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Coolant Heater Replacement 4.3L

Removal Procedure

    Object Number: 312949 Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling .
  2. Disconnect the heater cord from the coolant heater (4).
  3. Loosen the coolant heater bolt.
  4. Remove the coolant heater from the engine block.
  5. Do not score the machined surface of the hole.
  6. Grasp the plug with pliers.
  7. Pull the plug from the engine block.
  8. Clean the core plug hole in order to remove the following substances:
    9. • Burrs
    • Compound
    • Paint
    • Rough spots

Installation Procedure

    Object Number: 312935 Size: SH
  1. Coat the O-ring seal and the cleaned surface of the plug opening with water resistant high-temperature grease lubricant GM P/N 9985164 (Canadian P/N 10953480), or the equivalent.

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

  2. Tightly push the coolant heater (1) into the engine block.

    3. 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.


    Object Number: 312945 Size: SH
  3. Tighten the coolant heater bolt until both of the locking wings draw tightly against the inner wall of the engine block.

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


    Object Number: 312949 Size: SH

    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.

  4. Connect the heater cord to the coolant heater (4).
  5. Fill the cooling system. Refer to Cooling System Draining and Filling .
  6. Inspect the cooling system for leaks.

Coolant Heater Replacement 4.8L/5.3L (except RPO L33) 6.0L

Removal Procedure

    Object Number: 661139 Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling .
  2. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle .
  3. Disconnect the coolant heater electrical connector (2).

    4. Object Number: 661276 Size: SH

    Important: Do not score the surface of the engine block hole when removing the coolant heater.

  4. Remove the coolant heater from the engine block.
  5. Remove any burrs, sealer, paint or other rough spots.

Installation Procedure

    Object Number: 661276 Size: SH
  1. If re-using the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.

    2. 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.

  2. Install the coolant heater to the engine block.

    3. Tighten
    Tighten the coolant heater to 50 N·m (37 lb ft).


    Object Number: 661139 Size: SH

    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.

  3. Connect the coolant heater electrical connector (2).
  4. Lower the vehicle.
  5. Fill the cooling system. Refer to Cooling System Draining and Filling .

Coolant Heater Replacement 8.1L

Removal Procedure

    Object Number: 751506 Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling .
  2. Disconnect the block heater cord from the block heater.

    3. Object Number: 635660 Size: SH
  3. Remove the engine block heater.

Installation Procedure

    Object Number: 635660 Size: SH
  1. Apply sealant GM P/N 12346004, (Canadian P/N 10953480), or equivalent to the threads of the engine block heater.

    2. 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.

  2. Install the engine block heater into the block.

    3. Tighten
    Tighten the coolant heater to 60 N·m (40 lb ft).


    Object Number: 751506 Size: SH

    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.

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

Coolant Heater Replacement 6.6L

Removal Procedure

    Object Number: 674570 Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling .
  2. Remove the right front tire and wheel. Refer to Tire and Wheel Removal and Installation .
  3. Remove the right engine mount. Refer to Engine Mount Replacement - Right Side .
  4. Disconnect the engine coolant heater cord.

    5. Object Number: 663089 Size: SH
  5. Loosen the coolant heater bolt.
  6. Remove the engine coolant heater from the engine block.
  7. Do not score the machined surface of the hole.
  8. Grasp the plug with pliers.
  9. Pull the plug from the engine block.
  10. Clean the core plug hole in order to remove the following substances:
    11. • Burrs
    • Compound
    • Paint
    • Rough spots

Installation Procedure

    Object Number: 663089 Size: SH
  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.

    2. Important: 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.

    4. 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.


    Object Number: 312945 Size: SH
  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.

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


    Object Number: 674570 Size: SH

    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. Remove the right engine mount. Refer to Engine Mount Replacement - Right Side .
  7. Install the right front tire and wheel. Refer to Tire and Wheel Removal and Installation .
  8. Fill the cooling system. Refer to Cooling System Draining and Filling .
  9. Inspect for coolant leaks.

Coolant Heater Replacement 5.3L (w/RPO L33)

Removal Procedure
  1. Remove the engine protection shield. Refer to Engine Protection Shield Replacement .
  2. Remove the front drive axle shield. Refer to Shield Replacement .
  3. Drain the cooling system. Refer to Cooling System Draining and Filling .
  4. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .

    5. Object Number: 673597 Size: SH
  5. Disconnect the coolant heater electrical connector.

    6. Important: Do not score the surface of the engine block hole when removing the coolant heater.

  6. Remove the coolant heater from the engine block.
  7. Remove any burrs, sealer, paint or other rough spots.

Installation Procedure
  1. If reusing the old coolant heater, apply thread sealant to the to the threads. Refer to Adhesives, Fluids, Lubricants, and Sealers for the correct part number.

    2. Notice: Refer to Fastener Notice in the Preface section.

  2. Install the coolant heater to the engine block.

    3. Tighten
    Tighten the coolant heater to 50 N·m (37 lb ft).


    Object Number: 673597 Size: SH

    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.

  3. Connect the coolant heater electrical connector.
  4. Lower the vehicle.
  5. Fill the cooling system. Refer to Cooling System Draining and Filling .
  6. Install the front drive axle shield. Refer to Shield Replacement .
  7. Install the engine protection shield. Refer to Engine Protection Shield Replacement .