Heat exchanger zincs

[Jack Hutteball]

I changed my heat exchanger zinc today and it was gone except for a little residue which I cleaned out of the hole. I change it annually with usually around 50 hours on the engine.  It seems to be working.  As I replace the new one, I wrapped the threads with teflon tape to prevent leaks as I usually do.  I wondered if this tends to limit the protection by not having solid metal to metal contact.  Should it be replaced without the tape?  Tomorrow I get to have the usual fun of replacing oil and fuel filters!

Jack

[DEMERY]

I use to install mine using pipe dope. I then read on this board that it might limit its contact with the exchanger and reduce its effectiveness. It appears that the degree of deterioration over a period of time is the same with or without the pipe dope. It you can install it without the tape with no leaks, that would be my first choice. If it leaks, I would definitely use dope or tape. Like everything else related to boating, it's a degree of compromise.

Good Luck,

[Sailing Steve]

As long as there is some metal-to-metal contact so that the zinc is part of the circuit, that would be fine.  If you tape or dope the threads completely, the zinc may be insulated from the heat exchanger, which is not what you are seeking.  That being said, have a look at the cap of the zinc, as its face may make contact with the heat exchanger when it is screwed down, notwithstanding the threads being insulated.

Make sense?

[Ron Hill]

Jack : As we've said in the Mainsheet tech notes, on this message Board, in the FAQs and in Projects -- DO NOT PUT ANYTHING ON THE THREADS OF A ZINC!!!       Don't know how you missed it!!

Same goes for any other item that needs threaded contend to make it work.  If you have a M25XP the temperature sender and the oil pressure switch are 2 other items that come to mind that NEED metal to metal contact.   

[Mike and Joanne Stimmler]

Where can you buy the zincs? Do you have to get them from Catalina or are they a common item available from the local WM?

[Steve Hansen]

You can get the zincs at practically any marine store. Be careful of the length.
Steve

[captran]

West Marine has them, but I found alot of local placed both in Florida and Washington have the same thing at a few bucks cheaper than WM.  I do find I have to cut off about 1/2".