Inner Cooler zincs Broke Off

[Reveille75]

I was changing the zincs in my C7's inner cooler. You know the ones that are way down low on the starboard side of the engine. The one that is trying my civility is on the starboard engine and it is virtually impossible to get to. The zinc has broken off the plug and I can't get to it very well. I can take the inner cooler off and remove the zincs properly or I can push them on in the inner cooler and let them be zincs and go away. Whats wrong with taking the easy way out on this one? As lazy as I am, I'll do what has to be done if my natural tendencies will impact engine life.
Tell me what you think.

[badhabit]

I'm thinking the zink would have to be threaded in and be grounded to "go away" ,I know you are not suppose to use thread tape or pipe dope on zinks to make sure they are grounded, but by no means am I an expert ,just my 2 cents,

[Reveille75]

Badhabit:
It seems that if the zinc was laying against an interior surface it would be "grounded'. Perhaps not as solidly as if it were on the threads but still ought to go away. Anyone else have a thought.
david

[Storm]

My pencil zincs break-off frequently and I don't waste my time trying to fish them out. Some people think zinc floating around in the expansion tank inlet or a cooler is an issue. I don't agree. My theory is that sea water is an electrolytically conductive medium, and therefore loose zinc pieces submersed in sea water and in the immediate proximity of metal will be grounded and corrode. Sometimes minute zinc particles will find their way into the heat exchanger tube bundles and attach themselves to the tubes. I don't see this as being a big problem unless you have a whole lot of broken zinc pieces in the upstream side of the heat exchanger. And, I suspect this explains why Cat decided to locate the upstream zincs on the lower half of the heat exchanger, versus the top and lower half of the downstream side of the heat exchanger. As for cooler zinc particles, they should flush harmlessly out through the raw water cooling system.


On Cat 3196 and C12 fuel coolers, there is a zinc upstream of the raw water pump that I replaced with a plug because there's nothing between the zinc and the raw water pump impeller. In this case, a broken zinc could be sucked into the impeller and cause considerable damage. Replacement raw water pumps are about $1500 and the cost to repair an overheated engine is significantly more.

I don't know whether or not C7's are equipped with fuel coolers and if they are, whether or not the coolers are directly upstream of the raw water pump.

[seapower]

I remove broken off zinc's. I can't begin to tell you the number of zinc's I've retrieved out of overheating engine's, that were supposed to melt away. You've got to have a pretty good ground for the zinc to be sacrificial, it's moving around with the force of the water flow. You should not use tape, pipe dope etc... to the plug thread's. This can insulate the zinc and not allow it to do it's job. I might add something a little extra here, when replacing your zinc's, unscrew the zinc from the plug, put a little "red lock-tite" to the threads (the threads on the zinc, not the plug to the cooler), put the zinc back into the plug and snug it down. This will help keep your zinc's from coming loose from the plug's. Try it, it work's. Just my opinion, but what do I know. Frank

[Reveille75]

Sea power I expect you know a great deal. I was told that a zinc could bounce around in the cooler chamber and damage the fins on the internals so I am going to remove the shot zincs. I had to take the transmission cooler off to get it done. You can bet I'll try a little lock tite. Thanks for a great tip.
David

[kidIsurus]

I remove broken off zinc's. I can't begin to tell you the number of zinc's I've retrieved out of overheating engine's, that were supposed to melt away. You've got to have a pretty good ground for the zinc to be sacrificial, it's moving around with the force of the water flow. You should not use tape, pipe dope etc... to the plug thread's. This can insulate the zinc and not allow it to do it's job. I might add something a little extra here, when replacing your zinc's, unscrew the zinc from the plug, put a little "red lock-tite" to the threads (the threads on the zinc, not the plug to the cooler), put the zinc back into the plug and snug it down. This will help keep your zinc's from coming loose from the plug's. Try it, it work's. Just my opinion, but what do I know. Frank

I understand where you are going with this, however, in most cases if a zinc breaks off, the threaded part of the zinc stays in the "plug" so the loctite would not help. I know this won't happen but engine manufacturers should increase the id above the pipe thread to prevent the zincs from breaking when you attempt to remove them. The reason the zincs break is due to salt build up above the pipe thread and when you try to remove them they seperate from the threads. We know the manufacturers aren't going to change so the next best thing is to check/clean/change your zincs more frequently. Make zinc inspection one of your regular service items (every month) I assure you this will prevent the salt buildup causing your pencil zincs to break.

[seapower]

like I said "what do I know"? I use the "lock-tite" and for the vast majority of the time the zinc hold's to the plug. Oh by the way Caterpillar started doing the same thing a few year's back. Maybe they should have had a consult first. Again I'm not the brightest light in the harbor, it was just a tip, take it or leave it. I only report what I know work's. Frank