On my 1996 F-150 with the 4.9 L (300 CID) inline 6, for some time now, the engine barely reaches the normal coolant temperature as read on the gauge. Historically, it would climb until it was in a nice healthy spot in the middle of the gauge indicated normal range. About a year ago, I tried to fix this by replacing the thermostat, but the problem persists.
Assuming I correctly installed the new thermostat and it works correctly, I think the problem is either that the signal going to the gauge is bad or the gauge itself is the problem. The gauge is not cheap and probably tedious to replace so I'll assume the former case.
Given that, I have the following questions:
- am I correct in thinking that I should try replacing the coolant temperature sender?
- is there a good way to check if the thermostat is actually working correctly?
- am I correct in thinking that the temperature sender is the device that measures temperature and sends it to the gauge and that the temperature sensor is the device that measures temperature and sends it to the engine control unit?