Shut Down Procedure

ak-guy · Jun 15, 2019

I have a Yanmar 3 cylinder engine. The old Yanmar Operation manual gives the following shut down procedure:

1a) Place the clutch handle in the "neutral" position and
idle the engine for about 5 minutes.

1-b)
After five minutes' idling, place the speed control lever
in the "full" position and raise the rpms to about 3600 to
blow out any burnt gas in the cylinder.

I had never seen this before and have never done it. I have also never seen this anywhere else. Is it a good idea?

Xsbank · Jun 15, 2019

Not with a turbocharged engine, bad practice to spin the turbo fast then shut off its oil supply. It will continue spinning after shutdown. The rest is logical but idle speed as you approach your dock etc is plenty long enough for the temps to stabilize.

catalinajack · Jun 16, 2019

Xsbank said:
Not with a turbocharged engine, bad practice to spin the turbo fast then shut off its oil supply. It will continue spinning after shutdown. The rest is logical but idle speed as you approach your dock etc is plenty long enough for the temps to stabilize.

I have no idea on the best way to do this. But, so many commentators on this forum recommend following the manufacturer's recommendation. Why not on this question? What makes anyone here think they know more about a particular than the manufacturer?

Nomad Willy · Jun 16, 2019

I would ignore 1b and after complying w 1a shut the engine down.
Then call a Yanmar dealer and ask about the latter part of "1b".
I had a Yanmar 3 cyl 34hp "HM" for 6 yrs and remember no such thing.

Ski in NC · Jun 16, 2019

I have no idea why Yanmar recommended rev'ing to 3600 prior to shutdown. And yes, it is a bad idea if turbo (the Yanmar referenced is not turbo).

The way I do it is to get boat all tied up, which between no wake area and tying up involves about ten minutes of dead idle. Right before shutdown I rev it to about 1200 for about 10sec to get some oil thrown around, then to dead idle for about 5-10sec for turbo to spool down. Then shutdown. Probably completely unnecessary, but makes me feel better. Do the same with my turbo diesel car.

Nomad Willy · Jun 16, 2019

I hope it’s unnecessary as I’ve never done that.
I like the “oil thrown around” part though.

kapnd · Jun 18, 2019

I don’t see any advantage to revving before shutdown to throw oil around, the oil is already throwing around at idle speed and though it is probably throwing around at a lower pressure than when revved up, its all relative, as heat and friction increase with the revs too.

Shut Down Procedure

ak-guy

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Xsbank

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catalinajack

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Nomad Willy

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Ski in NC

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Nomad Willy

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kapnd

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