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For 1990-2009 cars only

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

  3. Tightly push the coolant heater (1) into the engine block.
  4. Caution: Refer to Fastener Caution in the Preface section.


    Object Number: 312945  Size: SH
  5. Tighten the coolant heater bolt until both of the locking wings draw tightly against the inner wall of the engine block and tighten to 2 N·m (18 lb in).

  6. Object Number: 312949  Size: SH

    Caution: 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.

  7. Connect the heater cord to the coolant heater (4).
  8. Fill the cooling system. Refer to Cooling System Draining and Filling.
  9. 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

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

  5. Remove the coolant heater from the engine block.
  6. 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. Caution: Refer to Fastener Caution in the Preface section.

  3. Install the coolant heater to the engine block and tighten to 50 N·m (37 lb ft).

  4. Object Number: 661139  Size: SH

    Caution: 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 coolant heater electrical connector (2).
  6. Lower the vehicle.
  7. Fill the cooling system. Refer to Cooling System Draining and Filling.

Coolant Heater Replacement 4.8L/5.3L/6.0L

Removal Procedure

  1. Drain the cooling system/engine block. Refer to Cooling System Draining and Filling.
  2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.

  3. Object Number: 1702199  Size: SH
  4. For vehicles with regular production option (RPO) L76 (6.0L), perform the following steps. Otherwise, proceed to step 8.
  5. Remove the oil cooler hose bracket bolt (1), if equipped.
  6. Remove the oil cooler hose adapter bolts (2), if equipped.
  7. Remove and discard the oil cooler hose adapter gasket, if equipped.
  8. Position the oil cooler hose adapter end out of the way, if equipped.

  9. Object Number: 1815342  Size: SH
  10. Disconnect the coolant heater cord electrical connector (1).

  11. Object Number: 1702201  Size: SH

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

  12. Remove the coolant heater from the engine block.
  13. Remove any burrs, sealer, or other rough spots.

Installation Procedure


    Object Number: 1702201  Size: SH
  1. If reusing the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.
  2. Caution: Refer to Fastener Caution in the Preface section.

  3. Install the coolant heater to the engine block and tighten to 50 N·m (37 lb ft).

  4. Object Number: 1815342  Size: SH
  5. Connect the coolant heater cord electrical connector (1).

  6. Object Number: 1702199  Size: SH
  7. For vehicles with RPO L76 (6.0L) perform the following steps otherwise proceed to step 10.
  8. Position the oil cooler hose adapter end, if equipped.
  9. Install a NEW oil cooler hose adapter gasket, if equipped.
  10. Install the oil cooler hose adapter bolts (2), if equipped and tighten to 12 N·m (106 lb in).
  11. Install the oil cooler hose bracket bolt (1), if equipped and tighten to 25 N·m (18 lb ft).
  12. Lower the vehicle.
  13. Fill the cooling system/engine block. 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. Disconnect the engine coolant heater cord.

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

  3. Align the coolant heater element to point towards the top of the engine.
  4. Tightly push the coolant heater into the engine block.
  5. Caution: Refer to Fastener Caution in the Preface section.


    Object Number: 312945  Size: SH
  6. Tighten the bolt on the engine coolant heater until both of the locking wings draw tightly against the inner wall of the engine block and tighten to 2 N·m (18 lb in).

  7. Object Number: 674570  Size: SH

    Caution: 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.

  8. Connect the heater cord to the coolant heater.
  9. Install the right front tire and wheel. Refer to Tire and Wheel Removal and Installation.
  10. Fill the cooling system. Refer to Cooling System Draining and Filling.
  11. Inspect for coolant leaks.