Coolant Heater Replacement (RPOs LY2/LMG/LY5/LY6)

Coolant Heater Replacement (RPOs LY2/LMG/LY5/LY6) (4.8L, 5.3L and 6.0L)

Removal Procedure





1. Drain the cooling system/engine block. Refer to Cooling System Draining and Filling (Static Fill) (Service and Repair) .
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
3. For 1500 series vehicles, remove the oil pan skid plate bolts and plate, if equipped.




4. For 2500 series vehicle, remove the front 2 oil pan skid plate bolts, loosen the 2 rear bolts and remove the skid plate, if equipped.




5. For vehicles with regular production option (RPO) LY6 (6.0L) perform the following steps otherwise proceed to step 10.
6. Remove the oil cooler hose bracket bolt (1).
7. Remove the oil cooler hose adapter bolts (2).
8. Remove and discard the oil cooler hose adapter gasket.
9. Reposition the oil cooler hose adapter end out of the way.




10. Disconnect the coolant heater cord electrical connector.





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


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



Installation Procedure





1. If reusing the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.

Notice: Refer to Fastener Notice .

2. Install the coolant heater to the engine block.

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





3. Connect the coolant heater cord electrical connector.




4. For vehicles with RPO LY6 (6.0L) perform the following steps otherwise proceed to step 9.
5. Position the oil cooler hose adapter end.
6. Install a NEW oil cooler hose adapter gasket.
7. Install the oil cooler hose adapter bolts (2).

Tighten the bolts to 12 N.m (106 lb in).

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

Tighten the bolt to 25 N.m (18 lb ft).





9. For 2500 series vehicles, position the oil pan skid plate and install the 2 front bolts and tighten the 2 rear bolts, if equipped.

Tighten the bolts to 20 N.m (15 lb ft).





10. For 1500 series vehicles position and install the oil pan skid plate and bolts, if equipped.

Tighten the bolts to 20 N.m (15 lb ft).

11. Lower the vehicle.
12. Fill the cooling system/engine block. Refer to Cooling System Draining and Filling (Static Fill) (Service and Repair) .