Yes, heat exchanger (HX) zincs need to be replaced and it would seem frequently as there can be a lot of dissimilar metals in a HX. Catalinadirect.com carries all three sizes used on various Universal engines and they cost about $10 each.
Read this page: Catalina Direct: The Unknown Zinc
and buy all 3 sizes to start with and once you know what size yours takes buy a few of them. Give the ones that are the wrong size away.
HX = extra life on your engine + extra maintenance.
08-19-2010 08:39 PM
It's usually a pencil zinc, the size of a small screw on the underside of the exchanger. Get a teenager who doesn't smoke (they won't drop it, and then say.. wow man!) and offer them a prepaid phone card, pizza, or something else they may be into.
08-19-2010 08:11 PM
As hellosailor said, the shell and heads may be plastic but the tubes or other heat transfer surfaces will be copper or other similar metals. Plastic is a lousy conductor of heat!
08-19-2010 05:12 PM
Not offhand. I suspect you'd have to check local suppliers to see what they deal in, since freight tends to be steep on that kind of stuff.
08-19-2010 05:05 PM
The problem with zincs is getting to them. In my boat you have to be a contortionist to get to the HE zinc so it doesnt get changed enough. Do you know who manufactors them so I can research them?
08-19-2010 04:54 PM
Jeff, plastic just doesn't transfer heat well.
There are a number of heat exhangers and radiators built using plastic caps (top caps or end caps) but AFAIK the actual tubing is still going to be metal simply because it transfers heat SO much better.
With the right metals and an adequate zinc, corrosion should not be a problem.
08-19-2010 04:26 PM
Plastic heat exchanger
I am looking for any information on plastic heat exchangers. I saw in a picture what appeared to be one on a Bristol 32. I have a Bristol 32 with a Universal 5424. The concept seems to make a lot of sense. It would seem you would eliminate most of the corrosion potential in your raw water system that way. Does anyone have one, know of someone who does, or have info as to where you can find them?