I don't know about the exchanger on this engine, but yes, they are designed
to be opened and cleaned out. I did the job on my Yanmars a few years ago
and it solved a running hot problem. In this case there are caps on both
ends with gaskets and o-rings. Once they are removed, the core slides out
(one took a little tap with a soft mallet). Hose it down, and replace
gaskets and rings with new. The biggest part of the job was dealing with
the anti-freeze.

I also did an old Westerbeke years ago, dealing with the same zinc problem
you have. It was a different engine, but the same sort of thing, cap comes
off to expose the core. I just pulled out the zinc crumbs and stuck the cap
back on, but I kinda wish I had cleaned it out more. Perhaps someone can
explain if on the 4-107 the core slides out as easy as it does on the
Yanmar, and what gaskets one should have on hand.

"Paul C" wrote in message
ups.com...
I have a Westerbeke 4-107 in my new (to me) boat. Upon checking the
pencil zinc on the heat exchanger, I found that it was not screwed into
the cap, although I could see zinc sitting in the orifice. Either it
was coroded away in the cap, or was not screwed into the cap properly.
Not sure which, although the cap was clean with no zinc residue in it.
I tried to grab the zinc with pliers, but it would not come out.
Finally, it fell into the exchanger. The heat exchanger is a horizontal
cylinder about 3" in diameter and is about 14" long, with the zinc
fitting at the 9 o'clock position. My questions a Is having zinc
scraps sitting at the bottom of the exchanger a problem? The opposite
end of the exchanger is fitted with a bolt in the center. Is the
purpose of this bolt to an access to clean out the exchanger? If so,
how is cleaning accomplished. Thanks in advance for any responses.