Oil pressure low at idle when warm

[PlayingWithTBI]

When I swapped flat tappet cam and lifters (not cam bearings) I gained ~10 PSI. Now it's at 20 PSI warm at idle, ~50 at 2000RPM+, with the Mobil1 extended mileage filter and 10W40.

 

[Andyvinn1]

I have replaced the rear main seal but didn't remove the bearing so hopefully didn't disturb anything with the oil path.
The AC-Delco is a paper filter, I'll be replacing it and cutting it open to see if i see any flakes or chips.

If the retrofit camshaft and lifters are new won't i get more metal material in the filter and oil do to the cam and lifters getting broken in?

 

[PlayingWithTBI]

If the retrofit camshaft and lifters are new won't i get more metal material in the filter and oil do to the cam and lifters getting broken in?

You shouldn't, especially with a roller cam. When breaking in a flat tappet cam you're work hardening it, not grinding it down.

 

[Andyvinn1]

When I swapped flat tappet cam and lifters (not cam bearings) I gained ~10 PSI. Now it's at 20 PSI warm at idle, ~50 at 2000RPM+, with the Mobil1 extended mileage filter and 10W40.

What RPM are you idling at. Before I did the swap i was getting 40psi at idle to 60psi at 2000rpm +. I'm about to adjust the throttle so i can idle closer to 1k RPM at idle while in gear with it being warmed up.

 

[Andyvinn1]

Yeah, probably going to bite the bullet and take it to a shop. Ran it in gear adjusted the throttle, idled at about 900RPM at 15 psi at the mechanical gauge. When i put it back on Park i was idling at 1300 RPM. Could be me being paranoid but the rocker arms were ticking. Also, at lower oil pressure i did see more blow back coming out of the valve cover filter.

 

[PlayingWithTBI]

What RPM are you idling at.

700 - 750 depending if I have the A/C on.

 

[Frank Enstein]

Thanks for the oil information, didn't know that's what the number stamp was. Using AC Delco filter PF-52. I don't know what the bearing clearance is off hand. I'll dig through my pile of paperwork to hopefully get the specifics.
Also, how much oil should I be getting out around the lifters? Would the lifters have anything to do with oil pressure?

You should have some oil coming out around the lifters. More than a seep but less than a squirt. it will ooze out but it shouldn't be a big deal.

 

[Schurkey]

Increasing idle speed to solve a low-oil-pressure-at-idle problem is no way to fix what's actually wrong.

It is a good way to beat-up the transmission, though. Gonna make for a more-harsh engagement of first, and reverse.

 

[Frank Enstein]

If the lifters are undersized or if the base circle on the cam is small enough to expose the oil band on the lifters that will drop oil pressure for sure.

If you remove the intake manifold and put an oil preluber (like this one that seals to the block https://www.summitracing.com/parts/sum-901015 ) in you can watch how much oil leaks around the lifters.

You will need to turn the engine over 2 complete revolutions.

Watch the oil pressure gauge to see if it drops at one point or another.

By the way your electric drill will work very hard and plot your violent demise if it gets too hot while you are prelubing so try not to melt it! Mixing paint and prelubing engines are the reasons I bought an air drill!

Watch to see that all the rockers get oil as the engine rotates. Not all of them will get oil at the same time.

 

[Schurkey]

By the way your electric drill will work very hard and plot your violent demise if it gets too hot while you are prelubing so try not to melt it! Mixing paint and prelubing engines are the reasons I bought an air drill!

Watch to see that all the rockers get oil as the engine rotates. Not all of them will get oil at the same time.

1/2" chuck, "500 rpm" air drill. The LAST thing a person needs is a drill that runs at 2K rpm like most 3/8 drills.

On Chevys or Pontiacs with a distributor, I just use a junk Points distributor with the teeth ground off the gear at the bottom, and a handle made from some brake tubing and a machine screw and nut. Turned by hand--about one and a half revolutions per second (90 rpm or so) is all that's needed to prime an engine after overhaul. "Priming" takes about thirty seconds. If you go more than a minute, you're doing it wrong.

Pontiac unit shown, Chevy similar

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Since you're doing an oil-leakage test, that's somewhat different from priming the pump. So a drill motor at low rpm might be required (or arms like canned hams) and substantially more time as you watch the oil flow around various parts--lifters, rockers, etc.