Hi, I have an issue with my oil pressure guage that has just occured. on Ignition the guage goes to full scale, when i start and run the engine it goes down to almost zero. It was okay last week, it has just happened and it has oil pressure. I replaced the sender unit on the block with no result. Any ideas??

 

I meant to say "Oil Pressure Gauge Issue"

 

Are you sure it isn't working? How do you know you have pressure?

 

What year car? It may matter..

 

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Is this based on the engine not knocking or did you install a mech. gauge(recommended)?

 

Hi, the engine is not knocking...just the guage reads very low. (1966)
The needle goes to full deflection (high) on ingition, when running it falls right back down to almost nothing. The mechanic said that he put a guage on the engine and oil pressure reading was okay, just the guage in the car doesnt reflect that

 

Go to Pep Boys, or any other big box automotive store, and get an oil pressure gauge, prefereably a mechanical one. It'll have a clear capillary tube. Hook it up and drive around with it to be sure the oil pressure is fine. Roughly, it should be about 15-20 at idle and maybe 40-60 running, all depending on engine condition.

There also could be 'crap' in the little tube going out to the sending unit, holding back the reading. You still haven't told us engine size or year.

 

Your 1966 dash gauge is all electrical - no tube to get crap stuck in on the way to the gauge. Having replaced the sending unit without any change, the only other element in the chain would be the gauge, itself. I've not experienced this problem, so that is just a guess. The constant voltage regulator could possibly be the culprit; however, since it also services the temp gauge and fuel gauge, you would see such movement in those gauges, also.
Best,
Al

 

Ok, I gave just bought a oil pressure gauge and it shows about 50 psi at idle. So oil pressure is good. Have replaced sender and gauge in car still not working. Time for gauge to come out I think