C 85 Delayed Oil Pressure

[8360]

Here's a recent observation: Having watched for slow-to-rise pressure for months, I recently got a start, stumble, die on a cold engine. While prepping for next attempt (1-2 minutes to prime, etc.), the pressure rose slightly with engine idle, implying, of course, that the pump is making near-immediate pressure but gauge indication is delayed. I've tested this a few times since, and it is real. I have cleaned out the line to the gauge, but it is very small internal diameter and I didn't really "bleed" it. And I didn't check for residual oil in the gauge. Just adding to the discussion.

[6643]

The fitting in the engine case should have a small (~1/16") orifice, which can get clogged. Part of your process should be to remove and clean it.

[4004]

After doing what John C has suggested, then loosen line at gauge, to verify, and fill the line with light weight oil from the engine end ,as been suggested above, and then tighten the gauge end first and finally the engine. Sure sounds like you have air trapped in that line that has to be compressed before you get an accurate reading.

[VIP925]

I had been experiencing this until the copper line to pressure gauge was replaced with flexible hose during annual a couple years ago.
Now seeing oil pressure less than 20 seconds.

[8209]

UPDATE. Completed the annual, removed block fitting and lines connected to gauge. Cleaned everything out reinstalled, changed oil and filter, cut filter and inspected. Didn’t really find any obvious issues, but a half a dozen starts later cold and warm and I’m seeing pressure in less than 30 seconds. Good solid 40-45 psi after running. Hope it stays that way.
Thanks again for all the input.

[phil123]

Thanks for the update, had an issue with oil pressure last winter, it would slowly drop as oil warmed up and low at idle. This was a new problem that just started after the oil pan heater was plugged in one day. Turns out it was the oil pressure plunger not fully seating ( possibly from pan heater dislodging sludge? ) After removing oil pressure acorn style nut back R/H side of engine, cleaning and reinstalling it was back to normal pressures.