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Check your zincs, ALL OF THEM
https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=2036		 Page 1 of 1
Author:  wkearney99 [ Tue Jun 10, 2008 11:40 am ]
Post subject:  Check your zincs, ALL OF THEM
When I was tuning up the genset on our 348 I took the time to also check it's zinc. I was startled to see it nearly eaten through. And this with only 49 hours on it (over the course of three summers though). Instead of the cylinder-like shape it was corroded down like that of an apple core. Well, that's what a zinc is supposed to be doing, so I replaced it. It's an $8 part from west marine, so it's cheap insurance against corrosion eating at the genset itself. Luckily it's the same zinc as the ones used in the 6.0L engines, not something factory-only.

There are also zincs on your engines, propshafts (or outdrives) and main hull. Make sure yours have enough material to continue doing their job. Otherwise corrosion will start eating up much more expensive metals... like cylinder heads, outdrives and the like. And make sure someone hasn't mistakenly PAINTED over any external ones. They need to be clean, bare metal in order to do their job.

And if you check the zincs and they're NOT corroded (and not newly replaced) then you need to find out why. They're supposed to get eaten away. If they're not then something's not right with the electrical wiring to them and you need to get it fixed ASAP.

Speed of corrosion varies widely from one area to another, even from one boat to another in different slips in the same marina. Just get to know how fast yours degrade and schedule their replacements accordingly.
Author:  kinkster [ Wed Jun 11, 2008 5:03 am ]
Post subject:  Re: Check your zincs, ALL OF THEM
Hi Bill, where is the zinc located on the Genset?
Author:  wkearney99 [ Wed Jun 11, 2008 6:31 am ]
Post subject:  Re: Check your zincs, ALL OF THEM
kinkster wrote:
Hi Bill, where is the zinc located on the Genset?

The manual show the location, aka RTFM. Heh.

In fact, look at this PDF on page 17. It's part #20.

Much like the main engines, there's a tube-like heat exchanger tank along the forward end of the engine (on the 5E model genset in a 348, that is). The zinc is a 9/16" head bolt that protrudes from the underside of this heat exchanger. Loosen that bolt and the zinc can be pulled out in a downward direction. This will end up dripping some water and zinc chunks, so have a rag handy to clean it up. Use a 9/16" box-end wrench or socket to loosen it and it'll drop right out. The cylinder might be corroded; that's what it's there for, but it should have enough material to be useful. If it's 80% gone and it's only a year old then you'd obviously want to replace it (and find out what the heck is corroding it so fast). But if it's only 20% gone and it's been 4 years then you've probably got a few more to go. It will vary. But like I mentioned before, at $7 it's a cheap bit of preventative maintenance.
Author:  Graham R [ Wed Jun 11, 2008 9:22 am ]
Post subject:  Re: Check your zincs, ALL OF THEM
For those of you with VP closed cooling, there is an anode on the heat exchanger; screwed into a brass or bronze plug, which is then screwed into the heat exchanger housing. I find they last me one season before they are just over half gone. Often they look almost as if nothing has eroded them, until the anode is tapped onto something hard; then all the zinc chloride corrosion product or whatever just drops off.

Graham
Author:  Blessed [ Wed Jun 11, 2008 10:31 am ]
Post subject:  Re: Check your zincs, ALL OF THEM
Inside the exchanger? Kind of makes you wonder where it all goes after eroding from the anode.

(edit) Oh, nevermind . . . duh. The anode is obviously on the raw water side of the exchanger - what a dumb@$$ thing to say.

Good thing it was mentioned though - It never occurred to me to look for one in there.
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