Day 46, APRIL 21 - Oil Pressure Crisis Over

[To cut to the chase, two days ago I came to the conclusion that the engine oil pressure problem was not real and that the real problem was a faulty oil pressure monitor. Today I ran the engine for 90 minutes with the oil pressure alarm on the entire time and saw no evidence of a problem with the engine. Details are below.]

I got up in the middle of the night, 1900, to find that the wind had backed 20 degrees not long after I had turned in for the night. I went topside determined to execute a gybe with no dramas, so I took no shortcuts. I rolled in half of the sail a bit at a time by alternating between easing the sheet and rolling the drum. Then I moved the airvane to let the Monitor make the turn and soon the small amount of headsail passed easily between the two forestays onto the starboard tack and I reversed the process and let out a bit of sail at a time. It was easy and no stress on the sail and I should do it this way all of the time. I had set the airvane well and we were now headed almost directly east. The night was only partly overcast because I could see a few stars and then wind was down to below 20 knots over a gentler sea. I pumped out the bilge with 50 strokes of the Whale Gusher then returned to the cabin for the rest of my sleep.

I was up at 0000, well after dawn, to find that the boat was still moving steadily to the E in front of a moderate wind and under a partly sunny sky. The house battery bank was at 12.4V which was excellent considering that I had not done a battery charging run since Day 41, April 16, 5 days earlier. Between the wind charger, solar panels, and the power economy measures, we were getting by ... which put an exquisite edge on the step that I was about to take.

----- The Engine -----

Over the previous two weeks I had been receiving information and advice on the engine oil pressure problem from several sources. I sifted through the various theories and advice about the possible nature of the problem and ranked them according to their probability.

I discounted the theory that the cause was due to polluted and diluted oil because the oil looked good (and as Reg wrote, 'if it looks good it probably is good') and the level was correct. (I discovered that the level was slightly elevated when checked with the engine cold and was normal immediately after an engine run, all due no doubt to whether or not the oil filter was full.) And I didn't think that there was much likelihood that the oil filter was clogged. It was a genuine Volvo filter, in use for only about 50 hours with oil the same age, and I couldn't take too seriously the possibility that either something had collapsed inside of the filter or something had become dislodged from the engine.

Then there was the intermittent nature of the problem. Mark said that the problem could be with the relief valves (whatever they are), but that such mechanical problems tend to be consistent, which made sense to me.

I had discounted the EVC panel which had been known misbehave before because those problems had been quickly resolved simply by powering the panel off then on.

That left the oil pressure monitor which was not being obstructed by anything but had an electrical component which sent an analogue voltage to the EVC. I agreed with Mark that electrical components can very easily exhibit intermittent problems.

But this left me only with a sort of residual evidence pointing to the monitor, not quite enough to hang my hat on

Fortunately Mark was able to give me the information that I needed. He directed me to a tube that passes from the adapter into which the oil pressure monitor is screwed to the top of the engine and passes into the front of the valve cover. This tube provides either the primary or secondary supply of oil to the valves. By backing off the nut at the valve cover I should get a flow of oil when the engine was running normally. The question was whether I would also get a flow of oil with the engine running during an oil pressure alarm.

Two days ago I got the 13mm wrench ready, slid back the engine cover, then went topside and started the engine and took it to 1000 rpm. I went back down below and put the snug fitting spanner vertically on the nut so that I could measure the arc of travel and backed it off 1/4 turn until I got enough oil seeping out to make me worry that if I backed the nut any more I would not be able to catch the oil with the paper towel that I was holding below the nut. I then snugged up the nut and stood back waiting for the oil pressure alarm. I didn't have a long wait because in the 6th minute the alarm went on and stayed on. I went topside to read the EVC panel to make sure that it was indeed the oil pressure alarm and then went back to the engine and backed the nut 1/4 turn. To my relief the same amount of oil as before seeped out.

If the oil pressure had dropped below the threshold 5 psi or so required to trigger the alarm I would not have expected the engine oil pressure to support a column of oil up to the valve cover and provide the same normal flow of oil.

After thinking about the issue for a while I decided that starting the engine and running it with the oil pressure alarm was worth the risk. The following day was too rough for the trial because I wanted to sit at the steering station during the entire run to monitor the EVC (in case I got a temperature alarm), listen closely to the engine for any sounds of distress, and keep an eye out for smoke in the exhaust. However I did disconnect the loud Cole Hersee buzzer which left only the quieter beeping alarm of the EVC.

This morning the conditions were right for the trial, with a calmer sea and enough wind to steer the boat, but I realized that I didn't really need to start up the engine for charging the batteries, so why risk the engine? I decided to proceed with the trial for several reasons. One reason was that I did not want to be forced to run the engine in adverse conditions at a later time. Another was that I wanted to resolve the question as soon as possible. Another was that I would be running the engine eventually, so I might as well do it now. I would run the engine eventually because I did not want to have to put the club to the trouble of towing me into the marina, possibly after a night's wait. And finally - here's the ego factor to distort rational decision making - I wanted to end this 5 year circumnavigation with a bang under my own power rather than a whimper at the end of a tow rope.

I dressed warmly, went topside with a big mug of coffee in hand, and started the engine. The oil pressure alarm came on immediately (gulp!). I then put it in forward gear, took it up to 1000 rpm, then sat back listening and watching. As the minutes passed with no evidence of distress from the engine I grew more confident. After one hour I moved the throttle to 1500 rpm. I later tried to go to a higher rpm but found that the propeller was overpowering the sail, so I had to satisfy myself with putting the engine in neutral then taking the rpms up to 2000 for the last 5 minutes of the 90 minute run. I then brought the throttle back and listened to the engine ticking over quietly at the idle speed of 750 rpm.

During the entire 90 minute run the engine ran as smoothly and quietly as ever and with the same clean exhaust as always, which I took as proof that the problem lay in the oil pressure monitor.

Afterwards the sun was out, a reliable moderate breeze was pushing us toward Frematle, and I was one happy little vegemite.

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At 0800 UTC the sailing day numbers were:

POS 37S16, 102E52
NND 120 nm
DMG 4142 nm
DTG 710 nm

The wind prospects for the next 2 days were good and I was looking forward to the 500 mile mark.

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