HX zinc replacement problem

[Earl Miller]

I tried to replace the HX zinc for the first time since I bought the boat in March and have run into a bit of a problem.  When the brass nut holding the zinc was removed there was no zinc residue in it.  I checked the hole in the HX and could feel the threaded end of the zinc still in position.  Apparently the cap came out but the zinc remained inside the HX.  Am I doing something wrong?
I screwed the cap back in ... hope the zinc is reattached.

[Jack Hutteball]

Earl,
I think that you will find if you take a wire or sharp object and push up on the zinc you will find that it is only a small piece of what is left of the zinc.  Most of it will come back out of the hole once you loosen it.  If it does happen to be the whole zinc you will have to remove the end cap on the HX and clean it out, which is described elsewhere on the website and also is a feature article on the technotes in the last mainsheet magazine.
Jack

[Mike and Joanne Stimmler]

I have a feeling that the last one who replaced the zinc used one that was too long and it either broke off or somehow got wedged in something inside so that when you un-screwed the plug, the zinc stayed in there. Unless you can grab it with something, you may have to remove the HX to see what's going on. I don't know if anyone has ever tried to run the engine with the plug out in order to force the old zinc out with water pressure but it might work. Just have a bucket or something ready to catch the water coming out and hopefully the zinc.

Mike

[Mike Vaccaro]

Earl,

If the old zinc is corroded, you should be able to break it up or push it out of the way by using a screwdriver.  The residue inside the heat exchanger won't cause any harm--you can then install a new one.  If the hole can't be unblocked, you'll need to remove the heat exchanger.  The zinc is easily accessed by removing the end cap of the heat exchanger.  Have found that in saltwater, the zinc will last about six months.  If you have a 3" exchanger, a standard zinc will fit without trimming.  Have had good luck with a small bead of Permatex type 2 (non-hardening) sealant toward the BOTTOM (about 60% below the top of the threads) of the zinc threads to allow good metal to metal contact. 

Best of luck,

Mike

[Earl Miller]

Just to finish off this thread ... I filed the outside threads off a spare cap and was able to screw it onto the jammed zinc.  With a bit of effort it worked loose and could be removed.  It looks like the PO put in a half inch zinc ... this will fit although it is basically the same diameter as the hole.  With any corrosion at all the zinc will stay in place when the cap is removed.  I replaced the zinc with a three eights diameter and everything seems to be fine.

[Mike and Joanne Stimmler]

Ouch!! I also used a 1/2 inch zinc when I replaced mine last month thinking I would get more protection and now I'm wondering if I'm going to have the same problem. Has anyone else used the 1/2 inch rather than the 3/8 inch zinc? And have you had problems? I measured the length but never considered the width problem.

Mike         

[Bob K]

On the subject of zinc replacement, here's something that might help you.  When I tried tom remove the zinc  for the first time just after purchasing my boat, the brass head would not turn.  Several attempts in various contorted positions using different types of wrenches all failed.   I ended up removing the HX - something I wanted to do anyway to clean/inspect and replace hoses.  At home on my work bench I had to give it everything I had to get that thing loosened.  After it was all back together, new zinc installed and tightened, and reinstalled on the boat, I checked for leaks after the engine came up to temperature.   A few drops were coming from the zinc area.  I tightened the zinc, but noticed it turned quite easily - it was notably looser than when I initially installed it.  Moral of the story......if it's stuck, run the motor first!!!!

[Ron Hill]

Guys : I believe that if your threaded "plug" will accept a 1/2" Zn then that's the correct size for your HX.  The 3/8" Zn has a smaller size "plug" and a 1/2" Zn won't/shouldn't fit in it. 
I'll recheck this the next time that I'm in WestMarine, but I do believe that's correct!! 

[Earl Miller]

Ron, the threaded plug takes either the 1/2 or the 3/8 zinc, the threads on the zinc are the same ... the difference is that the 1/2 inch is flush with the outside threads and leaves very little room for corrosion (white scale that builds up on the outside of the zinc).  What I found on the one I removed is that the zinc had dissipated where it was exposed to the water flow but the 1/4 inch or so that was next to the threads was still at the 1/2 inch size but with some scaling ... which caused the zinc to bind when I went to remove it (see picture).
Given the ease of replacing the zinc (thanks to the advice of the people on this web site) I will feel more comfortable using the 3/8 zinc and doing the job more often.

[Earl Miller]

the picture did not attach  on the previous reply ...

[Ron Hill]

Earl : You're correct that either a 3/8" or 1/2" will fit in either holder(plug).  Guess that you still have about the same amount of Zn if you cut off a 1/2" or use a complete 3/8" !!!
Good to know - Maybe I'll try a 3/8" next spring.