drop in oil pressure

[MikeB.330]

Guys,

For the past 600 or so hours after breakin my MM A4 has had perfect text book oil pressure. That is to say it's 50#s cold, 40#s hot at 1900 rpm (my cruise rpm) and 20# at idle in neutral. In gear at about 800 rpm she will hold just over 12-15 psi.

That's how it's been all the time, every time, that I've run the engine over the past couple of years since I set the oil pressure after break in.

Yesterday however, things changes. My cruise oil psi of 40 dropped to 20 psi and the idle psi dropped from 20 to 10. The last time I looked at the gauge before the psi drop it was holding 40# at 1900 rpm. The engine sounded and ran just as it should so I didn't really worry too much about it at the time. The total run time under load was under 2 hours

I've always been a gauge watcher for as long as I can remember.It must have been drilled into my head from my father who always looked at the temp waiting for the engine to overheat (same boat dif. engine). anyway,for whatever reason I tend to look over all the gauges about every 15-20 minutes. Not that I time it or anything but it just seems that I always have an eye on the gauges. I'm always telling people to move over so I can see the gauge so I know it's a regular thing


The oil has been changed every 50 hours using straight 30 weight oil. Last weekend I changed the oil on schedule using Shell Rotella 30w. heavy duty oil. This has been my oil of choice this year for the past 3 oil changes this year. Yep, I've put over 150 hours on her from spring to now.

The plugs are perfect, the oil level is fine and the engine doesn't burn oil.

I'm assume that for whatever reason that the regulating valve has decided to wig out. Tonight if the cold start up psi is way low, I'm going to pull the valve and have a little looksee.

I'm hoping that the ball (may have the neddle type) just jumped around a little bit and just needs a re-adjustment.

For those that have used it, what's your opinion of Indigos' regulating valve/filter kit. I don't care about the filter part, it's the regulationg that I'm interested in.

thanks guys.

Mike

one more thing. before the oil pressure drop the oil psi would jump up as soon as the engine would fire or rev up.. now, after the psi drop, the gauge is slow to respond. the pressure is slow to change but do follow the enging rpm.

[MikeB.330]

problem solved, for now

Removing and re-installing the pressure relief valve took care of the issue.
For whatever reason it went way out of adjustment. It was an early model valve so it wasn't a matter of the ball moving around. If it continues to be a problem I may try the Indigo oil filter system.




Mike

[sastanley]

Mike, I am plagued by low oil pressure too. It builds as the engine runs, but is around 8-10 PSI at idle, and barely follows Moyer's '10 psi per 1,000 rpm' rule. Tonight after about 2 hours of run time, I was elated it was up to about 32-33 psi at 2,000 RPM. It takes about 30 minutes for it to get above 20.

I cranked in my adjustment some this past winter to get the pressure to where it is now..when I acquired the boat, it was worse. I wonder if just yanking the regulator, cleaning, and re-installing would help mine too (late model with the ball as far as I know)

Oh, BTW - I am glad I am not the only gauge watcher in the group - 'honey...can you sit somewhere else? Your leg is blocking the oil pressure again'

[MikeB.330]

Shawn,

If You're having trouble keeping steady oil pressure and plan on removing and cleaning the valve, I would just go ahead and order an early model regulating valve first. The complete kit from Don is only $39 or you can use the Indigo kit for $80. Of course the Indigo kit has the remote filter and regulating valve. It would be one less thing to worry about.


for now I'm going to chaulk this up to a random thing that if it happens ever 500 hours or so I can live with. I would have no problem running 20 psi at cruise but I prefer 40 pounds..

I should add that after the regulating valve was re-installed the oil pressure followed the engine speed as it should (one warmed up)

[sastanley]

Mike, I am kinda waiting for something else to break to consolidate a little on my next Moyer order. I also want to get a few water pump parts..Baltimore Sailor's idea of having not only a spare impeller, but a complete shaft assembly ready to go sounds like a great idea to me. One less tool and less hassle if there is an impeller failure.

This could be enough of a list to warrant a call to Ken

So, what do you think about the bypass filter idea? Is it necessary? I have about 10-12 hours on the motor so far this year, and my oil (Mobil1 10w40) is still honey brown. I am also planning to go back to SAE30 oil on my next change. I only have 10w40 in there since that is what the P.O. had in it.

[MikeB.330]

Shawn
Unless you are not able to keep your oil pressure steady and spec, I would save the boat bucks and skip the Indigo filtration system. It would be a cool upgrade for sure but not one I would consider a must have item.

Change your oil every 50 hours with good quality straight 30 weight oil and you'll be fine. Every othe oil change put about 1/2 a quart of MMO in the crankcase about 1 hour before you change the oil. You will be amazed at how much junk will be picked up after an hour of running with the MMO in the oil. After you've run the engine for an hour or so with the MMO in the old oil, pump it out and replace it with 30 weight. Run the engine for another hour or so and then do another oil change. I do this every 3 oil changes or sometime every 4.

As for your idea to keep as spare shaft for the water pump, I wouls skip that too and go straight for a new pump. The new pumps do not have clips to hold the impeller on the shaft. They also do not need to be greased like the older pumps with the grease caps do. My reason for this is that the shaft seal on all the pumps (old and new style) are easily damaged. Once damaged they will begin to leak oil or coolant. With a new pump you can change the impeller in under 5 minutes without removing the shaft.

I think the new pump is like $275 and you will spend about $85 for a shaft, impeller, snap ring and gaskets. you'll have to decide for yourself if it's worth the extra cash to have an entire new pump.

[sastanley]

Mike...it sounds like what you are saying is that if/when I remove the shaft, I'd likely damage one of the seals anyway. Definitely something to ponder.

Good point on the oil system. Although predictable, the oil pressure is not what I'd call 'stable'. It is VERY low at startup (under 10 PSI), and slowly rises after the engine has warmed up. By the time I was done tooling around yesterday (see my other thread) I had 35 psi, but it took at least 30 minutes @ 2,000 RPM to get it there. I will also comment here that it is jumpy & the gauge reading flickers 4 -5 PSI randomly..I am hoping that is just the 30 year old gauge.

Do you think it would be worth it to do a couple of oil changes in the middle of the season & maybe remove & re-install the pressure regulator? Real dino juice is relatively affordable, so two or three changes with some MMO in there would be about $20. Sorry to hijack your thread with my issues.