[Public-list] Naive Diesel Questions

[Peter Staehling]

I have a good understanding of gasoline land based
engines with lots of hands on experience and some
experience with outboard engines.  Diesel engines are
a new thing for me to get my head around though so
please excuse the naive questions.

I am pretty sure that Aurora has a Yanmar 2GM20F.  I
was under the impression that she was direct seawater
cooled.  Apparently I was wrong.

Can anyone either recommend a good reference or help
me out with a basic understanding of how this cooling
system works?  I assume that there is a freshwater
portion of the system and a heat exchanger that has
seawater in the other side.  Where is the heat
exchanger located?

What implications do having a freshwater system have
on in water winter storage and cold weather use (I
like to sail on warmer days throughout the winter)?

Obviously I have to maintain the antifreeze levels in
the freshwater side.  The cap and overflow tank
locations are obvious and the owners manual for the
Yanmar is pretty clear on care of the freshwater
portion of the system.  It is less clear about the
seawater part.

Apparently the seawater part can be winterized by
disconnecting the hose from the seacock and placing it
in a container of antifreeze then running the engine
long enough to circulate the antifreeze (after
flushing with fresh water).  Does this need to need
done in this climate on a boat that will be run at
least once every month (and usually more often)?

Can I avoid having to charge the seawater side with
antifreeze each use?  It seems like the engine is well
below the waterline and would not get below freezing
in all but the most severe Chesapeake bay weather.  I
am guessing that a very small heat source would be
required in only the coldest times and that a light
bulb would be sufficient.  It could be turned on when
the forecast was for very cold weather or put on a
thermostat.

Is my reasoning sound here?  If so how much heat is
required?  What have others done?  Or am I the only
one  who uses their boat in the winter?  I really hope
this can be done with a minimum of hassle and a
minimum waste of antifreeze.

Pete #554

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