Automotive Systems

Formerly Automotive Systems I

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Thermostat

Thermostat

There are no repairs or adjustments to be made on the thermostat. The unit must be replaced when it fails to operate properly. A stuck thermostat can either cause engine overheating or overcooling.

If a thermostat is stuck closed, coolant will not circulate through the radiator. As a result, overheating could make the coolant boil.

When a thermostat is stuck open, too much coolant may circulate through the radiator and the engine may not reach proper operating temperature. The engine may run poorly for extended periods in cold weather. Engine efficiency (power, fuel mileage, and driveability) will be reduced.

The procedure for thermostat replacement is as follows:

  • To remove the thermostat, drain the coolant and remove the upper radiator hose from the engine.
  • Remove the retaining cap screws holding the thermostat housing to the engine. Tap the housing free with a rubber hammer. Lift off the housing and thermostat.
  • Scrape all of the old gasket material off the thermostat housing and sealing surface of the engine.
  • Make sure that the housing is not warped. Place it on a flat surface and check the gaps between the housing and the surface. If warped, file the surface flat. This action will prevent coolant leakage.
  • Make sure the temperature rating is correct. Then place the thermostat into the engine. Normally, the pointed end on the thermostat should face the radiator hose. The pellet chamber should face the inside of the engine.
  • Position the new gasket with approved sealer. Start the cap screws by hand. Then torque them to the manufacturer's specifications in an alternating pattern do not overtighten the housing bolts or warpage and or breakage may result. Most housings are made of soft aluminum or "pot metal."
Published by SweetHaven Publishing Services
Based upon a text provided by the U.S. Navy

Copyright 2001-2004 SweetHaven Publishing Services
All rights reserved