GM Full-Size Trucks 1980-1987 Repair Guide

Thermostat

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REMOVAL & INSTALLATION



  1. Drain the radiator until the coolant level is below the thermostat level (below the level of the intake manifold).
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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 water outlet elbow assembly from the engine. Remove the thermostat from inside the elbow.
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  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 when installing the elbow to the manifold. On later models the thermostat housing may have been sealed with RTV sealant. If so, place a 1 /8 inch bead of RTV sealer all around the thermostat housing sealing surface on the intake manifold and install the housing while it is still wet. Refill the radiator to approximately 2 1 /2 inch below the filler neck.
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If the thermostat is equipped with a pin hole, be sure to install pin side facing upwards.

 
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