Oil pressure oddities, is it the gauge or the engine?

[Ron Dame]

When I bought my Avanti last year, at 64,000 miles it had about 50 PSI on the road, hot, and about 30 at idle. Earlier this year, I noticed that the top pressure was about 40. I changed the oil and filter, and there was no change. Though I used  to have a mechanical gauge for testing, I had installed it in another car and no longer have it. The cost of a new one was about the same as a new pressure sender, so I did the obvious and replaced the sender with a new Stewart Warner unit, but there was no significant change. One thing I did notice ( I think that maybe it did it before, maybe not) was that the needle ticked up several PSI at a time instead of moving smoothly. Still I had adequate pressure, so I put it on the back burner.

I recently got a good buy on an NOS S/W gauge, thinking that maybe the needle was sticking. But there was only a modest change in pressure readings and no change in the needle action. As it is now, when I start, it takes a moment for the gauge to jump to 20, then in 5 lb increments to 35 cold idle.Then just starting to drive, it will jump to 42 PSI cold. Then I have the exact same pressures fully warmed up and the needle acts the same. As the pressure sender is such a pain to remove and replace, I'm hesitant to buy another mechanical gauge and see what it reads and how it acts.

Is this normal activity for a Stewart Warner gauge? Or is there something odd in the engine?

[ronmanfredi]

I had a similar problem, replaced the gauge using the same one from Summit Racing (best price) and ended up replacing the sending unit also to finally fix the problem.  I had an old distributor wrench that had an open end on it and used that to tighten then new sending unit.  An extended crows foot would work also.

 

[Ron Dame]

I like the crows foot idea. My dizzy wrench is a box end, so I don't think it would work. But I have a new sender and gauge ans still observe this.

[wildfelr]

RQB3263/81/305       HERE IS HOW I SOLVED THIS PROBLEM ONCE AND FOREVER, I HOPE

[Ron Dame]

That's a good idea!