replaced.

7. Inspect the electrical cord and the cord ends for corrosion or damage.
8. Clean the hole in the block.
9. Clean the electrical connectors.

1. Apply a coat of petroleum jelly to the following components:

•	The opening of the heater

•	The rubber O-ring seal




2. Insert the engine coolant heater into the hole in the engine block.
3. Position the hairpin end of the engine coolant heater straight up.

Caution: Refer to Fastener Caution in the Preface section.

4. Tighten the engine coolant heater center screw.

Tighten
Tighten the engine coolant heater center screw to 3 N·m (23 lb in).

5. Install the heat shield, if equipped.

Tighten
Tighten the heat shield bolt to 12 N·m (106 lb in).

Note: Route the electrical cord so that the cord does not touch the engine, the exhaust manifold or any moving parts. Leave slack between the engine and the frame so that engine vibration will not stretch the cord or damage the connection at the heater.

6. Connect the electrical cord connector to the engine coolant heater.
7. Fill the cooling system. Refer to Cooling System Draining and Filling.
8. Inspect the system for leaks.

Coolant Heater Replacement L18

1. Drain the cooling system. Refer to Cooling System Draining and Filling.
2. Disconnect the heater cord from the coolant heater.
3. Remove the engine coolant heater from the engine block.

1. Coat the O-ring seal and the cleaned surface of the plug opening with water resistant high-temperature grease lubricant GM P/N 12346004 (Canadian P/N 10953480) or the equivalent.

Caution: Refer to Fastener Caution in the Preface section.

2. Install the coolant heater.

Tighten
Tighten the engine coolant heater to 50 N·m (40 lb ft).

3. Connect the heater cord to the coolant heater.
4. Fill the cooling system. Refer to Cooling System Draining and Filling.