GM: Electra/Park Avenue/Ninety-Eight 1990-1993

Thermostat

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Fig. Fig. 1 Thermostat and its housing

The thermostat is used to control the flow of engine coolant. When the engine is cold, the thermostat is closed to prevent coolant from circulating and cooling off. As the engine begins to warm up, the thermostat opens to allow the coolant to flow through the radiator and maintain the engine at its normal operating temperature. Fuel economy and engine durability are increased when the engine is operated at normal operating temperature.

REMOVAL & INSTALLATION




CAUTION
Never open the cooling system when the engine is hot. The system is under pressure and will release scalding hot coolant and steam which can cause severe burns and other bodily harm. 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.

  1. Drain about a 1 / 2 gallon of engine coolant from the radiator. Disconnect the negative battery cable.
  2.  
  3. Remove the radiator hose from the water outlet.
  4.  
  5. Remove the water outlet attaching bolts and the water outlet.
  6.  
  7. Remove the O-ring (vin C), gasket, and thermostat.
  8.  
  9. Clean the manifold water inlet and water outlet mating surfaces.
  10.  

To install:

  1. Position the thermostat into the intake manifold with a new gasket and O-ring if equipped.
  2.  
  3. Install the water outlet to the intake manifold. Torque the attaching bolts to 20 ft. lbs. (27 Nm).
  4.  
  5. Install the radiator hose to the water outlet housing.
  6.  
  7. Refill the engine with the specified engine coolant. Connect the negative battery cable, start the engine and check for coolant leaks.
  8.  

COOLING SYSTEM BLEEDING



To ensure complete filling of the cooling system, it is necessary to bleed the system.

  1. Disconnect the negative battery cable.
  2.  
  3. Park vehicle on level surface.
  4.  
  5. Remove thermostat housing cap and thermostat or open bleed vent on thermostat housing. Open 2-3 turns.
  6.  
  7. Fill cooling system with coolant to base of radiator neck.
  8.  
  9. Reinstall or replace the thermostat and housing and close air vents.
  10.  
  11. Fill the coolant reservoir to proper level with a 50/50 blend of ethylene glycol and water.
  12.  
  13. Reconnect the negative battery cable. Start the vehicle and let the engine reach operating temperature adding coolant as needed. Check the cooling system for leaks and make sure the cooling fan comes on when needed.
  14.  

 
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