Hi all,
I recently bought a 1970 F100 with a 390 in it and (among a few other things) the coolant temp. gauge doesn't work. I grounded the lead wire where it connects to the sending unit, and the needle moved, so I assumed the problem was with the sending unit. I picked up a new one at autozone for 10 bucks, but after replacing the sending unit, I am still getting zero reading from startup to shutdown. Do I need to somehow calibrate the new sending unit so it will register on my gauge? Or does anyone have any other thoughts? Thanks in advance
Zach

 

If it's on a extension like the small blocks, remove and clean to make sure passage is clear. Teflon tape used to "seal" the threads will also cause a problem. I figure if it actually had no oil pressure, you would have found out by now.

 

gfw1985,
Thanks for your suggestion. I realized (like the rookie that I am) when I logged back on that I had mixed up my sending units (I replaced the oil pressure sending unit and the coolant temperature unit at the same time), so I edited my above post to correct my mistake. It was actually the coolant temperature sending unit that the needle moved when grounded. The fact is though, neither of the gauges are working, even with the new sending units. I tried grounding the oil pressure unit and got nothing, so I'm thinking there's an issue with the wiring. The coolant gauge is the one that's throwing me for a loop though. Sorry for the mixup and thanks again for your input.

 

Did you ever get a response on this or a resolution?