zinc in Universal 5416?

[wumhenry]

Should there be a zinc in my Universal 5416? There's a drain plug in the heat exchanger, but it isn't threaded on the inside.

[FrankLanger]

Yes, the heat exchanger in my universal 5416 has a "pencil zinc" which looks like a nut, but when loosened, has the pencil zinc fitted into it. I change it every 6 months. I understand that not doing this leads to corrosion quite quickly.
Hope that helps.
Frank.

[wumhenry]

Originally Posted by FrankLanger

Yes, the heat exchanger in my universal 5416 has a "pencil zinc" which looks like a nut, but when loosened, has the pencil zinc fitted into it. I change it every 6 months. I understand that not doing this leads to corrosion quite quickly.
Hope that helps.
Frank.

Does the zinc insert into one of the two flat end-surfaces of the cylindrical heat exchanger? That's where the drain plug is on mine.

[FrankLanger]

Unfortunately, I'm not at the boat (it's on the coast, and I'm not ) but as I recall, it's not on either end; rather it's on the cylincrical part of the exchanger--it looks like a nut to undo with a wrench.
Maybe someone else could post a picture....
Frank.

[SailinJay]

I have a Universal M-35B in my boat with a pencil zinc that screws into the heat exchanger. My dealer recommended inspecting the zinc monthly. I think six months is too long because I've gone two or three months and the zinc has worn away significantly, enough to warrant installing a new one.

[Joel73]

We just purchased a Pearson 27 with a Universal M12. Diesel engines are completely new to me so i've got a lot to learn. The surveyor did recommend replacing the zinc pencil which we will be doing within the next week or so... i'll try and snap a picture of it when we replace it. Ours is located on the bottom of the heat exchanger to the left hand side as you are looking at the engine from the back. Wow... every six months huh? Is this an expensive item to replace? I haven't even priced them yet.

[theArchitect]

Hey Wumhenry, I sent a couple messages to your mailbox.

[SailinJay]

Joel73--

Pencil zincs usually run less than five bucks. As I mentioned earlier, you should check a pencil zinc more than once every six months.

[Joel73]

SailinJay- Thanks for the info. Would checking it every 2-3 months be reasonable or should it be done once a month? also, pardon my ignorance but, what exactly does the zinc pencil do? It's just for galvanic corrosion concerns... is that correct?

[BarryL]

Hello,

On the Universal M18 and M25 the zinc is mounted in the heat exchanger. It's on the port side, mounted on the bottom and screwing up into the exchanger.

I check mine yearly and so far I only replace it every other year. My boat is on a mooring so there is very little stray electricity.

Here is a picture

Marine Diesel Direct - Heat Exchanger Group

Barry