Oil Pressure Issue

[1983Rampage]

Well, I am going off of a fresh build, I just wanted to let everybody know that to start with. But I went through and drove the car around to see how it handled and see how the engine was running. Well, I went for a good while and then after about 5 miles or so, the oil pressure started to go down, and after about 5 miles or another 15 minutes, the pressure was about completely down to about nothing.

I ended up getting home, thinking that I had some sort of an oil leak, but my oil was still full. The engine kept running so I know the oil pump was turning (BTW this is a 2.5l Turbo engine from a CB). And when I would keep the throttle going about 1500 RPM, the oil pressure would stay good to start, then after a while, it required more like 2500 RPM.

The first thing that came to mind was the oil filter? Maybe there was something that clogged it already? But I was wondering if there were any other ideas of what it may be.

The oil pump was a known good pump from a previous build. Any idea would be appreciated. Thanks

[puppet]

Check it with a mechanical gauge first just to be sure. A lot a different things can cause this.

[1983Rampage]

I just got a Mechanical gauge, and I will be checking the true oil pressure in the morning.

[R/Tony]

Quote:

Originally Posted by 1983Rampage I just got a Mechanical gauge, and I will be checking the true oil pressure in the morning.

Please update here the behaviour of the pressure! ... I just rebuilded my CB

[1983Rampage]

Alright, I got the gauge, and found that the gauge in the car is correct. (Which testing to see if it was right, which didn't have much of an issue, I ended up destroying a turbo) And I ended up dropping the oil pan, and the pickup was slightly clogged. So I cleaned it up, and put everything back together. I then put fresh oil in, and took it for a spin again, and the issue is still there. Any ideas?

I have also changed the oil filter 2 times, just in case, and that didn't fix much.

[moparfreak3]

Did you remove the balance shafts? If so did you block off the oil feed hole? Did you check the clearance on the bearings when you installed them? Excess bearing clearance can cause a loss of oil pressure. Also a couple other things that you need to think about is the pickup tube o-ring (if it is cut you will be sucking air instead of oil) and the mounting surface for the oil pump (if that surface is not flat you will loose oil pressure there as well.

[1983Rampage]

There are no balance shafts in the car, there aren't even the holes machined for them, the block is a 91 TBI 2.2l, so it does not have the balance shafts nor cross-drilling. So that couldn't be an issue. The bearings were good with good clearance. And there is a new o-ring on the pickup.

[1983Rampage]

Alright, well, I went through and looked at the shop manual again, and I may have found the problem. I really do not remember putting enough (if any) gasket or RTV on the oil pump to where it contacts the block. I will check it out tomorrow.

[puppet]

So, when you start the engine cold you have good oil pressure but after it's hot the pressure fades?
... or, on start up, either cold or hot, you have good pressure but it fades after running awhile?

I'm not too convinced that the missing sealer is too blame. I've put a couple pumps on with plain axle grease there and haven't had this (your) issue.

What oil and filter are you using BTW?

[1983Rampage]

When it is cold, it has pressure, but when it warms up, and after it is warm it slowly loses pressure. From start, warm or cold, it will have better oil pressure then after it has been running for a while. But I use Mobil oil and Fram oil filter. But I am going to swap out pumps and put on the sealant, since those are getting to be the last few areas that I could think of as being the problem.

[moparfreak3]

What kind of oil pump are you using? Melling, mopar, mopar performance? I use melling pumps on all my builds and have never had an issue.

[1983Rampage]

Stock pump, and I went through and swapped it out just now with a known good one and it is still having some issues with the oil pressure. Which the old one had some issues with starting to go bad, so I just swapped it to be safe and make sure it wasn't the problem. I have to run and do some stuff for now, but I am going to take a look at it again tonight. This is really starting to puzzle me as to what it could be.

[moparfreak3]

I would just get a replacement pump, prime the system and see if it goes away. I had this exact same problem when I got my 89 tona and when I put a new melling unit in it went away. And I have never put any sealer beween the block and pump either. If you want to put something there get some D.I.Y. gasket material I wouldn't use RTV just because you run the risk of getting some in the oiling system and that could get stuck in something you don't want it to.

[1983Rampage]

well, I ended up using a VERY little amount right around the very edge of the pump, and I will change out the filter again and see how it does. But if it does not go away, I will get a new pump.

[moparfreak3]

sounds good keep us posted