Oil Pressure Guages

[Dixie Life]

OK, I give up. I can't find the problem with my OP gauges.* Both guages peg high when powered up.* With power off they read about 40; (0-80 guages). When eng. is rev'd to 1600 rpms the needle will drop from pegged to about 80 and when lowered to idle back to pegged again. I guessed both guages can't be bad so, I changed the sending unit. No change. I changed the lower guage with a new one; no change.* Took the orig. lower*guage an swapped it with the upper unit; no change.* The only thing I haven't done was change all the wiring. The guages are orig. GM type on a Lehman Ford 120 system.* What am I over looking?

 

[hogrider46]

I just had the same problem. I ended up changing both gauges and everything is back to normal. I guessed that one gauge shorted out and caused the problem but didnt go too deep to confirm. My gauges are electric.

 

[FF]

What am I over looking?


Installing much more reliable mechanical gauges !

 

[RickB]

Has this problem just shown up or has it always existed?

What kind of work was done just before the problem started?

Stick a meter on the sender after disconnecting the gauge wire and see if the resistance changes with oil pressure. Resistance should go down with increasing pressure.

Maybe the polarity is backwards on a meter or you are missing a ground.

Take your gauges down to the engine and wire one at a time directly to the sender with power coming from the hot terminal on the solenoid and see what each reads.

 

[Forkliftt]

The gauge needs a good ground, be sure it has it.