Follow the upper rad hose and at the engine is the housing that houses the thermostat. When replacing it make sure the spring goes toward the engine.
Find the thermostat at the engine end of the upper rad hose. When you replace it , make sure the spring goes toward the engine.
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at the top of water pump in separate housing
forward of the firewall
This is a 15 year old vehicle. The thermostat is very cheap insurance. Just replace it when performing a cooling system service. Replace it by removing the old thermostat, carefully cleaning off the old gasket. Install the new gasket & thermostat, spring toward engine block, and tighten to factory specs, and no more.
it is located and accessible under the dash by the front passenger floor board. need 8mm nut driver only. easy
should be located by the thermostat housing on front of engine block
Temperature Gauge Sending Unit The sending unit is located in the front section of the intake manifold in the vicinity of the thermostat. Change it.
some possibilities are. low coolant level, open thermostat, pluged heater core,
Its in the fuse box under the stearing wheel.
on a 1993 4.9 it is just to the left of the thermostat where the radiator hose and heater core hoses go into the thermostat it has a couple of wires running into it.
The 1999 F150 4.2 does not have a temperature sensor. It uses a cylinder head temperature sensor instead. It is mounted at the rear of the engine on the head.