Hi everyone,

I need some advice from those of you who have run marine diesels for
several decades. We recently bought a Irwin Citation 38 which came with
a newly rebuilt Yanmar diesel engine. The engine starts and runs very
well as you would expect for an engine that has just been overhauled.
It also has a great paint job and looks pretty much like a new engine
with no rust showing anywhere, however...

In researching this engine--a Yanmar 3HM 27HP--it became apparent that
this series was only produced from 1980 to 1983 when it was replaced by
the 3GM30. In a car engine this would not cause me any angst, because
the block would have been being cooled by antifreeze and/or fresh water,
and the parts would still be readily available. In this case, it is a
23-26 year old marine diesel that was probably produced in limited
quantities, and--since it is raw water cooled--probably had salt water
sitting in the block for much of its life.

My options as I see them a

1) Do nothing and hope for the best. The engine will likely run well
for several years, and I may not need parts for it. Many parts (h20
pump, injector pump, injectors, etc) may be the same as on the 3GM30 and
quite availabe. Of course, that old block is getting thinner all the
time, and may not have nearly as much life left in it as it appears.

2) Convert the 3HM to fresh water cooling. This would stop the block
from deteriorating any further, and could stretch the life of this
engine into a decade or more.

3) Pull the 3HM and sell it. Replace it with either a rebuilt 3GM30, or
a new 3YM30. This is the most costly option both in terms of dollars,
and my time, but should result in the best long term reliability.

What do you think?

Don W.