Odd oil pressure problem


New Member
Mar 27, 2016
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Saratoga NY
I need some help with an oil pressure problem on my 318A engine.
Last week while priming my POLY with a drill and priming tool I initially got 50 lbs pressure but quickly dropped off to about 20 lbs then down to about 10 lbs. I also found I had very little oil to the top end. Gary Pavlovich spent an hour on the phone with me and we ran down some of the possibilities. We looked at the galley plug in the distributor area just above the cam gear and it was installed. But after running down a check list we determined that as some oil was getting up to the rocker shafts the oil galleys were open and I would probably be okay. Perhaps the drill I was using to prime the system just wasn't rotating at a high enough speed.
The engine has sat for 5 years after a complete rebuild, and new cam, while I built the car. Finally, I fired it up yesterday and found I had little to no oil pressure. Aside from the obvious chattering of the rockers there was no lower end noise and the engine ran smoothly. But showing no pressure I quickly shut it down.
Here are the particulars and I'm hoping someone can make sense of all the inconsistencies.

- Initially I installed an electric Autometer pressure gauge. Thinking the gauge may be faulty I installed a mechanical gauge. Started the engine and barely got 5 lbs pressure on the mechanical gauge.
- There seemed to be air pockets in the clear plastic tubing going to the gauge and not a steady stream of oil in the tube.
- I removed the oil filter and it was half full of oil. I filled it and reinstalled it. I had already replaced the oil filter plate gasket with a newer thicker gasket as the original gasket was leaking.
- Started the engine and no improvement.
- I pulled the distributor and intermediate shaft.
- Primed the engine with a drill and still very little pressure and still what looks like air in the gauge tube that move back and forth in the tube.
- Removed the tube from the gauge and primed the engine hoping to bleed the tube. Still have what looks like air pockets in the clear plastic tube and the oil just dripped from the tube into the cup I was using to catch the oil. No steady stream.
- Reinstalled the tube to the gauge and ran the drill. The oil pressure went up to 40 lbs but quickly dropped to about 20 lbs. Still saw air in the tube.
- Ran the drill for about a minute and kept about 20 lbs BUT the needle would fluctuate slightly - bounced between 20 and 25 lbs. Still there seems to be air in the tube that moves back and forth.
- I have not removed the valve covers to check for oil to the rockers.
- I have not reinstalled the distributor as I do not want to restart the engine to break in the cam and lifters until I get this figured out. Any and all thoughts are welcome and appreciated.
First, quit chasing your tail about the air in the gauge line. As long as there is some oil (showing it's flowing) in the line, pressure is pressure, doesn't matter if it's air mixed in with the oil or not. In fact, depending on where the gauge is positioned, you'll often see air in the line after years of running... Bleed back to the engine while sitting.

Next, 20-25 PSI on the drill is pretty good. I always turn the engine over by hand (if I have an extra set of hands) while priming just to get the oil to flow through the passages.

With the oil filter not full, it does take some time to fill and it takes some time to "prime" the oil pump from empty. It's my opinion that you didn't fill the filter with oil and you didn't run the drill long enough to pick up the oil in the pan and into the pump... then it didn't fill the oil filter. Since you shut it down almost immediately (and that's not a bad thing), the engine never had a chance to do this on its own.

I would say you are fine to restart.
▲▲▲▲▲▲▲ what John said. Plus also...
I'm not familiar with the poly engines at all but you may be sucking air somewhere along on the pickup tube side of things.
Don't worry about air in the gauge plastic tube every one I've come across had'em and read/worked fine.

The engine was built and sat for 5 years? THAT would tend to indicate that whatever cam lube that was put on the cam (especially if it was poured over the cam!) had all managed to flow off of the cam into the crankcase. MIGHT consider removing the intake and re-lubing the cam before you go any farther. Might also take the valve covers off and pour some oil over the valvetrain up there so they get some lube before use, too.

Didn't all Polys have mechanical lifters, too?

Even with a strong drill motor (industrial size), when the oil system pressurizes, the drill motor will take a big change in speed (slower), as I saw when a friend was doing that to his race motor.

Just some thoughts,
just a guess, does that oil pump have a pressure relief? maybe it popped off the first pressure spike and then failed to reseat itself and thus it is relieving your pressure.
Conclusion: My own fault.
With the help of a friend who knows these engine quite well we talked about where the oil could have gone and were able to piece together a quart here and a quart there, finally coming close to the 3 quarts missing from the engine.
In all the confusion of trying to get the engine running for the first time I did not replenish the oil that escaped from some of the repairs - replacing the oil filter housing, installing a second filter thinking the first one was bad, etc.
The lack of oil in the pan, plus the fact that the bottom of the pan was severely dented and pushing against the pickup, explains most, if not all, of my issues. The immediate 50 lbs of pressure that quickly dropped off to near zero pounds. The air in the gauge line.
Though I constantly checked the dipstick, which showed adequate oil in the pan, I failed to realize it was giving me a false reading. It was purchased as an exact replacement for the engine so I trusted the reading was correct. It was not. It was reading from a small amount of oil in the front of the pan, which I learned when I dropped the pan. With the pan out I was also able to tap it back into shape giving the proper clearance for the pickup.
This has taught me a valuable lesson. Slow down. Double check everything and trust (the vendor) but verify.
The upside is (along with being taken off suicide watch), I now know the pump and pickup are fine and properly installed. And with all your help I've learned quite a bit about this engine and its oiling system.
Buttoned everything up yesterday and now have a steady 70 lbs of pressure while priming, which I believe will go down some as the engine breaks in.
Thanks to all here who gave of their time and knowledge. So greatly appreciated.