Q: How to perform a thermostat replacement on Ford Excursion?
A: Check the coolant level, drivebelt tension, temperature gauge, or warning light circuit before changing the thermostat. If stuck open replace the thermostat if the engine takes long to warm up. When stuck shut replace the thermostat if the upper radiator hose stays cool and the engine runs hot. Overheating can lead to problems such as leaking gaskets, scuffed pistons, and warped/cracked heads. To drain the radiator, disconnect the upper hose, remove the housing bolts, and take out the thermostat then replace it after replacing O-ring ensuring proper orientation and a bleed hole position. With the housing repositioned tighten bolts, inspect the hose and clamp for any defect then reattach the hose followed by refilling of cooling system with coolant. Leaking should be checked once you start the engine to monitor its coolant level.