Oil pressure very low; Pull the engine?

[geekeasy]

The oil pressure on my A4 used to be fine, but near the end of my last outing, I noticed it was it was very low. Now, when I start it at the dock the oil pressure shows up very low (~7lbs). If I give it some gas the pressure rises but not really over 15lbs. I've only run it long enough to check the pressure under these conditions.

A friend who knows more that I do about atomic 4s suggested that I pull the engine so that I can more easily work on it (with his help).

But pulling and reinstalling the engine is a huge amount of work that I'd prefer to avoid if possible. So at minimum I wanted a second opinion before I start removing the engine.

Should I remove it?

Or are there some other steps I should take first while the engine is still in the boat?

The engine is installed on an Ericson 29 which has great access to the top of the engine, okay access to the starboard side, but rather limited access to the port side of the engine.

Thanks for any advice!

[joe_db]

Get a second opinion before you remove the engine! (another gauge )

Also please note if the gauge is right, it may be the pressure control valve is stuck. Could be an easy fix.

[hanleyclifford]

By all means first attempt to adjust the pressure at regulator (port side of the engine). See page 5-3 in the Moyer Marine Service and Overhaul Manual.

[Loki9]

Did you check the oil level?

[geekeasy]

The oil level was fine, and the oil seemed okay (not frothy).

I just pulled out the valve, and it looked fine too.

So I guess the next step will be to remove the paint from the outside of it (the bolt is frozen in place with the paint), try tightening it up and see if the oil pressure goes back up.

[joe_db]

Did you check the gauge?

The oil level was fine, and the oil seemed okay (not frothy).

I just pulled out the valve, and it looked fine too.

So I guess the next step will be to remove the paint from the outside of it (the bolt is frozen in place with the paint), try tightening it up and see if the oil pressure goes back up.

[sastanley]

When you removed the oil pressure regulating valve, did you get the spring & ball out? bumping the starter (with a rag underneath the oil pressure valve) should ploop out the ball. Sometimes the spring distorts on itself, and sometimes gunk can get in the area where the ball seats and much up the works..

If you have an early style engine you'd have a plunger instead of steel ball.

I agree on the gauge too. Be sure all connections are good (sender, back of gauge, etc.) a loose connection will give errant readings...if all connections are good, I might try a 2nd mechanical gauge to confirm.

Pulling the engine for no other reason than a $30 gauge suddenly giving you different information than you are used to seeing is a bit drastic!

[Al Schober]

I second (third?) the check of actual pressure with a good mechanical gauge. Electrical gauges, particularly the sender, are subject to fault. The sender uses a fine resistance wire and a wiper to vary the resistance. The stuff that moves the wiper is the same as a mechanical gauge, but the wiper tends to wear out the wire as it's always rubbing in the same spot.
Unless you have a big strong friend to give you a 'dope slap', DO NOT pull the engine based on a low oil pressure reading from an electrical gauge (particularly one with some hours on it).

[geekeasy]

Fixed? Next step....

It took days to loosen the nut caked in layers of paint; meanwhile I noticed that the rubber gasket was falling apart.

Today, I tightened the adjustment and replaced the gasket which a temporary replacement from the hardware store.

Now... the engine reads 20lbs at idle. :-)

I gave it some gas in neutral and it climbed slowly up to 30lbs.

Thanks everyone! I'm sure glad I asked for a 2nd opinion before pulling the engine!

Next question -- is there any info online on how to adjust this valve correctly?

[hanleyclifford]

Sounds like you're already where you need to be - maybe just 1/4 turn clockwise to give you 40 psi at cruise rpm.

[67c&ccorv]

You need to get yourself a MMI shop manual.

[hanleyclifford]

You need to get yourself a MMI shop manual.

+1 on that; ownership of the MM manual raises you several levels above the average boatyard mechanic - and you get better from there.

[geekeasy]

I bought the manual and replaced my valve with possibly a worn out spring, with Moyer's recommend an old-style replacement valve. But now I'm having trouble with the oil pressure adjustment.

The biggest problem seems to be that the oil pressure behaves differently when the engine is under load.

I've got it adjusted now such that the oil pressure is at 20 when the engine is at idle. When I rev the engine in neutral the oil pressure climbs quickly up to 70+. But when I put the engine in gear (I can't do this too much at the dock), the oil pressure seems to stay lower than the desired 40.

Any advice on the next steps?

Do I have to keep taking the boat out of the dock on repeated test runs until I've got the adjustment right?

P.S. I'm not 100% sure this is happening, but if it is why would the oil pressure be higher revving in idle vs. under load?

[Loki9]

Do you trust the gauge? Is it a mechanical gauge or electric?

20psi at idle and 40psi at cruise sound good, so I'm not sure you have a problem (assuming those numbers are real). What reading you get reving and unloaded motor doesn't seem relevant to me.

Patient: "Doc, it hurts when I do this....."
Doctor: "Don't do that. "

[hanleyclifford]

That 70 psi reading is a little disturbing and suggests that the plunger is not moving freely in the passage. There may be an accumulation of foreign matter holding the cone.