If you have a
perkins 4.108m lowline there is a pencil zinc in
heat exchanger that could cost you
money if not replaced regularly. I'm
posting this because its not listed in the 4.108m owners handbook(there's even a heading of electrolytic protection that doesn't mention it), the shop manual or many
boat manuals(including mine). I found it in the
parts number manual. Not finding it earlier cost me $350 for
heat exchanger. I asked about it earlier on cf and silence was deafening.