GM Corvette 1984-1996 Repair Guide

Thermostat

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REMOVAL & 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.

5.7L (VIN 8) Engines

See Figures 1 and 2

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air intake duct and air cleaner assembly.
  4.  
  5. Making sure the engine is cool, remove the surge tank cap.
  6.  
  7. Drain the cooling system, to a level below the thermostat, into a suitable container.
  8.  
  9. Use a suitable pair of pliers to unfasten the hose clamp, then disconnect the upper radiator hose from the outlet.
  10.  
  11. For 1990-91 vehicles, perform the following:
    1. Disconnect the coolant hose from the throttle body.
    2.  
    3. Detach the electrical connector and vacuum harness at the EGR solenoid.
    4.  

  12.  
  13. Unfasten the thermostat housing attaching bolts, then remove the housing. Remove the thermostat from the manifold.
  14.  



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the thermostat and water pump assembly-1984-89 5.7L (VIN 8) engine



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of the thermostat and water pump assembly-1990-91 5.7L (VIN 8) engine

  1. Thoroughly clean the gasket mating surfaces of the water outlet and upper intake manifold.
  2.  

To install:
  1. For 1984-89 vehicles, perform the following:
    1. Place a 1 / 8 in. (3mm) bead of RTV sealant, all around the thermostat housing sealing surface on the intake manifold.
    2.  
    3. Place the thermostat in the intake manifold.
    4.  
    5. While the RTV is still wet, position the thermostat housing. Tighten the housing retaining bolts to 18-23 ft. lbs. (24-31 Nm).
    6.  

  2.  
  3. For 1990-91 vehicles, perform the following:
    1. Install the thermostat, a new gasket, and the housing on the manifold.
    2.  
    3. Install the housing bolts and tighten to 25 ft. lbs. (34 Nm).
    4.  
    5. Attach the electrical connector and vacuum harness at the EGR solenoid.
    6.  
    7. Connect the coolant hose to the throttle body.
    8.  

  4.  
  5. Install the air cleaner assembly and air intake duct.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Start the engine and run, with the radiator cap removed, until the upper radiator hose is hot (thermostat open).
  10.  
  11. With the engine idling, add a suitable coolant/water mixture until the level reaches the bottom of the radiator filler neck.
  12.  
  13. Install the radiator cap, making sure the arrows line up with the overflow tube.
  14.  
  15. Turn the engine off, then recheck the coolant level and add if necessary, through the recovery reservoir.
  16.  

5.7L (VIN J) Engine

See Figure 3

This procedure covers removal of the thermostat and housing.

  1. Disconnect the negative battery cable.
  2.  
  3. Making sure the engine is cool, remove the surge tank cap.
  4.  
  5. Drain the cooling system into a suitable container.
  6.  
  7. Raise and safely support the vehicle.
  8.  
  9. Unfasten the bolts retaining the thermostat housing assembly brackets to the front side member.
  10.  
  11. Use a suitable pair of pliers to unfasten the clamps securing the following hoses from the thermostat:

    Radiator outlet hose
     
    Radiator bypass hose
     
    Engine hose
     

  12.  
  13. Detach the quick-connect fittings at the heater hose-thermostat housing junction.
  14.  
  15. Remove the thermostat housing assembly from the vehicle.
  16.  
  17. Unfasten the housing bolts, then remove the thermostat and seal.
  18.  
  19. Inspect the housing for hairline cracks or other damage. If you are replacing the housing, transfer the necessary parts to the new housing.
  20.  



Click image to see an enlarged view

Fig. Fig. 3: Exploded view of the thermostat and housing assemblies

  1. Thoroughly clean the gasket mating surfaces of the thermostat housing.
  2.  

To install:

The seal on the thermostat MUST be installed with the taper toward the radiator. Make sure the seal remains seated in the housing groove when assembling the housing sections.

  1. Place the thermostat and seal in the housing.
  2.  
  3. Install the thermostat housing bolts and tighten to 18 ft. lbs. (25 Nm).
  4.  
  5. Attach the quick-connect fittings at the heater hose-thermostat housing junction.
  6.  
  7. Connect the following hoses and secure with the hose clamps:

    Radiator outlet hose
     
    Radiator bypass hose
     
    Engine hose
     

  8.  
  9. Tighten the hose clamps to 35 inch lbs. (4 Nm).
  10.  
  11. Install the bolts holding the thermostat housing brackets to the front side member. Tighten the bolts to 18 ft. lbs. (25 Nm).
  12.  
  13. Carefully lower the vehicle.
  14.  
  15. Refill the engine cooling system with the proper type and amount of coolant.
  16.  

5.7L (VIN P and 5) Engines

See Figures 4, 5 and 6

On these vehicles, when adding cooling you must use DEX-COOL®, or equivalent orange colored, silicate-free coolant.

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the Intake Air Temperature (IAT) sensor electrical connector.
  4.  



Click image to see an enlarged view

Fig. Fig. 4: Unplug the IAT sensor electrical connector. The IAT sensor is located in the air cleaner intake duct

  1. Remove the air intake duct and air cleaner.
  2.  



Click image to see an enlarged view

Fig. Fig. 5: Unfasten the retainers, then remove the air intake duct

  1. Use a suitable pair of pliers to unfasten the hose clamp, then disconnect the lower radiator hose from the thermostat housing inlet of the water pump.
  2.  
  3. Unfasten the thermostat housing bolts, then remove the housing. Remove the thermostat and the gasket.
  4.  
  5. Throroughly clean the thermostat housing and water pump gasket mating surfaces.
  6.  



Click image to see an enlarged view

Fig. Fig. 6: Exploded view of the thermostat housing and thermostat

To install:
  1. Install the thermostat and gasket with the taper up. Install the housing and bolts to the water pump. Tighten the housing bolts to 89 inch lbs. (10 Nm).
  2.  
  3. Attach the radiator lower hose on the inlet side of the water pump. Secure the hose with the retaining clamp.
  4.  
  5. Fill the cooling system to the proper level with a 50/50 mixture of DEX-COOL® or equivalent, silicate free coolant.
  6.  
  7. Install the air cleaner and air intake duct.
  8.  
  9. Attach the IAT sensor electrical connector.
  10.  
  11. Connect the negative battery cable. Start the engine and check for coolant leaks. Check the coolant level and add if necessary.
  12.  

 
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