My 72 Europa SS

[Sofa King]

Best case scenario is that the new oil pump I used was defective. If that isn’t it, I don’t have a clue what is causing the issue.

[BDA]

You might look at your bearings while you have it out.

[Sofa King]

I have to decide how far to dig into the engine. All of the rod and main bearings were replaced and the clearances checked when I put the engine together. The only ones I didn’t do were the cam bearings. Probably should have, but they didn’t show any wear. This was a used block that I bought for cheap! Previous owner said that it had spun a bearing but it hadn’t! Now I’m wondering what other damage could have made him think that was the problem.

[Certified Lotus]

Bummer! But best to repair now before you torpedo the engine due to lack of oil.

[Sofa King]

I absolutely agree! My concern is that finding the problem will probably exceed my abilities or experience. My “LS Engines for Dummies” book probably won’t provide the solution!

[BDA]

I wouldn't expect cam bearings to be the problem (although, I used to help a guy with his Ford 351 Cleveland race motor and the cam bearings were first in oil circuit and had to be restricted so the main and rod bearings would have enough so maybe it be an issue). After bearings, I guess you're pretty much left with the pump.

[Sofa King]

I have a friend that owns a shop and knows these engines pretty well. With out knowing much more than I’ve shared here, he also thinks it’s the pump. He didn’t think the cam bearings would be likely to cause the problem.
Because of how close I had to mount the engine to the firewall, I can’t change the pump without pulling the engine and transaxle. I really don’t want to put the engine back in with a new pump and still have the issue. But I think I just need to bite the bullet.

[jbcollier]

What is the oil pressure issue?  Low all the time?  Low just when it's hot?  Low as in the light is on?  Or, low pressure gauge reading?  If it is a low pressure reading, have you checked it against a known good gauge?

[EuropaTC]

To follow up on what John says, is this a mechanical or electrical pressure gauge ?  If electrical it might be worth checking the sender voltages or if possible swapping it out with a spare sender that you're certain is matched to the gauge.  I appreciate they don't often go wrong but I have had temperature senders give crazy readings before.

The other faint hope is the gauge itself as John mentioned. Without going back through all of the thread, have you previously had correct pressure readings on this gauge ?  If it's an unknown then before moving the engine I'd be tempted to make a temporary lash up with another gauge.

If all else fails then it might well be spanner time......

Brian

[Sandyman]

Sofa, fingers crossed it's the sending unit.

[Sofa King]

The problem is that, cold it has slightly low pressure, but acceptable. 25 psi on my electric gauge, about 35 on a mechanical gauge. I’m running both temporarily to see how accurate the dash gauge is.
When it gets up to operating temperature the mechanical gauge drops to 11-12psi at idle. This is with 20w50 to try to push up pressure. With 10w30 it was 7 psi and 0 on the electric!! The common diagnosis on an LS engine would be the pickup tube o-ring. I have had 3 different ones in, with the same results. I think another new pump is in my future! I’m just trying to decide if I want to give this short block another try, or replace it.

[Sofa King]

The oil pressure does increase with rpms, about 10 psi per thousand. This would probably be ok on a traditional small block Chevy but not great on mine.

[rjbaren]

I am coming in very late and this may and already have been stated as I didn't read through everything, but how about the oil pressure relief valve?  I rebuilt a Sunbeam alpine engine and it had nearly no oil pressure turned out the oil pressure relief valve was stuck.  Once the valve was freed up the pressure was what it was supposed to be. 

[jbcollier]

I'm not familiar with the LS engines but once saw a 454 in a new truck run on 5 psi at idle.  The dealer said it was fine, and, well, it was fine.  Still running last time I saw it.

+1 on the relief valve being stuck, especially on a recently overhauled engine.

[Clifton]

I'm not an LS guy either but 10 psi per 1000 rpm is good. Do LS engines need a lot of pressure?  Too bad if you have to pull it and go through it.