cannot figure out why my oil pressure gauge bounces around at idle and when driving. New rebuild 1000 miles ago, just replaced oil pump just to see if fixed, nothing in the drop screen. Gauge drops down to zero and bounces back up quickly, starts out around 50, then after warm hovers around 25 at idle. Cannot figure a consistent reason on why its dropping down to zero and bouncing back up.

 

Try another oil pressure gauge 1st to confirm it is not your gauge.

 

Ya try the gauge and be sure oil pump pickup is correct. You have a stock pan I assume. Dropping to zero is not good, seems like a lack of oil to the pickup for a moment. Otherwise your pressures are good.

 

Did you 'burp' the oil line going to the gauge? If not you may have air in it that is compressing causing the needle to fluctuate.

 

the air is compressed and it will not affect the reading. oil or air, pressure gauge reads the pressure not the amount of oil.

Is it a mechanical gauge? I had the same problem with my brand new Auto Meter electronic gauge, replaced it with a mechanical and no problems.

 

Not enough oil or gauge is what I'm thinking.

 

it is a mechanical gauge, and it is a stock pan. So I road tested it again today after installing new oil pump, and drop screen. Basically as I am driving between 2000 and 2500 rpms it sits around 25 as soon as you start to come to a stop and put in the clutch it drifts near zero, then as I am sitting there it goes back and stays at 25, then as I take off in 1st it climbs of course. I can replicate this process everytime I come to a stop, it never goes to zero when its driving or any other time other than when you coming to a stop??? Bizarre! Thanks for the help. I feel like the only way to really figure it out is to tear it down, but don't want to have to do that, but don't want it to seize up either.

 

we also did use a shop gauge and it did the same thing fluctuating but never showed up zero on that gauge got as low as 10, but when it was revved up it would bounce between 25 and 35 under steady throttle.

 

I'm wondering if the fittings on the line are over tightened?

 

I would try adding a half quart of oil or so and see what happens...