Catalina 350 International Association

I bought hull # 368 this past Spring and was told the boat had been professionally maintained so I unwisely accepted this fact. Now in preperation for winterizing I found no zinc shaft on the external fitting (nut). Instead the zinc had broken off completely and is now jammed into the zinc cavity. Does anyone have any ideas for removing that zinc "plug"?? The HE itself is fairly clean and no leakage, cracks, deteriotation of either end cap so I don't want to remove the HE. Thanx, Jim - Lower Cheasapeake Bay, Deltaville, VA

Can you access it through the starboard end cap (will need gasket and O ring)? That would sure be the first thing I did.

That way all you need to do is shut off the raw water intake, not drain the whole engine coolant system (fresh water side) which you would have to do if you pull the heat exchanger.

Brett

Jim,

This has happened to me a couple of times where the plug unscrewed from a partially dissolved and slightly stuck zinc inside the hex. As I could see the threaded part of the zinc still there, I rescrewed the plug partially onto the zince without threading the socket and then wiggled it to pull the zinc out. Might work for you.

Russ Peel
Avalon #150

Brett & Russ - Thanx for your reply and info. I have already pulled the end cap from the HX so I am able to get to that zinc 'plug' from both the inside and outside of the HX tube. However I can't budge that plug and I can't get anyhting in there to pry it loose. I could probably drill it out but there is no way to get a drill bit in there with the Hx in the mounted position. And I don't think I could remove the HX enough to get a drill in there without disconnecting the hoses. I'll keep you posted. Thanx again, Jim

Take a short punch or make one from a bolt of slightly smaller diameter than the threads of the ZN. I know you don't have much room in there, but use a small hammer to "wrap" on the bolt to knock it lose.

Another option if you can get a small pair of needle nose pliers or small vice grips on the ZN is to work it out from the inside.

Brett

Can anyone tell me the part number and where to purchase a new zinc?

Was looking for a solution to a problem and find that I was posting on the same issue 4 years ago! Zinc anode expanded and jammed into holder on raw water side of heat exchanger. I tried Brett's suggestions but can't knock the residual material out so am about to remove hex and clean out throughly. It has only done 50 hours since a total rebuild so the amount of fouling something of a surprise. Tried to attach a small photo (129kb) but site won't accept it???

I've learned the hard way about the heat exchanger zincs. Here are a few tips. Firstly, many of the pencil zincs that fit into the brass cap nut are too long. They will reach the top of the heat exchanger and crack, and more than likely break off inside. The zincs I buy always need a 1/4 inch cut off with a hacksaw. Secondly, if the zinc has broken off, the remains (threaded part) can be removed quickly by drilling a small hole and then using an easy-out. If a broken part of the zinc is still in the heat exchanger, I've been told it will slowly dissolve, although I wouldn't want a collection in there, if you know what I mean. Lastly, I change my heat exchanger zinc 3 - 4 times a year.

I’m about to replace all cooling hoses and had a thought I would like members to comment on. The heat exchanger (HE) zinc is a bit of a pain to change since it’s in a blind spot and facing down. Since I’m having the HE serviced when I replace hoses and the HE mounting brackets are straps, I could rotate the HE 180 degrees in the horizontal axis so the zinc access is up instead of down. The new hose lengths and configuration would be different. But of course coolant in/out and sea water in/out hose connections would remain the same. Anyone see any reason this would not be a good idea.
Thnks for your comments
Rick Parish
Sea Breeze

Seabreeze - Interesting concept but I wold not do it. As you can see from other posts, the zinc pencil often breaks and it wold be more difficult to remove if rotated. Also, I think it might not remain in continuous contact with raw water in that position. I find it easiest to access from the rear of the engine when the panel under the bed is open.

You can not just rotate the heat exchanger-- the inlet and outlet dictate orientation.

The only way you could do it would be to remove the heat exchanger and weld a new fitting on the top for the ZN location. Expensive and IMO not a worthwhile idea.

Brett

We own a 2003 hull number “007”. I had some green corrosion growing on the inlet and outlet of my heat exchanger. Also, engine was running at about 178 degrees. I checked and the zinc had broken off inside. I think that the advice to trim some of the zinc off is well taken. In the future I am going to use a dental pic to measure depth for zincs on engine and generator. And then trim accordingly. I also found out that there is a salt water version of our heat exchanger. I decided against boiling out the old heat exchanger and bought a new one from Mr cool. I checked with a radiator shop around Punta Gorda and they do not guarantee the results. Also Russ at mr cool said mine has about 90 tubes in it. Russ thought reworking a heat exchanger is a waste of time. Of course he would say that. Russ owns Mr Cool.
http://www.mrcool.us/
2/1/2018 bought a new one.
201027CN Universal Heat Exchanger. This is number of salt water version. Russ says sea kamp makes them.
Processed Amount: $436.76. That amount included shipping. Russ the owner has the salt water version on sale for about $416. Hopefully, this heat exchanger, new thermostat, and impeller bring the temperature down a little. Also you can sale old heat exchanger for a few bucks.
Don’t forget to take the elbow fittings off the old exchanger to make connecting up hoses. I know I am repeating what everyone else already said.