GM Full-Size Trucks 1988-1998 Repair Information

Water Pump

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REMOVAL & INSTALLATION



4.8L Engines

See Figure 1



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Fig. Fig. 1: Water pump installation-4.8L engines


CAUTION
Never open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the radiator.
  4.  
  5. Loosen the alternator and other accessories at their adjusting points, and remove the fan belts from the fan pulley.
  6.  
  7. Remove the fan, fan clutch and pulley.
  8.  
  9. Remove any accessory brackets that might interfere with water pump removal.
  10.  
  11. Disconnect the hose from the water pump inlet and the heater hose from the nipple on the pump. Remove the bolts, pump assembly and old gasket from the timing chain cover.
  12.  

To install:
  1. Make sure the gasket surfaces on the pump and engine block are clean.
  2.  
  3. Install the pump assembly with a new gasket. Tighten the bolts to 15 ft. lbs. (20 Nm).
  4.  
  5. Connect the hose between the water pump inlet and the nipple on the pump.
  6.  
  7. Install any accessory brackets.
  8.  
  9. Install the fan and pulley.
  10.  
  11. Install and adjust the alternator and other accessories.
  12.  
  13. Install the fan belts from the fan pulley.
  14.  
  15. Fill the cooling system.
  16.  
  17. Connect the battery.
  18.  

4.3L, 5.0L, 5.7L and 7.4L Engines

See Figures 2, 3, 4, 5, 6, 7 and 8



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Fig. Fig. 2: Disconnect the lower radiator hose from the water pump inlet



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Fig. Fig. 3: Remove the water pump attaching bolts


CAUTION
Never open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the coolant from the radiator. Remove the upper fan shroud.
  4.  
  5. Remove the drive belt(s).
  6.  
  7. Remove the alternator and other accessories, if necessary.
  8.  
  9. Remove the fan, fan clutch and pulley.
  10.  
  11. Remove any accessory brackets that might interfere with water pump removal.
  12.  
  13. Disconnect the lower radiator hose from the water pump inlet and the heater hose from the nipple on the pump. On the 7.4L engine, remove the bypass hose.
  14.  
  15. Remove the bolts, then pull the water pump assembly away from the timing cover.
  16.  

To install:
  1. Clean all old gasket material from the timing chain cover.
  2.  
  3. Install the pump assembly with a new gasket. Tighten the bolts to 30 ft. lbs. (41 Nm).
  4.  
  5. Connect the hose between the water pump inlet and the nipple on the pump. Connect the heater hose and the bypass hose (7.4L only).
  6.  
  7. Install the fan, fan clutch and pulley.
  8.  
  9. Install and adjust the alternator and other accessories, if necessary.
  10.  
  11. Install the drive belt(s). Install the upper radiator shroud
  12.  
  13. Fill the cooling system. Connect the battery.
  14.  



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Fig. Fig. 4: Remove the water pump from the vehicle



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Fig. Fig. 5: Using a scraper, clean the old gasket from both mating surfaces of the water pump



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Fig. Fig. 6: Water pump installation-4.3L engines



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Fig. Fig. 7: Water pump installation-5.0L and 5.7L engines



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Fig. Fig. 8: Water pump installation-7.4L engines

6.2L and 6.5L Diesel Engines

See Figure 9



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Fig. Fig. 9: Water pump mounting-6.2L and 6.5L diesel engines


CAUTION
Never open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Disconnect the batteries, negative cable first.
  2.  
  3. Drain the radiator.
  4.  
  5. Remove the fan shroud and fan.
  6.  
  7. Remove the drive belt(s).
  8.  
  9. On 6.2L diesel engines that are equipped with air conditioning, remove the air conditioning hose bracket nuts.
  10.  
  11. On early model diesel engines, remove the oil filler tube.
  12.  
  13. If necessary for access, unfasten the generator pivot bolt and remove the generator lower bracket.
  14.  
  15. On late model diesel engines, remove the vacuum pump and bracket.
  16.  
  17. On late model diesel engines, remove the power steering pump and lay it aside, then remove the pump bracket.
  18.  
  19. Disconnect the bypass hose and the lower radiator hose.
  20.  
  21. Remove the water pump bolts.
  22.  
  23. Remove the water pump plate and gasket and water pump.
  24.  
  25. If the pump gasket is to be replaced, unfasten the plate attaching bolts to the water pump and remove (and replace) the gasket.
  26.  

To install:
  1. Attach the water pump to the plate assembly. Tighten the bolts to 31 ft. lbs. (42 Nm).
  2.  
  3. When installing the pump, the flanges must be free of oil. Apply an anaerobic sealer (GM part #1052357 or equivalent) to the sealing surfaces A shown in the accompanying illustration.
  4.  

The sealer must be wet to the touch when the bolts are tightened.

  1. Install the pump and plate assembly to the engine and install the pump-to-engine bolts. Tighten the bolts to 17 ft. lbs. (23 Nm), except the three lower right side bolts. Tighten these bolts to 31 ft. lbs. (42 Nm).
  2.  
  3. Connect the bypass hose and the lower radiator hose.
  4.  
  5. If removed, install the power steering pump and mounting bracket.
  6.  
  7. If removed, install the generator lower bracket.
  8.  
  9. If removed, install the generator pivot bolt.
  10.  
  11. If removed, install the drive belt(s).
  12.  
  13. Install the oil filler tube.
  14.  
  15. On 6.2L engines equipped with air conditioning, install the air conditioning hose bracket nuts.
  16.  
  17. Fill the radiator.
  18.  
  19. Install the fan and fan shroud.
  20.  
  21. Connect the batteries.
  22.  

 
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