Chuck, It looks like the group has provided the relevant information. All I wanted to add was that “Ronin” came with a Yanmar 3HM (27 hp) that was sea-water cooled. After a very unfortunate set of circumstances involving information about the two thermostats, we had to have the entire upper end rebuilt. This would have been in the winter of 1998/99. We were able to convert the sea-water setup to a fresh-water cooling system using an OEM Yanmar heat exchanger. This did not require any addition raw-water pumps. Anyway, our new configuration is considered the 3HMF.
When we did this the mechanic made sure that we understood that we were getting the original Yanmar configuration and quality. And that we probably snagged the absolute last OEM fresh water heat exchanger out there… Were I in your shoes and planning on keeping your LF 35, I wouldn’t hesitate to move up to the new Yanmars. They are very impressive. I’d almost wish my engine were to go patas arriba in order to justify getting a new power plant. Best, Dave Godwin 1982 C&C 37 - Ronin Reedville - Chesapeake Bay Ronin’s Overdue Refit <http://roninrebuild.blogspot.com/> > On Apr 30, 2018, at 2:39 PM, Chuck Gilchrest via CnC-List > <cnc-list@cnc-list.com> wrote: > > 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: > 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 > Finding the needed parts to do a Yanmar factory Fresh water conversion > 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 > > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each and > every one is greatly appreciated. If you want to support the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray > <https://www.paypal.me/stumurray>
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