I have a 350 small block in my 87 Z. I bought the car with 1,000 miles on the rebuilt motor. Since then I have put another 4,000 on it. I believe the block is a little older than the car and I am running fresh 10w30 in it. I'm told that I should move to a 10W40 due to the engine being bored over and that may help with a slight pressure rise.

What seems to happen is that once the car warms up and I find myself sitting at a stop light my oil pressure reads about 3lbs at idle. When I accelerate the pressure will rise once again. I did some reading up on it and decided to get a new oil pressure sender. I put it in yesterday afternoon and took it for a drive. Now when it warms up the gauge drops and reads 0 lbs at idle. The car seems to run fine and idles well.

I'd like to invest in some aftermarket gauges but at the same time keep my dash gauges functional............. For the time being I'm wondering what I can try next ?

 

I would get a mechanical guage to hook up. Dont drive the car with this on the inside. I've used them and let them sit up against the windshield wipers. I dont trust the factory guages at all.

 

If your oil pressure really was that low, your lifters would be clattering like hell..

like the guy above said, toss a mechanical gauge on it,and check then..

 

Would an electric gauge be fine ? My guess is that it would be much easier to tap into my new oil pressure senders electrical connector tab.

Thanks for your response.

 

No, you want to put a mechanical gauge directly onto an oil passage, and that will tell you what your oil pressure is at that point. If it is reading the same as the electrical gauge, then you need to find out why.

The reason we are saying to use the mechanical gauge is to eliminate a possible false reading, with your gauge, sender, and wiring as possible causes.

 

A mechanical guage eliminates all electrical as a possibility. Its usually more accurate. Then if you know you have good pressure, you can get a good electric guage. I run an electric autometer and it seems to be good.

 

coolhandluke937-
I was fearful for mine too, I did a t on my oil port where teh stock sender is on the top of the rear driver side, and installed a mechanical guage. When my stock guage shows 30 psi, the mechanical guage shows approx 55-60 psi. Just want to say, peace of mind is a great thing

 

I went out and picked up a mechanical gauge. I first ran only the mechanical and then used a " T " fitting off the block to incorporate both the electrical and mechanical gauges. I found that the mechanical gauge reads slightly higher when the engine is warming up (around 60 psi ) but once I reach operating temp I still get a reading of zero on the electrical and 2 on the mechanical. The vehicle idles at around 700rpm with those pressures. when I bring it up to 1000rpm it reads over 10lbs of pressure. The vehicle still seems to run normal. I also changed the oil to a 10W40 and that seemed to make no difference. I have always had a slight lifter tick since I bought it but it's not very loud.

Thanks for everyones replies
What is my next step ?

 

excessive bearing clearance, or a very worn oil pump..

i had a 406 that did the same thing, it spun a bearing shortly after..

if i were you, id start planning for a new oilpump/engine rebuild.

 

I'd have to agree.

 

I will start with an oil pump and hope that I can save it with that.