Does anyone know where it is. I'm new to this forum. I just inherited my Grandpa's 79 F-150 It has a 351M in it. I'm gonna start going through it. I just dropped the fuel tank on it cause it had been setting for over a year. I got it running pretty good but the temp gauge is not working. Anyone know or got any idea i'd appreciate it.

Nate

 

Is the thermostat good? That has been the problem on 2 of my late 70's fords i have purchased. As for the sending unit, i do not know, because the manifold is a dry setup on those, so i will not be on the manifold like the FE blocks.

 

Dont know for sure about 351's but take a look at the thermostadt housing. If there is a wire going to a connection there, it's probably the sending unit

 

It is just beside the thermostat housing .look for something brass with a a wire attached to it.

 

Generally on ford motors, the temp sending unit is in the intake manifold, usually center and towards the front near the water outlet and the thermostst housingon the left of the intake.then their is a wire that simply pushes on to the top of the sensor and runs to the insturment panel, so your problem could be in a bad temp sensor wich i would recomend replacing because it's cheap insurance, or your problem could be a bad gauge or corroded wire, i recomend just swapping out your temp sensor before digging into wires and tearing up your dash.

 

the sending unit is behind the alternater. its a little brass thing with a wire on the top

 

To check the wiring and the guage, you should be able to temporarily ground the temp wire and it should peg the guage (with key on). If this happens, then the wires and guage are operating correctly.

Marty