Cant figure this deal.Normally on my '92 F-150 w/302 auto..when engine gets up to normal temp,needle will stay around the N-O letters(cold side) of the NORMAL script on the temp guage.Now it has taken to fluctuating during driving,and it moves off the N-O toward the COLD side of the guage ...then back to N-O.What gives here?Thermostat maybe?Thanks for any ideas.

 

My 95 did the same thing and I checked the contact at the sender and the wire was a little rusted not making good contact. I cleaned the contact and it works correctly again. You might try that.

 

jakemarty90:hate to appear total dumba$$..but where is the sending unit?Thanks..Dave

 

On your 302 I'm not sure...maybe someone with a 302 will post. I'm running a 300 6. Good luck

 

Check the wiring, but it sounds like a thermostat that's stuck open.
A quick test is start the engine cold and hold your hand on the top rad hose it should stay the same tempature (cool to the touch) for the first 8 min at least if it starts to warm up before that, it's probably stuck open.
On the other hand if you have not changed it in the last 2-3 years just do it. (cheap insurance) P.S. let me know if you need more help.
Regards, Domenico...