Replacing Engine zincs

ah64a said:
Just a quick question. Do 2000 Mercruisers 5.7 have them too?

Thanks
Click to expand...

I have a 2000~5.7L EFI as well. I have Fresh water (closed) Cooling. I have one zinc on the raw water side of the heat exchanger. I'm trailered and it's only a year old, but I'll check it out and see if it's due for replacement.
 
Storm said:
Jack, don't forget to change zinc number seven (lower port side heat exchanger bonnet). I'm guessing you're counting the two starboard heat exchanger zincs, two in the oil cooler, and two in the fuel cooler. By the way, you should disregard the front zinc in the fuel cooler as it can get sucked into the raw water pump impeller creating yet, another CATastrophe. Storm
Click to expand...
Hey Storm Thanks. I am still trying to figure out where exactly you are telling me that 7th one is. I went to Cat and they only showed the 6. But if there is a 7th I do want to find it and replace it. Any more help is appreciated.
Jack
 
Chris1960 said:
Jack, its the nut that holds the pencil zinc on the cast iron exhaust elbow on my (1996 ) Mechanical 3126's doesnt look like its been replaced for a while
Click to expand...
Chris,
Is the nut you are reffering to brass? No matter what it is before it gets snapped or you round it off I think still a little heat would do wonders to help you. I heat then spray with wd-40 and it tends to loosen things. Let me know if I can help more.
Jack
 
Four Suns said:
I don't put loc-tite on mine and have never had a problem with them vibrating out... and if anyone would have a problem with that, it would be me. I don't think you want to have any kind of substance in the threads that could block electrical current. Not sure if loctite does that or not but it may explain why your zincs last so long. :)
Click to expand...

If you paint them, then they will last a real long time. I saw an ad once for Stainless Steel Zincs that claimed to last much longer than other metals. Is the objective to preserve the zincs or the engine?
 
Last edited:
On 3196 engines, there is nothing between the front fuel cooler zinc and the raw water pump. Best to put the plug in w/out the zinc or risk trashing the impeller blades. Worst case scenario, a new pump costs about $1500. That's worst case if the engine doesn't overheat and crack the cylinder head. Cylinder head goes for about $2500 plus labor.

As for the rest of the zincs, I don't know of any harm that can be done if they break off. If anything, they might serve as more protection. Basically, they are just going to sit there and dissolve.

Storm
 
Broken off zincs will clog heat exchangers and oil coolers as they bounce around inside the cooling system. If we are lucky, they crumble and pass on thru and out with the exhausted sea water, but nearly every heat chchanger I've seen apart, has several tubes blocked by zinc corrosion.

A zinc anode broken off its plug is no longer bonded to the part it is supposed to protect so it no longer protects anything.........its just debris inside the cooling system hunting something to clog up.
 
I don't know if I understand your question or not, but "dissolved zinc particles" from a zinc that is functioning and still in place leaves the zinc as electrons flow and errosion occurs at the zinc. Normal zinc erosion passes on thru with cooling water.

When you get to that point of cleaning a heat exchanger that has disslodged zincs in it, its hard to tell what is zinc and what is just heat exchanger crud because the particles you pick out of the tubes are too small to tell. The zinc junk I see is loose on the inlet end of the tube bundle. Most of the time the zinc has tumbled around and broken up, some passes thru and out but a large portion remains behind to block cooling water flow on the lower tubes. When the pieces stick in a tube, they lay there and corrode.
 
earthmover17 said:
Hey Storm Thanks. I am still trying to figure out where exactly you are telling me that 7th one is. I went to Cat and they only showed the 6. But if there is a 7th I do want to find it and replace it. Any more help is appreciated.
Jack
Click to expand...

Jack, sorry I somehow missed your response. The heat exchanger has three zincs. One on the lower left (port) heat exchanger bonnet and two on the starboard heat exchanger bonnet. The zinc on the left is somewhat hidden behind the oil filter. When removing it, you need to exercise a tad more caution as it wants to leak onto the alternator. You just need to be ready to pop the other zinc in quickly. Better yet, place a rag or oil pad over the alternator while you do the change.

Storm
 
Storm said:
No doubt. I'm afraid we have more problems to worry about with these 3196's than pencil zincs and electrolysis. Vibration, thermal stress, and condensation issues to name a couple.
Click to expand...
Please elaborate. Surely I'm getting way to much sleep at night. I need some more s**t to worry about when I'm 100 miles out to sea in 10 footers.
All kidding aside other than the coolers I did'nt know there were that many problems with the 3196's. Pleeeeeaaaaase enlighten me.
Jack
 
fwebster said:
I made a set of extraction tools for pulling out zincs that unscrew themselves from the plug. I turned a piece of stainless to fit in the pipe threads where the plug goes then drilled and tapped the end of the stainless to fit the threads on the zinc. When I lose one, I stick my handy little thingy in the hole and screw it on the zinc and pull it out.

And you are right..........anytime you see an o-ring on a fitting or plug, it should be tightened enough to just begin to compress the o-ring but not enough to squeeze it out so you tighten the plug against what it mounts in.
Click to expand...

One great idea Frank, thanks that is going in the tool bag ASAP. I'm done fishing those zinc stubs out of the bottom of the aftercooler!
 
OK.....continuing on in this thread I will repeat myself.....'The Zincs in the Aftercooler are possesed by the devil!"....and this time I have a witness.

Yesterday, while doing some near-end-of-season maintenance.....cleaning and re-oiling the airseps filters, cleaning out the bilge, going over everything in the ER and, for the third time since owning this boat, I changed out the engine zincs....11 on each side.

While I was in the 'hole' I heard a knock on the side of the hull, and low and behold, it was Frank...FC3....on his 80MPH jetski stopping by for a visit. Knowing that Frank will someday be a diesel snob himself, I invite him in to the ER for a little Diesel 101.....

With the threat of thunder storms I decided to leave the canvas up.....it was 90F and 90% humid.....and it was Freakin' hot in the ER and getting out these damn aftercooler zincs only made it hotter.

This time, I HAVE one of Frank W's handy dandy extraction tools....so I figure....'Bring it on'....nothing can stop me now.....NOT!!!!

FW's tool...(no jokes please)....is a great idea, but is no match for the aftercooler zincs.....they break off in the hole with the threads in the plug...FC3 can vouch for this and my techniques. I was able to fish out the parts, but that in itself is a test of one's patience....especially in all this heat. I now need to buy three more CAT plugs, at $14.20 apiece....plus a few spares....plus the little O-rings.....10 at $2 apiece....just to finish up the 'devil's aftercooler zinc replacement maintenance'.....

The only thing I hate more than zinc replacement is fixing a computer......which I'm stuck doing right now for my daughter's laptop....
 
Dominci,

My little 'ol tool won't work if you put off changing zincs too long. I had the same problem, i.e. the threads breaking off flush with the zinc body, so I started changing the zincs about every 3 months. Our circumstances are different.......We are in Fla and use the boat 12 months a year + I re-load my zincs so I don't buy the entire plug and annode which reduces the cost significantly. You might try changing your 2X a year and see if you have better results.
 
No aftercooler zincs for me. Everything on the 3208 is on the jacket water system, except of course the heat exchanger which is the only component on the raw water side.

Given the corrosive effect of seawater in general and galvanic corrosion (zincs), why didn't CAT keep all this on the closed side when they came out with the 3116/3126?
 
The 3116 aftercooler is on the closed cooling side......CAT 'upgraded' the 3126 to the raw side.....hence, the 3116 does NOT have zincs in the aftercooler....the 3126 DOES have 5 aftercooler zincs.

I guess the design thought was that cooler raw water used to cool the aftercooler would give better performance. Maybe so, but they sure could have come up with a better way to protect them from the effects of galavanic corrosion....possibly one big ass zinc on some type of removable cover plate on the top of the aftercooler.

In any event, I DID fix my daughter's laptop today!!!!
 
Ah-Hah!!!!! First off....Thanks FC3....why you ask? Well, you saved me the issue of EVER having to buy those overpriced F'n SS plugs from CAT....EVER again!!!!! How you ask?....well, when FC3 was by 'witnessing' the removal of the zincs from hell, we discussed how to remove the zinc parts that were broken off inside the plug.....drill and easy-out is not an option....it doesn't work....I tried and an amateur machinist friend tried and they just don't come out. So, while, FC3 was getting ready to ride off into the sunset on his 80MPH PWC, he made the suggestion, in passing, " why don't you put them in some muratic acid and see how long it takes for the zinc to dissenegrate'....well....it takes about a day and half!!! The plugs came out like new. I salvaged 4 plugs, at ~$15 each. I now have 7 spare plugs.....so next year, when the little bastards break off in the plug, I'll just use the spares, finish the job, soak the broken pieces in an acid bath, and whamo....good as new!!!!

Thanks again......Now....do I need to worry about neutralizing the SS plugs after the acid bath? A littlle baking soda? A quick rinse with water?
 
HAHA! I remember that to get to the 11th zinc I had to lay across the engine with the upper part of my body upside down. Great tip on the acid.

I am happy to only have 2 zincs on each main that I can comfortably reach from the common maintenance point.
 
Sometimes I get lucky.

I still like the idea of redesigning the plugs.
 
You must log in or register to reply here.

Forum statistics

Threads
113,187
Messages
1,428,230
Members
61,099
Latest member
Lorenzo512
Back
Top