Ford 1L2Z-8575-AA Thermostat Assembly

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Check the coolant level, drive belt tension, and temperature gauge before blaming the thermostat for cooling issues. If the engine warms up slowly or runs hot without a hot upper radiator hose, the thermostat may be stuck open or closed and need replacing. Don't drive without a thermostat as it affects emissions and fuel economy. To replace, disconnect the negative battery terminal, drain the cooling system, and remove the alternator harness bracket or engine trim cover. Find the thermostat housing by tracing the upper radiator hose to the engine, loosen the hose clamp, and remove the deteriorated hose if needed. Replace the thermostat housing cover if damaged. Remove the fasteners, detach the thermostat cover, remove the thermostat, clean off old gasket residue, fit a new gasket, and secure the thermostat housing cover, then refill the cooling system and start the engine. Let it reach normal temperature and check for leaks and proper functioning.

Before attributing a cooling system issue to the thermostat, check coolant level, drivebelt tension, and temperature gauge or light. If engine has prolonged warm-up times, replace thermostat. For engine overheating, assess upper radiator hose temperature. Cool hose suggests stuck-closed thermostat, hot hose suggests open thermostat. To replace, disconnect battery cable, remove air duct, drain cooling system. Locate thermostat housing, loosen hose clamp, detach hose. Remove housing cover, extract old thermostat, clean surfaces, install new thermostat with proper orientation. Reassemble, refill cooling system, start engine to check for leaks and verify thermostat functionality.

Feel the temperature of the upper radiator hose while the engine is hot. If it's not hot, the thermostat might be stuck closed.

Preliminary checks should include verifying the coolant level, drive belt tension, and temperature gauge operation.