GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Thermostat

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REMOVAL & INSTALLATION



See Figures 1, 2, 3 and 4

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the radiator until the level is below the thermostat level (below the level of the intake manifold).
  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.

  1. Remove the attaching bolts and the water outlet elbow assembly from the engine. Remove the thermostat from inside the elbow.
  2.  
  3. Install new thermostat in the reverse order of removal, making sure the spring side is inserted into the elbow. Clean the gasket surfaces on the water outlet elbow and the intake manifold. Use a new gasket and RTV sealer when installing the elbow to the manifold. Refill the radiator to approximately 2 1 / 2 inches below the filler neck or, if there is a coolant recovery system, fill it up all the way.
  4.  



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Fig. Fig. 1: Thermostat installation; all models similar



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Fig. Fig. 2: Once the water outlet elbow has been removed, the thermostat can be removed as well



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Fig. Fig. 3: Always discard the old gasket and clean the mating surfaces



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Fig. Fig. 4: Be sure to install the thermostat in the proper direction

 
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