What's your oil PSI?

[Flyingmike]

What is your oil psi cold? Warm? Running hard? I have worried about my oil psi for some time. When the engine is cold it's about 50psi and after a few minutes of warm up settles around 40psi and if I push it hard will creep down to 25psi over the course of an hour. I took the boat to Catalina this week and had to motor the whole way there and half the way back. As the hours clicked by on motoring I noticed my temp slowly creeped up from about 140F to about 175F by the time I got there and my oil psi went down from about 40psi to 25psi as the engine gets warmer. Had the exact same as I came back. So I am wondering what are other people's psi? Btw I am using 10w-30, and have used 15w-40. With the same results. Early model engine. No thermostat, Moyer oil pressure regulating valve, not spring and ball. Should I simply turn up my oil pressure so it's ~65 cold, ~55 warm and ~40 running hard?

[romantic comedy]

cold it goes to 60
FWC 180 degrees at 2000 RPM it is 40 and stays that way no matter the running time.

I use 10w 30 or 10w 40 no particular brand

[Dave Neptune]

Mike, I motored over the 4th and my oil pressure is about the same as yours although I run at around 140 or just under.
Try a straight 30 wt or go the a 20~50 diesel grade and you should see about 5 more psi. The A-4 a 25 psi is just fine and will run happily so for years. I run straight 40 wt and have for many years now as my engine is now in it's 46th consecutive season.

BTW my boat just went up for sale, got to learn a bit more about stinkies now.

Dave Neptune

[Vermonstah]

Mike - excellent question, as I too am always curious as to whether my oil pressure is typical.

At start up, PSI is close to 50. After a few minutes to warm up, settles in at approximately 45 where it remains independent of load and throttle. For the past two years, I have been using the Shell Rotella 15W-40 Diesel Oil as recommended by several here on the forum.

My A4 is RWC, and now runs at 160 at cruise with a new Moyer water pump, climbs to 175 if I really push her.

In the 4+ years that I have owned the boat, I have never touched the oil pressure valve.

[joe_db]

I have found Rotella 15w-40 is easier to adjust the Indigo filter pressure setting for than other types of oil. YMMV
60 on cold start - falls to 40 - usually stays at 40.

[Hymodyne]

so far

Thus far, it starts cold around 80, then drops into the 40's.
But that is with just two pistons firing, if that makes a difference.
We'll see what it is tomorrow
James

[edwardc]

FWC, late model engine, with two-stage thermostat.
Once warmed up, runs rock-steady at 180.

Indigo oil filter with externally mounted pressure regulator.
Using Rotella 15W-40

When fired up cold, oil pressure starts close to 50, and quickly drops down to around 40 (at 2000 RPM).

After running for several hours, pressure is 35 @ 2000 RPM, 25 at 750 RPM (idle).

It was my understanding that the minimum oil pressure rule-of-thumb was 1 psi per every 100 RPM. This would seem to be consistent with the Oil Pressure Safety Switch (OPSS), which cuts off at around 5 psi.

[roadnsky]

Interesting...
My numbers are a bit the reverse of everyone else.
I start low when cool and then kick higher.

Cold is 20-25 PSI and once warm it jumps to 40 PSI religiously.
I used to use 30w for years and about a year ago went to Rotella 15W-40 (Diesel)

[JOHN COOKSON]

Interesting...
My numbers are a bit the reverse of everyone else.
I start low when cool and then kick higher.
Cold is 20-25 PSI and once warm it jumps to 40 PSI religiously.
I used to use 30w for years and about a year ago went to Rotella 15W-40 (Diesel)

Mechanical or electronic gauge? If electronic it is lying to you. OP decreases as the oil heats up and becomes thiner.
Some ideas: Confirm the readings with a mechanical gauge. Replace the sending unit. Be sure the gauge is not sticking.
If all else fails overhaul the OP adjuster.

TRUE GRIT

[roadnsky]

Mechanical or electronic gauge? If electronic it is lying to you. OP decreases as the oil heats up and becomes thiner.
Some ideas: Confirm the readings with a mechanical gauge. Replace the sending unit. Be sure the gauge is not sticking.
If all else fails overhaul the OP adjuster.

TRUE GRIT

My pressure has been like that since I first got the vessel.
It's not the gauge or sender.
Once she is warmed up, sits right at 40.
I have no concern. Just thought that it's funny mine is lower, then creeps up higher.

[thatch]

Actually we have seen and discussed Jerry's (his A4) condition before and it is not that unusual. Low oil pressure at cold start-up is most likely caused by a partially clogged oil pick-up screen or that not enough cold oil is getting through the oil pump 90 degree street L. As things warm up, oil flow increases, along with more pump flow, allowing the system pressure to build. Since we tend not to run our A-4s hard when they are cold, the important thing is to have decent oil pressure at motoring speed.
Tom

[roadnsky]

I'm inclined to agree with Tom's assessment.
Makes the most sense to me.
Turning the regulating valve only increases or decreases the pressure but doesn't change the low to higher readings.

AND, I always let her warm up.

[JDK]

I'm looking forward to seeing what my oil pressure does later now that iv thoroughly flushed out the rusty old beast and will be filling her with AMSOIL Synthetic marine oil, in 30 wt, as the design calls for......it will be interesting to see how she reacts to having proper film strength and shear stability and improved heat transferring action....

[Hymodyne]

running on all four cylinders now

oil pressure was as high as 80 when throttled up, but remained around 45- 50 at idle today when test run on the hard.

James

[thatch]

JDK and Hymodyne
Hi, oil types and oil pressure have been discussed here in the past and most of the outcome was really just speculation. However, if you don't mind I will give you my thoughts on these subjects. First, the use of synthetic oil

was innitially thought of as being too slippery for the forward gear clutch plates in our engines. I feel that the best answer to this theory is to change to synthetic oil and then to field test your engine, prop and hull configuration under a "high load" situation. In other words, if your transmission slips in forward gear, you may have to adjust it a notch or two to compensate for the more slippery oil. As far as oil pressure goes, it is recommended that you adjust your warmed up oil pressure to about 40 pounds and allow the idle pressure to fall where it may. These numbers are based on factory stats and I have had good results using them. Another factory stat that I really pay attention to is in the area of ignition advance. There is no other engine that I have ever worked on that treats ignition timing as casually as most A4 owners do.
Tom