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From: Bob Clinkenbeard (no email)
Date: Wed Jan 05 2005 - 22:59:54 EST
I can't tell you where the thermostat is but I know that not all heat
exchangers have zincs installed. I am repairing one now off of my Perkins
6.354na. I have 4 tubes split due to the PO allowing it to freeze while in
storage. He would run the engine in his garage periodically to keep the
engine lubed and forgot to add antifreeze or drain the HE.
I know of others that have added pencil zincs to their exchangers by
drilling and tapping a hole in the end cap where it doesn't interfere with
the tube bundle inside.
If it were mine, I would rod out the HE tubes...you might not be able to see
restrictions. You said you have made sure the raw water is flowing
properly, also make sure the fresh water through the HE is unobstructed. By
then you will have eliminated the external plumbing and can focus on the
pumps and thermostat.
After all is said and done, installing a new impeller and recovering the
lost vane might just be the cure.
Good luck!
Bob Clinkenbeard
Custom Roughwater 41' Trawler
"Bobbin Along"
http://www.dreamwater.org/captainbob/
>I have a 1973 Gulfstar 41' ketch sailboat with a Perkins 4-108. It is
> overheating at medium or higher rpm. The engine was rebuilt
> (allegedly)about a year ago, just before i bought it. It was not really
> used last year [due to boat repairs keeping it dockside] except being
> turned over at the dock ~monthly.
>
> I removed the raw water thruhull and it has great flow. I removed and
> cleaned the raw water strainer (not even slightly clogged). I removed the
> raw water to exhaust hole and back-flushed all the way through the raw
> water strainer (last item before the thruhull - flow is great. I removed
> the raw water impeller cover and it seems fine though it has shed one
> rubber? 'tooth' - i will be replacing it.
>
> I opened the end of the heat exchanger (and located that missing impeller
> vane) - it didnt seem to have scale in there, but i didnt see any
> (obvious) sacrificial zincs.
>
> I suspect the thermostat has just enough scale to keep it closed, but cant
> locate it on this engine (though i found the one on my neighbor's 4-254
> easily). Can you tell me where the thermostat is located? And those
> sacrifical zincs?
>
> thanks!
>
> jim
> living aboard Nekkid Joy
> 1973 GS 41
> lying Charleston, SC - relocating to Melbourne, FL
> www.nekkidjoy.com
>
>
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