GM Full Size Vans 1987-1997 Repair Guide

Thermostat

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CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

REMOVAL & INSTALLATION



Gasoline Engines

See Figures 1 through 5



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Fig. Fig. 1: If access is difficult with the hose attached ...



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Fig. Fig. 2:



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Fig. Fig. 3: Once the housing is free, carefully lift it from the engine to expose the thermostat:

  1. Disconnect the negative battery cable and remove the engine cover.
  2.  
  3. Remove the air cleaner and intake duct.
  4.  
  5. If applicable, remove the coolant recovery reservoir.
  6.  
  7. Drain the radiator until the coolant is below the thermostat level (below the level of the intake manifold).
  8.  
  9. Remove the upper radiator hose from the outlet elbow.
  10.  
  11. Remove the water outlet elbow assembly from the engine. Remove the thermostat from the engine.
  12.  



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Fig. Fig. 4: Sometimes, the thermostat will lift from the engine with the housing ...:



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Fig. Fig. 5: ...otherwise, note the direction it is installed, then lift the thermostat from the engine

To install:
  1. Clean the gasket surfaces on the water outlet elbow and the intake manifold. Use a new gasket when installing the elbow to the manifold.
  2.  
  3. Install the new thermostat making sure the spring side is inserted into the engine. Tighten the thermostat housing bolts as follows:

    1987-95 4.3L, 5.0L and 5.7L models; 21 ft. lbs. (28 Nm)
     
    1996-97 4.3L, 5.0L and 5.7L models; 18 ft. lbs. (25 Nm)
     
    1987-95 7.4L models; 27 ft. lbs. (37 Nm)
     
    1996-97 7.4L models; 30 ft. lbs. (40 Nm)
     

  4.  
  5. Connect the upper radiator hose to the outlet elbow.
  6.  
  7. If applicable, install the coolant recovery reservoir.
  8.  
  9. Install the air cleaner and intake duct.
  10.  
  11. Connect the negative battery cable and install the engine cover.
  12.  
  13. Refill the cooling system. Start the engine and check for leaks.
  14.  

See Figures 6 through 10



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Fig. Fig. 6: Thermostat housing - carbreted and TBI 4.3L engines



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Fig. Fig. 7: Thermostat housing - carbreted and TBI 5.0L and 5.7L engines



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Fig. Fig. 8: Thermostat housing - 1996-97 4.3L engines



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Fig. Fig. 9: Thermostat housing - 1996-97 5.0L and 5.7L engines



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Fig. Fig. 10: Thermostat housing - 1996-97 7.4L engines

6.2L and 6.5L Diesel Engines

See Figures 11 and 12



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Fig. Fig. 11: Thermostat housing - 1987-95 diesel engines



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Fig. Fig. 12: Thermostat housing - 1996-97 diesel engines

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the upper fan shroud.
  4.  
  5. Drain the cooling system to a point below the thermostat.
  6.  
  7. Remove the engine oil dipstick tube brace and the oil fill brace.
  8.  
  9. Remove the upper radiator hose.
  10.  
  11. Remove the water outlet.
  12.  
  13. Remove the thermostat and gasket.
  14.  
  15. Installation is the reverse of removal.
  16.  
  17. Use a new gasket coated with sealer, Make sure that the spring end of the thermostat is in the engine. Tighten the bolts to 35 ft. lbs. (47 Nm) on 1987-91 models and 31 ft. lbs. (42 Nm) on 1992-97 models.
  18.  

 
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