1999 GM 6.5L V8 – Water Pump Clean and Inspect

Important:

• The water pump used with the serpentine belt system rotates counterclockwise (CCW ). Replace the pump only with the proper part number or engine overheating may occur, causing damage to the engine.

• Do not immerse the water pump in solvent.
Solvent will dissolve the lubricant supply for the permanently lubricated bearings, causing premature bearing failure.

1. Clean the old gasket off of the gasket surfaces on the water pump and the water pump backing plate.

2. Replace the water pump if the following conditions exist:
• Excessive end play in the pump shaft (0.20 mm /0.008 in end play is normal).
• Pump drive shaft will not rotate smoothly (binding or roughness).
– If the pump has been dry for a while it may be difficult to turn the shaft on the first try.
– If the pump does not turn smoothly after a few attempts, replace the water pump.

• Coolant leakage at the water pump drain hole.
• Damage to the water pump sealing surface.
• Damage to the water pump pulley.

3. Replace the water pump backing plate if the following condition exists:
• Damage to the water pump backing plate sealing surface.
• Damage to the oil fill tube seal flange.

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