changing engine zincs on Cat 3126

M

merlin

Member
Jun 17, 2010
86
san francisco,ca/Marina del Ray, Ca
Boat Info
"Volare", a 2003 Sundancer 410, with original Raymarine electronics.
Engines
2, 350 hp, Cat 3126's
It's time to change the engine zincs on the cat 3126's on my Sea Ray 41. Is this something a novice can do or should I hire a service tech from Cat?
 
If you can unscrew a pipe plug, you can handle it.

However, if the zincs have not been changed recently, it is very likely that the anode will bind and unscrew from the plug or break off in the heat exchanger/oil cooler/aftercooler or riser. If it does you will have to fish the broken or dislodged anode out of the engine which may involve some disassembly that might exceed your skills. This alone is reason enough to service the zincs every 6 months on the Cats and every month on the Westerbeke, if you have a red generator.
 
Let me know when you are looking into it and I can come down, during the week, and point out all of the points for you. It is an easy maintenance item unless the zincs are broken off in the caps. I hope you had these changed when you had the boat serviced at the time of purchase. I would say in the bay you need to change at least twice a year.
 
fwebster said:
If you can unscrew a pipe plug, you can handle it.

However, if the zincs have not been changed recently, it is very likely that the anode will bind and unscrew from the plug or break off in the heat exchanger/oil cooler/aftercooler or riser. If it does you will have to fish the broken or dislodged anode out of the engine which may involve some disassembly that might exceed your skills. This alone is reason enough to service the zincs every 6 months on the Cats and every month on the Westerbeke, if you have a red generator.
Click to expand...

Seriously? Change the generator zincs every month?
 
Read your manual.............30 days.

I've found that to be a great trade off compared to removing the end plate on the heat exchanger (gasket and o-ring needed) and digging the zinc out enough to run a tap in the plug hole.
 
It must be very different being in warm salt water. I just changed mine (all zincs were done last spring) and they had anywhere from 50%-70% left on them. However, I'm in brackish water, most of the time.

Russ,
Being in LI Sound I would keep closer eye during the pick season as the water temps go up. Ask Mike and Dave on how often they change theirs, I think they have the same genny. They're in your area and it'll give you pretty good idea in regards to expectations.
 
Check with whomever you and Alex choose.........just remember this exchange when you have to go diving for zincs because you didn't believe the 30 days in the Westerbeke manual. Oh..........I forgot, the Westerbeke end caps are not flat but are convex, so go ahead and buy one with gaskets because you are not going to find one on the Sat afternoon you pick to change the generator zinc.
 
Frank, are you changing the zinc every month regardless what's left on it or is most of it gone by the end of 30 day cycle?
 
Yes...........what is left of the anode isn't material.

This particular heat exchanger tends to accumulate crud from the decaying zinc around the base of the anode. If you don't change it according to the recommended schedule, the anode will unscrew from the plug and you are stuck with a plug in one hand and the remaining zinc plugging up the hole so you cannot insert a new one. You then have to break down the heat exchanger end cap and fish out the anode. That makes a $1.00 anode pretty cheap. I have made a tool that fits into the threaded hole and screws on the anode to aid in pulling it out, but the success rate is only about 50% because the threaded end of the anode breaks off and I'm back to square 1. I just change them and keep on boating.

Also, I reload my own zincs by cleaning and installing new anodes on the brass plugs, so my cost is negligible.
 
I change mine about every 6 weeks.
 
I've got 11 zincs on each CAT and only 1 zinc on the Gen. engine to zinc ratio is very high compared to the CAT's. I run my Gen way more than my CAT's and I eat zincs on that sucker. Like Frank said, if you get a zinc stuck in there, the only way to get it out is to pop the heat exchanger cap off. That Gasket can only handle a few pop off's before it starts leaking. And the heat exchanger isn't cheap if you let it go and it starts eating your tubes. I buy them by the dozens at a time when I find them cheap(ish). I check it constantly and clean the hole every time I check it.
 
Mike, how often do you check/change zincs on your mains? Oh boy, 22 zincs...I hope at least the access to all of them is good. I got total 6 and 2 of them are a PITA.
 
The 11 per engine on these CAT engines are pretty easy to get to. I would say last time took about an hour to change all 22. The only issue is several tend to break off while unscrewing from the caps. Muriatic Acid overnight takes car of that though.
 
Caterpillar does a great job in planing for future maintenance. I can walk up to all of my zincs and only have to do 3 by feel. Its about a 15 minute job if you figure out that zincs are cheap and when you change them every 6 months, you don't go zinc diving.

Also, using acid will free the hole where you can insert a new zinc, but the remaining anode is then loose in the heat exchanger or cooler where it either eventually breaks up and passes thru in the exhaust or gets lodged in a tube where it stays and grows into a "corrosion flower" where several tubes get plugged. ONce again, zincs are cheap.......change them more frequently do avoid long term and more expensive issues.
 
Frank, I like your term "corrosion flower". I thought that in worst case if anode breaks off it will eventually dissolve. But you're right, there's a chance for it to become a "corrosion flower". So, it sounds like 6 months interval is pretty safe for the mains?

I think recharging the anodes yourself is the best way to do it, since some complete zincs come with anodes loose and require tighten them prior installation.
 
Well, true to my word I just picked up 22 zincs from Cat for $120 Canadian (don't say anything yet). 12 larger and 10 smaller. The nice folks at Cat even printed off the assembly views so I know where to find them. Of course on the 420Aft nothing is easy to get at unless it's on the inboard side! I was expecting a plug with the zinc attached but now I see I get zinc studs I understand what Frank was talking about. For a new guy: Do I remove the old and reattach the new using a pipe wrench or similar?

And the big question: Where do you guys get yours from at a reasonable price?
 
ktcanuck....boatzincs.com. Pipe wrench, no. You don't want to over-tighten these. Just use a small wrench and after they are tight, loosen them a hair. That way when you want to take them off you can tighten them a hair then loosen so they "break free" easier.
 
Just changed the zincs on the Cats last weekend. Three of the zincs broke at the neck of the annode. My buddy used a drill to get them out. He was able to drill into the zinc, and then pull it out on the end of the drill bit. I was surprised that the drill bit did not slip out of the zinc as he pulled it through the hole. On the one zinc that was especially stubborn, we drilled a hole into the zinc, and then screwed a long screw into the zinc and pulled on the screw to get it out.

I change my zincs once a year. Usually there is at least 50% and usually more of the zinc left. I find that changing them in the spring, before starting up the engines, is the time that the zincs are the hardest (because they have dried all winter), and are less likely to fall apart when taking them out.

As for the Westerbeke, again, I change the zinc once a year, and have not noticed excessive wear with that interval.

I get my zincs from boatzincs.com.
 
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