SR 20 thermostat housing

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   There may be subtle design flaw in the SR 20 engine (1991 NX 2000) which promotes failure upon thermostat replacement.  I have just experienced it.  Even with careful prep during torque-down the thermostat cover broke across one of the 3 cap screw holes.  Apprehension set in immediately of not finding this "antique part," but ebay is alive with several replacements sources  ($20 to $ 80).
The part is not ret received so the following is theory.  The apparent reason for breakage is due to slight shifting during installation of the new thermostat from its intended very shallow counter bore onto the flat surface reserved for the mating housing.  This causes the thermostat outer radius to create a high spot (should be flat when nestled properly) onto which the housing is torqued, snapping the casting. I intend to lock the thermostat into its C-bore with a thin coating of liquid gasket before mating and torque of the housing.

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motoman Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 3 hours 49 minutes ago Location: 98604 Status: Offline Points: 4	Post Options Post Reply Quote motoman Report Post Thanks(0) Quote Reply Topic: SR 20 thermostat housing Posted: 3 hours 24 minutes ago at 3:35pm
	There may be subtle design flaw in the SR 20 engine (1991 NX 2000) which promotes failure upon thermostat replacement. I have just experienced it. Even with careful prep during torque-down the thermostat cover broke across one of the 3 cap screw holes. Apprehension set in immediately of not finding this "antique part," but ebay is alive with several replacements sources ($20 to $ 80). The part is not ret received so the following is theory. The apparent reason for breakage is due to slight shifting during installation of the new thermostat from its intended very shallow counter bore onto the flat surface reserved for the mating housing. This causes the thermostat outer radius to create a high spot (should be flat when nestled properly) onto which the housing is torqued, snapping the casting. I intend to lock the thermostat into its C-bore with a thin coating of liquid gasket before mating and torque of the housing.