What Oil Pressure?

[Administrator]

At Shawn's request:

Tell us about your oil pressure at your favorite cruising speed when the engine is fully warmed up.

[MikeB.330]

50 psi on cold startup then after about an hour of running it drops to 40 psi at 1800 rpm and 20 psi at 700 -750 rpm in forward gear.

fresh water cooled and using heavy duty straight 30 weight oil

[roadnsky]

15-20 on cold startup at 700rpm.
Then 40 after the temp gets off the peg and it stays there at any rpm.
Cruise at 1700rpm. 5.5k in calm conditions. (40psi)(160º)
Castrol 10/30w

(Thanks for the idea Shawn)
-Jerry

[jhwelch]

Just under 60psi at startup.

Recently my engine has changed to a new steady state; now it takes 2 or 3
hours of hard running at 1,800 rpm for the oil pressure to drop down to just
a tad over 40.

20 at warmed up idle.

[sastanley]

ha, nice!

Ha ha..thanks, Bill!

You'll see why I was interested in this poll. I picked 20 psi, but it is often under that. I believe that I am fortunate not to have any of those fancy oil pressure dependent cut-off switches, or the thing would never run!

The oil pressure behavior is still somewhat of a mystery to me on my boat. When I first acquired her it seemed as long as the pressure gauge was above 'zero' I was supposed to be happy (this apparently was typical behavior reported by P.O. & I do not think he ever adjusted the pressure adjusting bolt) This was unsatisfactory to me, so before hauling, I turned it in one turn and saw a slight improvement, if I recall the ride to the travel lift it was 10-ish PSI. Over the winter I got another turn or so out of it, hoping for more PSI this spring.

I think I have just about run out of adjustment, after 2 or 2.5 turns in total (I got .5 more turns a few weeks ago and they seem to only turn together now, so I assume I've bottomed out on the adjustment.)

So, here is the current behavior. I always make my wife sit in the cockpit on the stbd side so her legs aren't blocking the gauge pod and I can see the gauges on the port side. I stare at them every couple of minutes! I am a gauge freak...

• Cold - first 5 seconds of running - 40 PSI - I've never seen it this high, except right at start up.

• After those 5 seconds of running it initially drops to 8-10 PSI

• Warming up - 10-15 PSI (15 at idle, goes down to 10 in gear)

• After extended running & warm up (30-45 minutes), it has been settling in around 20-25 PSI. I did see 35 one day at light cruise (1,400 RPM), but only once!

Type of oil is Mobil1 10w40, high mileage synthetic. This was the oil installed by the P.O., so for the over-the-winter change, I kept the same stuff. Now that I am getting the engine running a little better, I am probably going to experiment and go back to regular old SAE 30 and see how it does, unless you guys talk me out of it.

[Mark S]

I said 20 lbs, which is plus or minus where our pressure seems to be almost all the time, cold starting and at 1800 rpm, our usual cruising speed. The exception is when I drop the throttle to idle speed to slow down to pick up the mooring, when the pressure then falls to the low teens. When I mentioned this on the forum last fall, Don answered that many A4's run on low oil pressure and that Universal had said even pressure as low as 10 lbs. was sufficient. I'd like to see a bit more pressure at all speeds, say 30 at 1800 rpm and 20 or slightly less at idle.

Mark S

[jhwelch]

Shawn,

I met someone who had put one weight grade higher oil into his diesel which
caused some kind of sensor to trip out; he thought he was going to have to
pull his engine until he put the proper weight oil in, at which point everything
went back to normal.

So it's worth trying 30w oil. You'd have to go through 1 or 2 oil changes
to get most of the heavier oil out, so it's an experiment you'd be doing
over a bit of time I'd think.

-jonathan

[P30_889]

Oil Pressure

Yesterday I installed the new scavenger tube and started emptying the internal fuel tank. While I was there I couldn't help but start the engine again (I am like a kid now that the engine actually starts - I have to do it all the time.)

For the first time my oil pressure gauge actually moved! It started at 40, the engine rev'd up and when I lowered the RPM, the pressure dropped to about 20, then it slowly climbed back up to 40. So the gauge does actually move, but for some reason, the pressure stays pretty steady at 40.

[sastanley]

jonathon,

Thanks for the tip. I hadn't seen it until today. The oil has about 10 hours on it now, and it is clean as a whistle. I'll consider that, now that we are using the boat more....a 'couple' of changes with 30w is a lot cheaper than a 'couple' of changes with synthetic!

David,
Nice to hear the good news. I get all giggly when she fires up and runs too!
I finally stopped freaking out over the gauges today since we used the engine on 3 different occasions during our daysail. When it sounded good, I trusted it was running good. When I did sneak a peak at the gauges, I saw 155 F and about 25 PSI oil (@ 1,700 RPM, maybe 20 at sub-1,500). Those are GREAT numbers for my engine!

[rigspelt]

Spoke to another A4 owner who said their oil pressure was unvaryingly low until taking the sender out of the port, pumping a bit of oil through the port by bumping the engine, and cleaning out the sender. Then it read normally higher when cruising. They thought maybe a piece of grit had blocked the blind passage into the sender.

[joec43]

oil pressure

"Pot 'O' Gold" runs at 25 psi oil pressure when warmed up and running at cruising speed, when started cold higher at 35.

Joe

[Dave Neptune]

pressure

I cruise with my Indigo (the last 5) at 1900 rpm at 125 degrees with 35 psi of oil preassure, well just for the last 26 years or so.

Dave Neptune

[ne57301]

15-20 on cold startup at 700rpm.
Then 40 after the temp gets off the peg and it stays there at any rpm.
Cruise at 1700rpm. 5.5k in calm conditions. (40psi)(160º)
Castrol 10/30w

(Thanks for the idea Shawn)
-Jerry

Ditto on all - except about 6 knots in calm.

[lat 64]

Whiskeyjack is set a little high, 50 psi at cruise. I will most likely reduce it to 40 next month.

Shawn, are there any problems with synthetic oil in the clutch pack in the reversing gear?
Back in the day, the early synthetic manufactures said to not use it in motorcycles with wet clutch packs.

Russ

[sastanley]

Russ,
not sure...that is what was in the motor when I got the boat, so last year that is what I left in there. If you are wondering if I noticed any problems, the answer is, 'no'..everything seemed to perform as expected.

This season, I went back to regular dino juice - Rotella SAE 30.

The gauge is still low at start up , but seems to slowly rise to about 18-20 PSI after 40 minutes or so.