How to Replace the Thermostat in an '81 Corvette

The 1981 Chevy Corvette came with a 195-degree thermostat in a housing on the forward part of the intake manifold. It is easy to locate. The engine side of the top radiator hose is connected to the thermostat housing. The housing uses a rubber seal rather than a gasket. A thermostat can fail in either the open or closed position. If it fails in the closed position, the engine will overheat. If it fails in the open position, it will take a longer time for the engine to warm up and it may not reach the desired 195 degrees. This will provide very little heat in the cabin during winter.

Instructions

1

Raise the car and place jack stands under the frame on both sides of the car. Lower the car so it rests on the stands. Open the radiator cap. Place the drain pan under the petcock on the bottom of the radiator. Open the petcock and allow approximately a gallon of antifreeze to drain into the pan. Close the petcock. The idea is to drain just enough antifreeze to lower the level below the thermostat to prevent antifreeze loss when you remove it.

2

Lower the car to the ground. Use a screwdriver to loosen the clamp on the hose where it attaches to the thermostat housing. Pull the hose from the housing. Remove the two bolts holding the housing to the manifold using a socket and ratchet.

3

Lift the housing up and pull the thermostat out of the intake manifold and discard it. Remove the O-ring under the thermostat housing and replace it with the one accompanying the new thermostat.

4

Install the new thermostat spring end down in the opening in the intake manifold. Install the thermostat housing and tighten the bolts by snugging them down. Do not overtighten or the threads will strip in the intake manifold. The torque on these bolts requires a maximum of 30 foot-pounds. If the bolts are snugged down hard you can easily exceed this small torque.

5

Install the hose on the thermostat housing and tighten the hose clamp. Fill the radiator with the 50-50 mix of antifreeze and replace the cap.