Water Pump Replacement L65

1. Drain the coolant from the radiator. Refer to Cooling System Draining and Filling .
2. Remove the fan shroud. Refer to Fan Shroud Replacement .
3. Remove the drive belt. Refer to Drive Belt Replacement in Engine Mechanical - 6.5L.
4. Remove the fan and fan clutch. Refer to Fan Clutch Replacement .
5. Raise the vehicle. Support the vehicle with safety stands. Refer to Lifting and Jacking the Vehicle in General Information.
6. Remove the following vacuum pump components. Refer to Vacuum Pump Replacement in Engine Mechanical - 6.5L:

6.1.	The mounting bracket nuts

6.2.	The bolt securing the vacuum pump bracket and the generator

6.3.	The vacuum pump and the bracket

7. Remove the power steering pump. Do not disconnect the hoses. Lay the pump aside. Refer to Power Steering Pump Replacement in Power Steering System.
8. Lower the vehicle.
9. Remove the bolts, the studs, the water pump backing plate and the water pump.



10. Disconnect the lower radiator hose from the water pump.



11. Disconnect the bypass hose from the water pump.



12. Remove the water pump and backing plate bolts from the engine.
13. Remove the water pump with the backing plate from the engine.



14. Remove the bolts from the rear of the water pump backing plate.
15. Remove the water pump from the backing plate.
16. Remove the water pump and the gasket from the backing plate.

Important: All of the flanges must be free of oil.

17. Clean the following mating surfaces:

•	The water pump

•	The water pump backing plate, both sides

•	The engine block

Important: Do not use sealer on the water pump backing plate gasket. The gasket has pre-applied sealer.

1. Install the gasket.
2. Install the water pump to the water pump backing plate.
3. Apply high threadlocker GM P/N 12345493, or equivalent, to the bolt threads.

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.

4. Install the backing plate bolts.

Tighten
Tighten the backing plate bolts to 28 N·m (20 lb ft).




5. Apply gasket maker GM P/N 1052942, or equivalent to the water pump backing plate. The sealer must be wet to the touch when the bolts are installed and tightened.



6. Install the water pump and the water pump backing plate to the engine.
7. Install the bolts and the studs.

Tighten

•	Tighten the water pump to front cover bolts to 42 N·m (31 lb ft).

•	Tighten the water pump plate to front cover bolts to 28 N·m (20 lb ft).




8. Connect the bypass hose.



9. Connect the lower radiator hose. Refer to .
10. Install the power steering bracket and the pump. Refer to Power Steering Pump Replacement in Power Steering System.
11. Raise the vehicle.
12. Install the vacuum pump and the bracket. Refer to Vacuum Pump Replacement in Engine Mechanical - 6.5L.
13. Lower the vehicle.
14. Install the fan and fan clutch assembly and the water pump pulley. Refer to Fan Clutch Replacement .
15. Install the drive belt. Refer to Drive Belt Replacement in Engine Mechanical - 6.5L.
16. Install the fan shroud. Refer to Fan Shroud Replacement .
17. Fill the surge tank with coolant. Refer to Cooling System Draining and Filling .
18. Start the engine. Run the engine with the surge tank cap removed, until the upper radiator hose becomes hot. This indicates that the thermostat is open.
19. While the engine is running at idle speed, add coolant to the surge tank until the level reaches the FULL mark. Refer to Cooling System Draining and Filling .



20. Install the surge tank cap. Make sure the cap arrows line up with the overflow tube.
21. Inspect the cooling system for leaks.

Water Pump Replacement 8.1L Engine

1. Drain the cooling system. Refer to Cooling System Draining and Filling .
2. Remove the drive belt tensioner. Refer to Drive Belt Tensioner Replacement in Engine Mechanical - 8.1L.
3. Remove the fan. Refer to Fan Clutch Replacement .
4. Reposition the outlet hose clamp (6) at the water pump.
5. Remove the outlet hose (5) from the water pump.



6. Reposition the bypass hose clamps at the water pump and crossover.
7. Remove the bypass hose.



8. Remove the water pump bolts.
9. Remove the water pump and gaskets. Discard the gaskets.

1. Place NEW water pump gaskets and the water pump into position.

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 water pump bolts.

Tighten
Tighten the water pump bolts to 50 N·m (37 lb ft).




3. Install the bypass hose.
4. Position the bypass hose clamps at the water pump and crossover.



5. Install the outlet hose (5) to the water pump.
6. Position the outlet hose clamp (6) at the water pump.
7. Install the fan. Refer to Fan Clutch Replacement .
8. Install the drive belt tensioner. Refer to Drive Belt Tensioner Replacement in Engine Mechanical - 8.1L.
9. Fill the cooling system. Refer to Cooling System Draining and Filling .