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]
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.