2008 ford fusion thermostat

where is the thermostat on a 2008 ford fusion with the 2.3L I-4 engine? if anyone has replaced one, how challenging was it?

They are usually located at the end of the top radiator hose, under the adapter where the hose connects to the engine. What makes you think you need to replace yours?

the check engine light is on. i had autozone put their code scanner on it and it read p0128, which is “low temperature”. and the temp gauge is moving around a lot, not significantly hotter than nomal, but sometimes rapidly moving towards cooler, then creeping back to normal again. i feel the error code is probably accurate, and not a faulty sensor because of what the temp gauge is telling me. where it appears the top radiator hose enters the engine is tucked tightly under the power steering pump in a very difficult to access area. i was hoping there is some other clever and easy to get to location for the thermostat where i hadn’t thought to look.

For about $20 you can pick up a Haynes or Chilton’s repair manual. It will give you the basic run down of the procedure.

I would also not make assumptions about the temp sending unit. It is easy to test with a multimeter. The resistance specs will also be in a repair manual. Your fan operation should also be checked. Varying temperature like that is not so characteristic of a bad thermostat.

Is the system full of coolant? Not just the overflow tank, the radiator too…Air in the cooling system can cause these problems…

i am eagerly awaiting the release of a hayne’s or chilton’s that covers this car. they’re not out yet.

this car has a coolant bleed valve, and a first for me - no radiator cap. i opened the bleed valve and added coolant to the overflow (per owners’ manual). any more coolant added would run out of the bleed valve. i don’t know how you could get any more coolant in there.

This doesn’t sound like a bad thermostat to me either. If the thermostat were bad, the engine would either overheat rapidly (stuck shut) or stay too cold all the time (stuck open). This kind of erratic temperature is most often caused by low coolant level or air in the system.

I am having the same issue. Get an infrared thermometer. Start it up and take alternating readings on the upper and lower radiator hoses. The upper should steadily increase in temperature and the lower should remain relatively constant until the thermostat opens at around 180 degrees. Then the lower hose, which goes to the thermostat should rapidly increase in temp. Mine was opening around 160 degrees so I will be changing it. It located behind the power steering pump. You need to remove the belt, pump and the coolant reservoir to get at it. Good luck.