GM Lumina/Silhouette/Transport APVs 1990-1999 Repair Guide

Water Pump

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The water pump is a centrifugal-type pump consisting of an impeller, impeller drive shaft, pulley flange, and cast housing. The serpentine belt drives the pulley that attaches to the pump. The water pump draws coolant from the radiator, through the lower hose, circulates it through the coolant jackets in the engine block, intake manifold, and cylinder heads, and then directs it back to the radiator, where it is cooled, through the upper hose.

REMOVAL AND INSTALLATION




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.3.1L Engine

  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant into a suitable container.
  4.  
  5. Disconnect the heater hose.
  6.  
  7. Remove the serpentine belt shield.
  8.  
  9. With a 3 / 8 breaker-bar, relieve tension in the serpentine belt.
  10.  
  11. Remove the water pump pulley.
  12.  
  13. Unfasten the retainers, then remove the water pump. Remove and discard the gasket.
  14.  
  15. Thoroughly clean the gasket mating surfaces.
  16.  

See Figure 1

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Fig. Fig. 1: Exploded view of the water pump mounting-3.1L engine

To install:
  1. Position a new gasket, then install the water pump. Tighten the attaching bolts to 89 inch lbs. (10 Nm).
  2.  
  3. Install the water pump pulley.
  4.  
  5. Install the serpentine belt, then replace the serpentine belt shield.
  6.  
  7. Connect the heater hose.
  8.  
  9. Refill the cooling system.
  10.  
  11. Connect the negative battery cable.
  12.  

3.4L Engine

  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant into a suitable container.
  4.  
  5. Remove the serpentine belt guard, bolts and nuts.
  6.  
  7. Loosen the water pump pulley bolts. Do not remove the bolts until the belt is removed.
  8.  
  9. Remove the serpentine belt.
  10.  
  11. Remove the water pump pulley.
  12.  
  13. Remove the water pump and gasket.
  14.  
  15. Thoroughly clean the gasket mating surfaces.
  16.  

See Figure 2

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Fig. Fig. 2: Water pump mounting-3.4L engine

To install:
  1. Install the water pump with a new gasket.
  2.  
  3. Install the water pump pulley and loosely install the attaching bolts.
  4.  
  5. Install the serpentine belt.
  6.  
  7. Tighten the water pump pulley bolts to 18 ft. lbs. (25 Nm)
  8.  
  9. Install the serpentine belt guard, bolts and nuts.
  10.  
  11. Refill the coolant system.
  12.  

3.8L Engine

  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant into a suitable container.
  4.  
  5. Loosen the water pump pulley bolts. Do not remove the bolts until the belt is removed.
  6.  

See Figure 3

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Fig. Fig. 3: Loosen the pulley mounting bolts before releasing the belt tension

  1. Release the serpentine drive belt tension, then remove the belt.
  2.  
  3. Remove the water pump pulley.
  4.  

See Figure 4

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Fig. Fig. 4: After the serpentine belt is removed, you can remove the water pump pulley

As you remove the water pump mounting bolts, make sure to note the locations that they came from, as they are two different lengths.

  1. Unfasten the retainers, then remove the water pump and gasket. If the water pump is stuck to the engine, there is a small notch in which you can insert a small prytool. Be extremely carefully if you have to pry the water pump off! Discard the gasket.
  2.  

See Figures 5, 6, 7 and 8

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Fig. Fig. 5: Unfasten the water pump mounting bolts



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Fig. Fig. 6: Attempt to pull the water pump off the engine



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Fig. Fig. 7: If you can't pull the water pump off, there is a provision made for a small prytool. Be very careful when prying the water pump off!



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Fig. Fig. 8: It doesn't take much pressure with a prytool to release the water pump from the gasket.

  1. Thoroughly clean the gasket mating surfaces.
  2.  

See Figures 9, 10 and 11

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Fig. Fig. 9: Use a suitable tool to scrape the gasket material from the engine ...



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Fig. Fig. 10: ... and from the old water pump assembly



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Fig. Fig. 11: Make a note, or mark the bolts, because they are two different lengths

To install:
  1. Attach a new gasket to the water pump.
  2.  

See Figure 12

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Fig. Fig. 12: Make sure the mating surfaces are clean before affixing a new gasket to the water pump

  1. Install the water pump to the engine. Tighten the mounting bolts to the specifications given in accompanying figure.
  2.  

See Figure 13

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Fig. Fig. 13: Water pump mounting and tightening specifications-3.8L engine

  1. Install the water pump pulley. Loosely install the mounting bolts.
  2.  
  3. Install the serpentine drive belt.
  4.  
  5. Tighten the pump pulley bolts.
  6.  
  7. Refill the coolant system.
  8.  
  9. Connect the negative battery cable.
  10.  

 
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