Chevrolet Full-size Cars 1968-1978 Repair Guide

Thermostat

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REMOVAL & INSTALLATION





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Fig. Fig. 1 When installing the new thermostat, make sure to install the spring side facing down, or away from the radiator



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Fig. Fig. 2 If equipped, mark and disconnect the vacuum lines on the thermal vacuum sensor



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Fig. Fig. 3 Remove the thermostat housing attaching bolts and remove the housing



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Fig. Fig. 4 Pull the thermostat free of the housing and ...



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Fig. Fig. 5 ... scrape the old gaskets off of the housing and intake manifold

  1. Disconnect the negative battery cable. Drain the radiator until the level is below the thermostat level (below the level of the intake manifold).
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CAUTION
When draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is 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. 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 in. 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 in. 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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