Posted by: yachtanomaly | August 15, 2016

Engine Trouble- Part II

One of the things mentioned to me by all the pundits of diesel-dum, is that the reason the turbo seized was that I was not working it hard enough. You have to work a diesel hard, they like it – that is the belief (though there are many reasons not to believe). On a boat, the only way to work an engine hard is to run it at high RPM. There are no gears and you can’t drive it up a hill. I do not want to run the engine at high RPM all the time, the noise and fuel consumption go up geometrically. But at least run it hard for a few minutes periodically I was told. So we began to do this, every few days running it faster for a few minutes.

Approaching Tofino, it seemed like a good time so I ran at 2500 rpm (close to 8 knots speed) for 10 minutes. Just as the 10 minutes was nearly over, alarms went off and the indication was “low oil pressure”. This is not a good thing. I shut the engine off immediately, and we drifted to the side of the channel. Low oil pressure can be caused by several things, the worst being a spun bearing, requiring a major rebuild. Or it could be low oil level, or oil thinned by heat or contamination, or whipped into foam. I checked the oil level, it was at the middle of the dipstick as it had been all trip. There were some bubbles on the dipstick which could be an indication of foaming – perhaps. The engine compartment also seemed very warm, I had never checked this “running hard” because I never ran it hard before. So – there was enough oil, perhaps it was too hot, perhaps it was foamed, or perhaps the oil pressure reading was false? Or was the engine destroyed?
I turned on the engine room blower to cool it down, fetched the IR heat gun from below, and removed the engine compartment side cover. There was just 3 knots of wind from aft, enough to steer the boat down the edge of the mudflat we were next to. The oil filter and pan measured at about 195 degrees, this makes sense as that is the temperature the engine always runs. In short there appeared to be nothing wrong. After allowing it to cool for a few minutes, I restarted the engine, which idled normally and no alarms or other noises. Put in gear, it seemed to drive the boat the same as always. We motored into Tofino.

Further investigation revealed nothing at all. The oil seemed normal in viscosity and color, there was no indication of anything amiss. I began to suspect that the engine compartment had gotten hot enough to cause problems. At the only hardware store in Tofino, I found an indoor/outdoor thermometer and placed the outdoor sensor (which is wireless) in the engine compartment directly above the engine. I had never measured this, only stuck my head in the door to confirm that it is a little warm in there, but an engine compartment is going to be warm. We motored to Ucluelet with 2 – 4 knots SE wind (forecast 20 – 30 NW – but that is another story). At our normal motoring speed, the temperature slowly climbed to 118 degrees – that is warm, but not too warm? But this day was 65 degrees, not 85 like yesterday, and the engine putting out only 20 HP, not perhaps 50 “running it hard”, and therefore less than half the heat. A conclusion from this is that the compartment probably should have a ventilating fan to supplement the vents that it does have. Definitely if it is going to be “run hard”.

There remains no good explanation for the warning and shut down. One theory is that the oil pressure is sensed by an electronic box mounted on the engine, this result is sent via the NMEA 2000 network to the chart plotters and other instrument displays, which sound the alarm. The maximum temperature for this box is specified to be 158 degrees, could it have gotten too hot and alarmed in error? We had “run it hard” several times this summer already, though not perhaps quite as long or on so hot a day. Hot electronics will cool off and work again, a destroyed engine does not self repair. Foamed oil might recover, contaminated oil will not.
Just another mystery to contemplate in the paradise of sailboat cruising.

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Responses

  1. Enjoying your comments as I drive along with Helen-Anne between Virginia and SMU in Dallas!


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