I’m currently working on the boat hobby and can address this when I get back 
later this afternoon. 3HM to 3HMF conversion....

Best,
Dave

Sent from my iPhone

> On Apr 30, 2018, at 15:26, svrebeccaleah via CnC-List <[email protected]> 
> wrote:
> 
>  Pegasus my old 38LF had been converted to fresh water cooling. Dont remember 
> who made the heat exchanger. It used the cam driven vane pump (old raw water 
> pump) as the recirculating pump. Replaced the impeller once in 10 years of 
> ownership. Yes access did suck. Never had an issue of that pump failing. Only 
> overheating issues I had was when the heat exchanger tubes became clogged. 
> My 39LF has the engine installed the right way (no vdrive) and good access to 
> everything except the dripless shaft packing. 
> 
> 
> 
> Doug Mountjoy 
> Rebecca Leah 
> LF39 
> Port Orchard YC, WA.
> 
> 
> 
> -------- Original message --------
> From: Chuck Gilchrest via CnC-List <[email protected]>
> Date: 4/30/18 11:39 (GMT-08:00)
> To: [email protected]
> Cc: Chuck Gilchrest <[email protected]>
> Subject: Stus-List Fresh Water Conversion Yanmar 3HM
> 
> 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
> 
>  
> 
>  
> 
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