Strange oil pressure gauge

[vinnio]

I have a mechanical oil pressure gauge in place of the broken stock one. Ive never had any problems with it before and it has always read right (I'm assuming...)

Last winter, I remember seeing about 90ish psi on cold starts (were talking up to -50*f or colder) Well, now its starting to cool down a bit up here and the gauge is really acting up, actually scaring me. The last few mornings have been in the 35* to 40* range. When I first start it, the gauge will go to its good old 90 - 95 psi range and sit for a while.

Here's the issue. When I start to move (slow at first) the gauge will drop to 10psi shoot to 50, go to 25 back to 90 and sit there for a while and do it again. I'm worried. It happens quick ( about 7 seconds for that scenario) Aside from my car chattering its teeth (lifter tick) I don't hear anything bad.

The oil was changed about 2k miles ago with 10w30. And it is full. I'm probably going to go buy a oil pressure test gauge and check with that, but until then.. any ideas would be great!

 

[Blurred Talon]

What brand of gauge?
Is it electronic sender? Possible sending unit going bad would be my first guess if so.

 

[BogusSVO]

Being that you have a mechanical oil pressure gauge

I bet you used the plastic tube that came with it, check that line very carefully for kinks, cracks.
Age, heat and vibration will cause the plastic tubing to fail.

Check around the fittings first.
A small crack in the plastic tubing will give funky gauge readings.
It will not take much, a pin hole is enough, and you may have a small oil leak.

I recomend that if you have the plastic tubing still, get some 1/8 copper tubing and replace it, the copper tubing will use all your same fittings that came supplied with the gauge.

Pick up some new crimp ferrels for the copper tubing

 

[vinnio]

SVO; Ill give that a look. I did use plastic tubing (a lot of it because its routed nicely) Its been there since the new engine. That's 4 years of 100* summers and -60* winters. Ill let ya know.

Thanks guys

Btw, is almost 100psi cold about right for these motors? It almost seems high to me.

 

[ed1380]

I'm guessing you don't have balance shafts. As long as it goes down within normal when its warm, there's nothing to worry about