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eherlihy 06-04-2012 11:38 AM

Oil Scare - Universal M25
Shortly after she was hauled last fall, I changed the oil, and oil filter, and topped up the transmission with Dextron III ATF to keep the seals lubed over the long hard winter (that never came). The vessel is a '87 Oday 35 with a Universal M25, and a HBW 50 transmission. I had used Motorcraft 15W-40 Diesel oil, and a Fram PH-3593A Filter (I am not a fan of Fram filters, but had this on hand).
The Fram fits tightly under the alternator. Here is a pic with the Fram installed;

To start the season, I simply sucked the ATF (from the bottom of the xmission) down to the proper level, and should be good to go. Or, so I thought...

Because I also installed the new drive line and Engine mounts this past spring, I headded off Friday night for a "shake down" cruise to Cuttyhunk. The new drive line consisted of a new SS Prop Shaft, Cutlass Bearing, PSS Shaft seal, Coupling, 4 engine mounts, and dropped and reinstalled the rudder (which you have to do on the O'day in order to install the P-shaft.)

I could not align the coupling to the engine with feeler gauges, because, by design, the PSS Shaft seal pushes the coupling toward the engine, and the coupling had been machined with a lip that protrudes and fits snugly within the transmission coupling. This lip essentially forces the alignment of the coupling to the transmission, even wnen the bolts are loose. you can see the lip in this pic;
and here is a pic of the assembly;

However, the drive line seems good, as I can easily grab the stainless steel prop shaft and turn it in either direction by hand while the engine is in neutral. It is also 100% better than the alignment that was done by the PO.

We set off at 19:00 on Friday night, and because the wind was directly on the nose (isn't it always?), we motored for about 2 hrs. I was looking for any unusual noise or vibration, and was happy that tere was none. I was a little bothered that the engine would not reach full RPM at WOT. Instead of hitting 3000, it maxed out at about 2600. I may poke around with the alignment to see if I can address this.

However, after 2 hrs of motoring I was shocked to find that the oil pressure alarm had not gone off, but the gauge was reading just about 0 psi. This is a picture of the gauge, taken when the engine was off. The needle never dropped as low as this picture shows, but it did point at (maybe a little above) the 0 mark.

I did not want to be stranded at Cuttyhunk, so decided to curtail the trip, and headded back to port. The wind was now behind us :), so we shut down the motor and had a beautiful night sail back toward home port. When preparing to enter the channel to the marina, I started the engine, and carefully watched the gauge. The gauge was back up to ~30 psi at 2500 RPM. It's a long channel, so I continued to watch as the needle gradually fell to less than 25 PSI, and then, by the time we docked, was close to 0 PSI. Again, the pressure alarm NEVER went off.

My theory is that the multi-grade oil may have been of a lower viscosity than the container was marked. The next day I changed the oil and filter again, this time using a Bosch 3323 filter - which is narrower than the Fram, and fits like a dream under the new alternator and mounting bracket.

I also hypothesized that a dirty fuel filter may be causing the engine to be fuel starved at high RPMs. So, while I had my tools handy, and hands greasy, I also changed the fuel filters to a Parker R24P (30 micron) primary, and a WIX 33390 (10 micron "nominal" [whatever that means]:confused:).

I then ran the engine for over an hour as a test. The pressure level never dropped below 25PSI. However, I could still not rev the engine over 2600 RPM.


TQA 06-04-2012 12:23 PM

Re: Oil Scare - Universal M25
A defective oil pressure sender would be the first thing I would think of.

Zero oil pressure at 1500+ rpm for real would almost always indicate a serious problem and would usually be associated with some heavy knocking sounds.

eherlihy 06-04-2012 12:29 PM

Re: Oil Scare - Universal M25
I believe the sender IS working, as it does have a reading when the engine is cold, and when I rev the engine, what ever reading I have increases.

Fortunately no klack - klack noises; well other than the normal diesel sound. :)

Oaksail 06-04-2012 12:45 PM

Re: Oil Scare - Universal M25
I'm assuming your gauge is of the electrical type and not a direct pressure type.
Remove the sender and thread in a fitting, flexible hose and gauge and assess the pressure, a 0 to 100 psi gauge should work.
I had the same problem last year, turned out to be a sender wire grounding out at the back of the engine. 0 psi and the sender grounds itself to the block. The higher the pressure, the more resistance to being grounded.
Even though your gauge reads OK when cold your engine will vibrate differently when it is warmed up and cause the sender wire to ground out at a different vibration.

dabnis 06-04-2012 12:59 PM

Re: Oil Scare - Universal M25
What were the pressure readings last season? Did you use the same oil? What kind of filter did you use before? Possible situations:

1. Electric gauge sender going bad or poor connections? A mechanical gauge might be an option?

2. A filter that is plugged and the by-pass valve is not operating? As you changed filters and pressure stayed at 25 lbs the old filter may have been faulty?

Not reving over 2,600 RPM is likely another issue. Clean prop? Nothing caught underneath?
Plugged tank vent? Pickup tube screen partially plugged? Proper fuel filters? Fuel lines kinked or de-laminating inside?, on & on & on. Doubt that it is oil related but if so, likely something serious inside. Let us know how it comes out.

Paul T

dabnis 06-04-2012 01:38 PM

Re: Oil Scare - Universal M25
Forgot this, maybe someting crawled up inside the air intake tract and is partially blocking it?
Maybe old "bad" fuel? Both may be a stretch but worth considering?

Paul T

eherlihy 06-04-2012 01:41 PM

Re: Oil Scare - Universal M25
Same grade of oil (15W-40) different brand (Motorcraft, from WalMart). Electric gauge - but I believe that it is working. I think that the issue is that the oil was mis-labeled.

Also, forgot to mention that the Oil breather was blowing a fair amount of gas (air), and a little bit of oil out of the engine when the oil pressure was low, and RPMs high. This made me think excessive blow by - caused by the wrong grade of oil.

Also, also, I checked the oil pressure relief valve while I had the oil out of the crankcase, on the theory that it may have been stuck open - it wasn't.

Low RPMs is still a puzzle though. Great idea about the air restriction!!... I will definitely check that out on my next trip to the boat.

eherlihy 06-04-2012 01:44 PM

Re: Oil Scare - Universal M25
Prop was just polished and balanced and painted with transducer paint. It is possible that we picked up a line, but I doubt it. I will check anyway ASAP.

JimMcGee 06-04-2012 02:55 PM

Re: Oil Scare - Universal M25
I seem to remember reading about problems with the oil pressure relief valve on another site (may have been the C34 tech wiki at or on The problem was similar to yours but I can't find the link right now...

dabnis 06-04-2012 04:06 PM

Re: Oil Scare - Universal M25
Maybe just replace the engine oil pressure relief valve? Although when you changed to the Bosch oil filter you had a steady 25 lbs after an hour run? I remember on another thread some time ago someone had a similar problem and switching to the proper filter solved the problem. Not familiar with your particular engine but 25 lbs doesn't seem like a lot of pressure at higher engine speeds? If you have a shop manual it probably has the pressure specs in it. Blow by, is it noticeably more than last season? Any sudden change may mean
an "event" has taken place inside the engine. Hard to say how much is too much without seeing it or seeing how much liquid oil is coming out with it. Did the breather go back to "normal" after you re-changed the oil & filter? Overall, if you were running it hard with little or no oil pressure for very long it would be toast, but some damage could happen and the engine could still be running. A compression test may show ring, piston, or bore damage. Might be a good idea to try a mechanical gauge, at least temporarily, just to rule out any sender or connection problems.

Paul T

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