Zinc Anode for volvo engine

[Tony Batchelor]

The engine in my CD 30 is raw water cooled as it spent much of its life on the great lakes. Now in NZ I should like to provide some protection against salt water corrosion but the Volvo agent tells me that there is no provision for anodes in the MD series engines.

Never the less I am sure it would be a good idea to fit a zinc. So please can anyone suggest how and where I can fit one, to reduce salt water corrosion

[johnny of STORK]

In mine there's one in the waterlift muffler can. It's easy to get at and change, incredibly enough.

Johnny

[Tony Batchelor]

Thanks Johnny, sorry but I am not at all sure what a muffler can is.
Is the muffler can what we call the exhust mainifold ? In which case I am still puzzled as I did not find any zinc when the manifold was removed last year.

Tony B

[johnny of STORK]

Yes, Tony, I guess I wrote that too quickly. What I called the "muffler can" is the can that the exhaust goes into after it comes out of the exhaust manifold. The pipe that goes into it has the water injection elbow just before it enters the can. Some call it the "water lift muffler". So, it has a steel pipe entering it, and the large rubber/fabric exhaust hose that heads for the transom leaving it. On the side of mine, near the bottom, is a 1/4" pipe thread fitting welded in place, with a brass hex-head zinc-holder threaded into it. When you remove the brass holder, the remains of the zinc will be threaded into the inner end. Or, more likely, a sort of mush will be in the threads. This is pretty easy to clean out, and then you can thread in a new "pencil zinc", which is just a zinc rod, maybe 3/8" in diameter and a couple of inches long, threaded on one end to fit the brass holder. Since the muffler can is in metallic contact with the motor, this system protects the motor from electrolytic damage, at least in theory. If you have one of these, it will be immediately obvious upon opening the motor compartment, as it is right there. If your muffler has been replaced with one of the fiberglass ones, then you will have to think of something else. Hope this helps.

Johnny

[johnny of STORK]

Incidentally, Tony, this is one circumstance where I do *not* use teflon tape in a pipe thread, as that would provide dielectric insulation between the fitting and its threaded sleeve, rendering the zinc ineffective.

Johnny