Replacement of Engine Zincs

Four Suns

Four Suns

Not a pot stirrer
TECHNICAL Contributor
Oct 4, 2006
10,533
Williamsburg, VA
Boat Info
2003 480 DB
Engines
QSM-11 Diesels
I was out last night pulling that transmission cooler off that had the bad hose during our trip this year. The bracket needs some love (sanding and painting) and I'm putting new rubber o-rings on the thing. Anyway, I also started some maintenance after the big trip like zincs, strainers, etc.

So here's a picture of the engine zincs that were put on less than 3 months ago:

db5d9821.jpg


I post this because I've seen a few posts of people saying they only look at the zincs once a year up in those waters... Maybe it's a Cummins thing or an electrical cord thing but they sure got chewed up fast. I usually change mine about every 4 months but those things don't have another month left in them.
 
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Saw the same with our engine zincs. They were replaced when we slipped her in saltwater 2+ months ago. I checked them this past weekend and they look just like yours do. 2+ years prior in fresh water they had little wear on them.
 
WOW....I never replaced the engine zincs in any of the 7.4s that I've owned....Heck...I didn't even know they had engine zincs.....
 
We have San Juan Full System Fresh Water Cooling Kits on ours...the zincs I referred to above are in the heat exchangers.
 
I'm resurecting this thread because in 'keeping engine happy' thread. it was mentioned that when the engine sits, among other things, you need to change your zincs.

A remark:

In the two years I've owned my CATs, I've only had to change out the zincs once each season. Both times I've changed the zincs, all 22 of them, 11 each motor, they've only been at most 60% 'used', many of them only 5% 'used'.

A question:

Will zincs get eaten up simply by being in the motor or do they have to be in the motor AND emersed in water.

An observation:

Most, actually I'm pretty sure all, of my zincs, where they are located in the motor, are above the water line. When the boat sits, other than where it is 'caught' in bends and loops, the sea water naturally drains back down to the water line. In fact, when I change out the zincs, none of the holes have any sea water in them.

So, do I really need to change the zincs simply because the motors are sitting or is it more of a maintenance item.
 
I check the three zincs (top and bottom of the aftercooler, and the bottom of the heat exchanger) in my C series quarterly. They typically show little to no consumption. I change them annually. When I bought the boat, after it sat for a year in salt, the base zonc in the aftercooler was 90% gone and the zinc at the top of the aftercooler was 75% consumed. I think the difference is that we boat exclusively in fresh or brackish water. Guys running C series in salt, like Chad in Asyureyez, see consumption on par with Four Suns.
 
2+ years on our heat exchanger ones in freshwater, little to no breakdown. 3 months in salt water this summer and there was lots of breakdown.
 
osd9 said:
A question:

Will zincs get eaten up simply by being in the motor or do they have to be in the motor AND emersed in water.
Click to expand...

What is the problem that zincs solve?

When dissimilar metals are immersed in an electrolyte, an electric current will flow. The electron flow will carry ions from the anode to the cathode.

How do zincs help? They act as the highest potential anode in the cell. Since they have the highest voltage potential, current flows from the zincs to everything else. Thus, nothing else will erode with the zincs in-circuit.

By now you should see the answer to your question. If there's no electrolyte, then there is no battery cell, and no erosion of the elements that would form the battery if there was electrolyte (water) present.

Best regards,
Frank
 
osd9 said:
I'm resurecting this thread because in 'keeping engine happy' thread. it was mentioned that when the engine sits, among other things, you need to change your zincs.

A remark:

In the two years I've owned my CATs, I've only had to change out the zincs once each season. Both times I've changed the zincs, all 22 of them, 11 each motor
Click to expand...


I assume you are talking pencil zincs. Still seems like a lot. My D6's have only 2 per engine, although they are short, fat guys, sorta like me. I also have 2 plates, one for boat bonding and one for the IPS. The IPS also has a cast iron anode in the exhaust.
 
fc3 said:
What is the problem that zincs solve?

When dissimilar metals are immersed in an electrolyte, an electric current will flow. The electron flow will carry ions from the anode to the cathode.

How do zincs help? They act as the highest potential anode in the cell. Since they have the highest voltage potential, current flows from the zincs to everything else. Thus, nothing else will erode with the zincs in-circuit.

By now you should see the answer to your question. If there's no electrolyte, then there is no battery cell, and no erosion of the elements that would form the battery if there was electrolyte (water) present.

Best regards,
Frank
Click to expand...

"immersed in an electrolyte"

How much immersion needs to take place? Do all metals involved need to be completely submersed in water? I assume when I shut the engines down some water drains, which means there might not be complete immersion of the metals.

Will electric current will flow if there is not complete immersion?
 
SEEG said:
I assume you are talking pencil zincs. Still seems like a lot......
Click to expand...

Yup....11 each motor...3 for the heat exchanger, 2 for the oil cooler 5 for the aftercooler and 1 for the exhaust elbow.



CAT-3126-AnodeKit.jpg
 
fc3 said:
...By now you should see the answer to your question. If there's no electrolyte, then there is no battery cell, and no erosion of the elements that would form the battery if there was electrolyte (water) present.

Best regards,
Frank
Click to expand...

I agree....which is why I am questioning if you really need to change out the zincs in a dormant motor. It's not a bad thing to change them, but I don't see it as a necessary thing to do.
 
osd9 said:
I agree....which is why I am questioning if you really need to change out the zincs in a dormant motor. It's not a bad thing to change them, but I don't see it as a necessary thing to do.
Click to expand...

Same opinion here, but I am no expert on the subject.
 
If the zincs aren't immersed in water, there's no chance of them deteriorating. Period.

Doug
 
osd9 said:
Yup....11 each motor...3 for the heat exchanger, 2 for the oil cooler 5 for the aftercooler and 1 for the exhaust elbow.



CAT-3126-AnodeKit.jpg
Click to expand...

Wow- 5 zincs to protect one component. Wonder why so many?
Guess I've got it easy. Only 3 zincs per engine (heat exchanger) on my 3208's. Engine oil cooler is on the closed side, and there are no zincs on the tranny coolers or elbows.
 
And those 5 aftercooler zincs have a special CAT plug. Not the typical brass plug like in the picture. A CAT $tainle$$ $teel plug. Both times I changed them out, one of the ten zincs threads broke off in the plug and I had to buy new plugs.
 
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