Coolant Heater Replacement

Coolant Heater Replacement (LL8) (4.2L)

Removal Procedure

1. Drain the engine coolant. Refer to Cooling System Draining and Filling (LH6) (Cooling System Draining and Filling)Cooling System Draining and Filling (LL8) (Cooling System Draining and Filling).




2. Remove the powertrain control module (PCM) retaining bolts (3) and nuts (6).
3. Remove the PCM mounting studs (5) and position the PCM out of the way.




4. Disconnect the engine coolant temperature (ECT) sensor electrical connector (1).





Caution: Refer to Fuel and Evaporative Emission Hose/Pipe Connection Cleaning Caution (Vehicle Damage Warnings).

5. Disconnect the fuel feed (1) and fuel return (2) pipes from the fuel rail. Refer to Metal Collar Quick Connect Fitting Service (Metal Collar Quick Connect Fitting Service).
6. Disconnect the integral clip (3) from the wire harness bracket.




7. Remove the engine wire harness bracket bolt.
8. Position the engine electrical wire harness bracket with wires attached out of the way.




9. Remove the coolant heater cord from the heater (2).





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

10. Remove the coolant heater from the block.

Installation Procedure

1. Remove any burrs, sealer, paint or other foreign material from the threads/sealing surface of the engine block and from the old coolant heater if the heater is to be reused.
2. If reusing the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.





Caution: Refer to Fastener Caution (Fastener Caution).

3. Install the coolant heater to the engine block and tighten to 50 Nm (37 ft. lbs.).




4. Install the coolant heater cord to the heater (2).
5. Properly position the engine electrical harness bracket to the intake manifold.





Caution: Refer to Fastener Caution (Fastener Caution).

6. Install the engine electrical harness bracket bolt and tighten to 10 Nm (89 in. lbs.).




7. Connect the integral clip (3) to the wire harness bracket.
8. Connect the fuel feed (1) and fuel return (2) pipes to the fuel rail. Refer to Metal Collar Quick Connect Fitting Service (Metal Collar Quick Connect Fitting Service).




9. Connect the ECT sensor electrical connector (1).




10. Install the PCM mounting studs (5) to the intake manifold and tighten to 6 Nm (53 in. lbs.).
11. Install the PCM (1) onto the studs (5).
12. Install the PCM retaining bolts (3) and tighten to 8 Nm (71 in. lbs.).
13. Install the PCM retaining nuts (6) and tighten to 8 Nm (71 in. lbs.).
14. Fill the cooling system. Refer to Cooling System Draining and Filling (LH6) (Cooling System Draining and Filling)Cooling System Draining and Filling (LL8) (Cooling System Draining and Filling).