GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2005 🢒 H2 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Coolant Heater Replacement

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

    3. Object Number: 688324 Size: SH
  3. Remove the oil cooler hose bracket bolt (1).
  4. Remove the oil cooler hose adapter bolts (2).
  5. Remove and discard the oil cooler hose adapter gasket.
  6. Position the oil cooler hose adapter end out of the way.

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


    Object Number: 786910 Size: SH
  7. Install the coolant heater in place of the drain plug.

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


    Object Number: 661139 Size: SH

    Important: The engine coolant heater cord must not touch the engine, hot pipes, manifold, or any moving parts. Always keep the electrical cord neatly rolled up with the end of the cord tucked in the center of the coil and secured in place.

  8. Push the engine coolant heater cord electrical connector (2) firmly into the coolant heater (1).

    9. Object Number: 661277 Size: SH
  9. Place the cord into position.

    10. 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.

  10. Install the heater cord bolt and retainer.

    11. Tighten
    Tighten the heater cord bolt to 8 N·m (71 lb in).


    Object Number: 688324 Size: SH
  11. Position the oil cooler hose adapter.
  12. Install a NEW oil cooler hose adapter gasket.
  13. Install the oil cooler hose adapter bolts (2).

    14. Tighten
    Tighten the oil cooler hose adapter bolts to 12 N·m (106 lb in).

  14. Install the oil cooler hose bracket bolt (1).

    15. Tighten
    Tighten the oil cooler hose bracket bolt to 25 N·m (18 lb ft).

  15. Lower the vehicle.
  16. Fill the cooling system/engine block. Refer to Cooling System Draining and Filling .