"Denny" wrote in message
oups.com...
If it ain't broke don't fix it!
Make sure there is a new anode on the engine and then run it until it
fails - or until you trade the boat off for a new one (which is far
more likely scenario)....

denny


Change BOTH anodes. Our engine 2-cyl has one in front where water enters
block and one at rear on cylinder head. The front one is easy to get at -
located on a splitter pipe where water from pump enters block. Rear one not
so easy to get at - located on cylinder head!

Not sure about the 3-cyl diesel, but our 2-cyl has a front plate on head
that serves as the alternator support and another plate at the back that has
the second anode and the temperature sensor. These plates can be removed and
this exposes the inside flow cavity of the head. Our engine had some scale
and rust build up just inside these plates - I scraped it away, but the
metal below looked pretty solid. If the engine has been rebuilt, one would
think that these plates would have been removed - It may be worth having a
look (at least at the front one) and seeing if the passages are clean
inside.

GBM

I've ordered a Yanmar service manual for the
engine. When it arrives, I'll start checking
anodes, etc. One thing I know for sure needs
changing is the fuel filter setup.

Don W.

GBM wrote:

"Denny" wrote in message
oups.com...

If it ain't broke don't fix it!
Make sure there is a new anode on the engine and then run it until it
fails - or until you trade the boat off for a new one (which is far
more likely scenario)....

denny



Change BOTH anodes. Our engine 2-cyl has one in front where water enters
block and one at rear on cylinder head. The front one is easy to get at -
located on a splitter pipe where water from pump enters block. Rear one not
so easy to get at - located on cylinder head!

Not sure about the 3-cyl diesel, but our 2-cyl has a front plate on head
that serves as the alternator support and another plate at the back that has
the second anode and the temperature sensor. These plates can be removed and
this exposes the inside flow cavity of the head. Our engine had some scale
and rust build up just inside these plates - I scraped it away, but the
metal below looked pretty solid. If the engine has been rebuilt, one would
think that these plates would have been removed - It may be worth having a
look (at least at the front one) and seeing if the passages are clean
inside.

GBM

I have the same engine in my 1983 C&C and it runs perfectly. Now I
have to admit mine is FW cooled but I really don't think internal
corrosion is likely to kill the engine. More like bearings and cam
wearing out.
If you compare the specs for the 3HM and the 3GM you will see the HM is
actually a heavier duty engine, greater displacement, horsepower, oil
capacity, etc. You are better off with a maybe rebuilt 3HM than with a
3GM that has definitely not been rebuilt. When sailing offshore you
are more likely to have your engine die from gunks stirred up in the
fuel tank than from anything going wrong with the engine.