GM Cavalier/Sunbird/Skyhawk/Firenza 1982-1994

Thermostat

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REMOVAL & INSTALLATION



Poor heater output and slow warmup is often caused by a thermostat stuck in the open position; occasionally one sticks shut causing immediate overheating. Do not attempt to correct a chronic overheating condition by permanently removing the thermostat. Thermostat flow restriction is designed into the system; without it, localized overheating (due to coolant turbulence) may occur, causing expensive troubles.


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.

1.8L and 2.0L OHV Engines
1982-86 VEHICLES

See Figure 1

The thermostat is located inside a housing on the back of the cylinder head. It is not necessary to remove the radiator hose from the thermostat housing when removing the thermostat.

  1. Disconnect the negative battery cable.
  2.  
  3. Properly drain the cooling system into an approved container.
  4.  
  5. Remove the air cleaner.
  6.  
  7. On some models it may be necessary to disconnect the A.I.R. pipe at the upper check valve and the bracket at the water outlet.
  8.  
  9. Disconnect the electrical lead.
  10.  
  11. Remove the two retaining bolts from the thermostat housing and lift up the housing with the house attached. Lift out the thermostat. Clean the mating surfaces.
  12.  



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Fig. Fig. 1: Thermostat mounting - 1985 2.0L engine shown

To install:
  1. Apply a 1 / 8 in. (3mm) bead of silicone sealer to the housing mating surface.
  2.  
  3. Place the thermostat, with the power element down, in housing, then install the water outlet while the sealer is still wet. Tighten the housing retaining bolts to 6 ft. lbs. (8 Nm).
  4.  
  5. Connect the electrical lead.
  6.  
  7. If applicable, attach the A.I.R. pipe at the check valve and bracket at the water outlet.
  8.  
  9. Install the air cleaner.
  10.  
  11. Fill the cooling system to the proper level, using the correct type of fluid.
  12.  
  13. Connect the negative battery cable, then start the engine and check for coolant leaks.
  14.  

1987-89 VEHICLES

See Figure 2

  1. Disconnect the negative battery cable.
  2.  
  3. Properly drain the coolant until the level is below the thermostat.
  4.  
  5. If necessary for access, remove the air cleaner assembly.
  6.  
  7. Unfasten the coolant outlet-to-inlet manifold attaching bolt and nut.
  8.  
  9. Remove the coolant outlet, then remove the thermostat. Remove and discard the gasket, then clean the inlet manifold mating surfaces.
  10.  



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Fig. Fig. 2: Thermostat installation - 1989 2.0L (OHV) engine shown

To install:
  1. Position the thermostat in the inlet manifold.
  2.  

When installing a thermostat, be sure to use a new gasket.

  1. Attach the coolant outlet to the inlet manifold. Coat the attaching bolt and nut with sealer, then tighten to 90 inch lbs. (10 Nm).
  2.  
  3. If removed, install the air cleaner assembly.
  4.  
  5. Refill the engine cooling system to the proper level.
  6.  
  7. Connect the negative battery cable, then start the engine and check for coolant leaks.
  8.  

1.8L and 2.0L OHC Engines

See Figures 3, 4, 5, 6 and 7

  1. Remove the thermostat housing/radiator cap.
  2.  



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Fig. Fig. 3: Remove the radiator cap for access to the thermostat - 1988 2.0L (VIN K) Sunbird shown

  1. Grasp the handle of the thermostat and pull it from the housing.
  2.  



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Fig. Fig. 4: Remove the thermostat by pulling it out by the handle

  1. Clean the thermostat housing and gasket. Replace the gasket if damaged.
  2.  



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Fig. Fig. 5: Removing the thermostat is simply a matter of removing the housing cap and pulling the thermostat up



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Fig. Fig. 6: Location of the thermostat on the 2.0L (VIN K and M) engines



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Fig. Fig. 7: Thermostat and housing mounting - 1994 2.0L (VIN 1) engine shown

To install:
  1. Install the thermostat in the housing, carefully pushing it down as far as it will go to make sure it's properly seated.
  2.  
  3. Install the housing cap on the engine.
  4.  

2.2L Engines
1987-91 VEHICLES

See Figure 8

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the cooling system to a level below the thermostat housing.
  4.  
  5. Detach the upper radiator hose from the thermostat housing.
  6.  
  7. Unfasten the thermostat housing mounting nuts, then remove the housing.
  8.  
  9. Remove the thermostat. Clean all gasket surfaces completely.
  10.  



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Fig. Fig. 8: Thermostat location and mounting - 1987-91 2.2L engines

To install:
  1. Apply a thin bead of sealer around the gasket contact surface of the housing, then install a new gasket.
  2.  
  3. Position the thermostat in the housing.
  4.  
  5. Install the thermostat housing on the engine and tighten the mounting nuts to 89 inch lbs. (10 Nm).
  6.  
  7. Attach the upper radiator hose to the thermostat housing.
  8.  
  9. Refill the cooling system.
  10.  
  11. Connect the negative battery cable, then start the engine and check for leaks.
  12.  

1992-94 VEHICLES

See Figure 9

  1. Disconnect the negative battery cable.
  2.  
  3. Properly drain and recover the coolant until the level is below the thermostat.
  4.  
  5. Unfasten the coolant outlet-to-inlet manifold attaching bolt and nut, then remove the outlet.
  6.  
  7. Remove the thermostat. Clean the inlet manifold and outlet mating surfaces.
  8.  



Click image to see an enlarged view

Fig. Fig. 9: After removing the coolant outlet, you can remove the thermostat - 1994 2.2L engine shown

To install:
  1. Place the thermostat in the inlet manifold.
  2.  
  3. Attach the coolant outlet to the inlet manifold, using the bolt and nut. Tighten to 89 inch lbs. (10 Nm).
  4.  
  5. Refill the engine cooling system.
  6.  
  7. Connect the negative battery cable, then start the engine and check for coolant leaks.
  8.  

2.8L and 3.1L Engines

See Figure 10

  1. Disconnect the negative battery cable.
  2.  
  3. Properly drain and recover the cooling system until the level is below the thermostat.
  4.  
  5. For the 3.1L engine, remove the air cleaner assembly.
  6.  
  7. Some models with cruise control have a vacuum modulator attached to the thermostat housing with a bracket. If your vehicle is equipped as such, remove the bracket from the housing.
  8.  
  9. Unfasten the coolant outlet-to-inlet manifold attaching bolt and nut, then remove the outlet and lift the thermostat out of the manifold. Clean the mating surfaces.
  10.  



Click image to see an enlarged view

Fig. Fig. 10: After unfastening the retaining bolts, remove the outlet and lift out the thermostat - 3.1L engine shown

To install:
  1. Position the thermostat in the inlet manifold.
  2.  
  3. Attach the coolant outlet to the inlet manifold. Coat the attaching nut and bolt with sealer, then tighten to 18 ft. lbs. (25 Nm).
  4.  
  5. If necessary, install the cruise control vacuum modulator bracket to the housing.
  6.  
  7. For the 3.1L engine, install the air cleaner assembly.
  8.  
  9. Refill the engine cooling system. On the 2.8L engine, use the vent plug on the thermostat housing.
  10.  
  11. Connect the negative battery cable. Start the engine, then check for coolant leaks and correct as required.
  12.  

 
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