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    Haibeck Automotive Technology

 

 

 

The heater hose quick connect fitting can cause the engine to run hot. The thermostat senses the temperature of the coolant from the return side of the heater core circuit. The connector also has the heater flow restrictor. The hole is about 5/16" and can become clogged. The connector in the picture is about 50% obstructed. A common source of material is the inner seal of the thermostat. When the thermostat gets very old the inner seal disintegrates and the fragments can accumulate in the heater flow restrictor. In addition to reducing heater performance the thermostat may require more time to sense the coolant temperature and open later than it should.

The connector sometimes corrodes and breaks off on the threaded end.

GM supplies the connector. They should have it for a long time because it is also used on trucks.