Silly me. Since I bought my 1983 Landfall 35 a bit over 2 years ago, I had
been under the assumption since there was an "expansion tank" on the engine
that had coolant in it, that it was a fresh water cooled engine from the
factory. It is a Yanmar 3HM 30. No (F) on the engine tag. I had never
even bothered to look.. Yeah, the heat exchanger looked a bit different
from the one in the Yanmar manual, but since I'd been having a marina
commission and decommission my engine each year, changing water pump
impellers as necessary ("go ahead and do it"), I thought all was OK. I even
had a raw water pump changed out when the old one was demolished due to the
"cam" screw backing out and galling the inside of the pump. Turns out
there's more going on.
Low and behold, this year, when the mechanic looked around the engine, he
mentioned that it was the first time he'd ever seen a small diesel with not
one but two raw water pumps. As it turns out, the engine appears to have
had a fresh water conversion which was made by Sen-Dure, (thus the Sen-Dure
expansion tank/heat exchanger) and a second external pump running off a
belt. So one of the two coolant pumps is actually a circulation pump (the
one down low on the engine) and the other is a raw water pump..the one we
replaced last year.
Has anyone ever heard of C&C converting engines from Raw to Fresh at the
factory (Barry Carroll, Middletown RI built boat), or is it more likely an
owner conversion? My mechanic says that the rubber impeller on a raw water
pump will never hold up to the heat of the interior engine coolant and will
always burn up impellers prematurely if I keep things as they are. At one
point Yanmar made a fresh water conversion kit for 3HM engines, but very
unlikely there would be any availability considering the motor hasn't been
built since 1983.
This engine is somewhat dastardly in that it is installed backwards with a
V-Drive, making access to the "front" of the motor a really tough job.
Right now, I'm at a crossroads which involves:
a. Finding a suitable circulation pump that is up to the job for the
existing system, since I just de-scaled the heat exhchanger and bought a new
stainless mixing elbow
b. Finding the needed parts to do a Yanmar factory Fresh water
conversion
c. Keep the boat out of the water this year and save up to re-power.
Lavishing multiple thousands at a 36 year old diesel may not be the best way
to spend money.
Any suggestions would be welcome..
Chuck Gilchrest
S/V Half Magic
1983 Landfall 35
Padanaram, MA
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