GM Grand Am/Achieva/Calais/Skylark/Somerset 1985-98

Thermostat

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REMOVAL & INSTALLATION



See Figures 1, 2, 3 and 4


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the 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.

2.0L and 2.5L Engines

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the thermostat housing cap.
  4.  
  5. Grasp the handle of the thermostat, then gently pull it upwards to remove. Remove the gasket/O-ring and replace if damaged.
  6.  
  7. Clean off the thermostat housing and O-ring. After cleaning, apply a suitable lubricant to the O-ring to aid in installation.
  8.  

To install:
  1. Place the thermostat in the housing, pushing down to be sure it is firmly seated.
  2.  
  3. Install the thermostat housing cap.
  4.  
  5. Properly fill the cooling system.
  6.  
  7. Connect the negative battery cable, remove the radiator cap, then start the engine. Allow the engine to run with radiator cap removed, until the upper radiator hose becomes hot (thermostat open). With the engine idling, add coolant to the radiator until the level is up to the bottom of the filler neck.
  8.  
  9. Install the radiator cap.
  10.  



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Fig. Fig. 1: Unfasten the thermostat housing retaining bolts



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Fig. Fig. 2: If not done already, disconnect the throttle body outlet hose



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Fig. Fig. 3: Using a pair of pliers or your hand, remove the thermostat



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Fig. Fig. 4: Using a suitable scraping tool, clean the old gasket material from the housing and mating surfaces

2.3L and 2.4L Engines

1988-93 MODELS
  1. Disconnect the negative battery cable.
  2.  
  3. Properly drain and recover the coolant to a level below the thermostat.
  4.  
  5. Disconnect the upper radiator hose and position it aside.
  6.  
  7. Remove the heater hose and position it aside.
  8.  
  9. Detach the ECT sensor electrical connector.
  10.  
  11. Remove the throttle body coolant hose.
  12.  
  13. Unfasten the thermostat housing retaining bolts, then remove the housing.
  14.  
  15. Remove the thermostat, then clean the gasket material from the mating surfaces.
  16.  

To install:
  1. Position the thermostat, then install the housing, using a new gasket. Tighten to 19 ft. lbs. (26 Nm).
  2.  
  3. Connect the throttle body and heater hoses.
  4.  
  5. Attach the ECT sensor electrical connector.
  6.  
  7. Install the upper radiator hose.
  8.  
  9. Properly fill the cooling system.
  10.  
  11. Connect the negative battery cable, remove the radiator cap, then start the engine. Allow the engine to run with radiator cap removed, until the upper radiator hose becomes hot (thermostat open). With the engine idling, add coolant to the radiator until the level is up to the bottom of the filler neck.
  12.  
  13. Install the radiator cap.
  14.  

1994-98 MODELS

See Figure 5

  1. Disconnect the negative battery cable.
  2.  
  3. Properly drain and recover the coolant to a level below the thermostat.
  4.  
  5. Unfasten the coolant inlet housing bolt, which is accessible through the exhaust manifold.
  6.  



Click image to see an enlarged view

Fig. Fig. 5: View of the thermostat and related components-2.4L engine

  1. Raise and safely support the vehicle.
  2.  
  3. Remove the radiator outlet pipe stud.
  4.  
  5. Remove the second coolant inlet housing bolt, then remove the coolant inlet housing.
  6.  
  7. Remove the thermostat, then clean the old gasket material from the mating surfaces.
  8.  

To install:
  1. Position the thermostat in its correct location, then install the coolant inlet housing using a new gasket. Tighten the retaining bolt to 19 ft. lbs. (26 Nm) on the 2.3L and 10 ft. lbs. (14 Nm) on the 2.4L engine.
  2.  
  3. Install the radiator outlet pipe stud.
  4.  
  5. Carefully lower the vehicle.
  6.  
  7. Install the coolant inlet housing bolt through the exhaust manifold.
  8.  
  9. Properly fill the cooling system.
  10.  
  11. Connect the negative battery cable, remove the radiator cap, then start the engine. Allow the engine to run with radiator cap removed, until the upper radiator hose becomes hot (thermostat open). With the engine idling, add coolant to the radiator until the level is up to the bottom of the filler neck.
  12.  
  13. Install the radiator cap, making sure the arrows line up with the overflow tube.
  14.  

3.0L Engine

  1. Disconnect the negative battery cable.
  2.  
  3. Properly drain the coolant down to a level below the thermostat.
  4.  
  5. Swing aside the air intake duct.
  6.  
  7. Disconnect the throttle body outlet hose.
  8.  
  9. Unfasten the thermostat housing attaching bolts, then remove the housing.
  10.  
  11. Remove the thermostat from the engine.
  12.  
  13. Clean the old gasket material from the housing mating surfaces.
  14.  

To install:
  1. Position the thermostat, be sure it is firmly seated. Use a new gasket.
  2.  
  3. Install the thermostat housing, then tighten the retaining bolts.
  4.  
  5. Connect the throttle body outlet hose.
  6.  
  7. Swing the air intake duct back into its original position.
  8.  
  9. Properly fill the cooling system.
  10.  
  11. Connect the negative battery cable, remove the radiator cap, then start the engine. Allow the engine to run with radiator cap removed, until the upper radiator hose becomes hot (thermostat open). With the engine idling, add coolant to the radiator until the level is up to the bottom of the filler neck.
  12.  
  13. Install the radiator cap, making sure the arrows line up with the overflow tube.
  14.  

3.1L and 3.3L Engines

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the cooling system to a level below the thermostat housing.
  4.  
  5. Remove the air cleaner assembly.
  6.  
  7. Disconnect the surge tank line from the thermostat housing.
  8.  
  9. Remove thermostat housing-to-intake manifold attaching bolt and nut, then remove the housing.
  10.  
  11. Remove the thermostat.
  12.  

To install:
  1. Clean all gasket surfaces completely.
  2.  
  3. Insert the thermostat in the intake manifold.
  4.  
  5. Attach the thermostat housing to the intake manifold.
  6.  
  7. Install the mounting bolt and nut. Tighten to 18 ft. lbs. (25 Nm) for the 3.1L engine. For the 3.3L engine, tighten to 20 ft. lbs. (27 Nm).
  8.  
  9. Install the air cleaner assembly.
  10.  
  11. Connect the surge tank line to thermostat housing.
  12.  
  13. Refill the cooling system.
  14.  
  15. Connect the negative battery cable, remove the radiator cap, then start the engine. Allow the engine to run with radiator cap removed, until the upper radiator hose becomes hot (thermostat open). With the engine idling, add coolant to the radiator until the level is up to the bottom of the filler neck.
  16.  
  17. Install the radiator cap, making sure the arrows line up with the overflow tube.
  18.  

 
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