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Zinc Anode Locations

Perkins 4-108
How many might I have and where would they be located?
Found pencil zincs (1) at a bronze in-line filling just past the raw water pump, and (2) on the heat exchanger.
 

terry_thatcher

Terence Thatcher
lucky you. I just have one in the heat exchanger, unless
I have missed them for 20 years. How is the one after the raw water pump installed? I just have a hose leading out. Thanks.
 

Warren Holybee

Active Member
I zinc protects metal that it is electrically in contact with. The only thing the zinc in the hose fitting protects it the hose fitting itself. Being electrically isolated from the engine, it wouldn't need one anyway. I suspect that fitting was originally installed for something else, not for a zinc.
 
I zinc protects metal that it is electrically in contact with. The only thing the zinc in the hose fitting protects it the hose fitting itself. Being electrically isolated from the engine, it wouldn't need one anyway. I suspect that fitting was originally installed for something else, not for a zinc.
Interesting. Thanks. So why is there a zinc in the heat exchanger? Is it electronically connected? Also, the fact that the zinc do disintegrate, are they not serving a purpose? Appreciate the education.
 

Warren Holybee

Active Member
Interesting. Thanks. So why is there a zinc in the heat exchanger? Is it electronically connected? Also, the fact that the zinc do disintegrate, are they not serving a purpose? Appreciate the education.
The heat exchanger has multiple types of metal, connected to each other, with salt water making it a battery. So without a zinc, there can be corrosion in the heat exchanger, but there shouldn't be much. If the heat exchanger is bolted to the engine, then you absolutely need the zinc as that would electrically connect it.

Consider that your through hulls do not have zincs and do not need them. But if you electrically bond the thru hulls together, then there needs to be a zinc somewhere in the system.

Also, I have an odd engine, a Volvo, which is electrically isolated. The Alternator, Starter, sending units for the gauges, etc, are all special versions that do not electrically connect to the block. I have no negative battery cable connected to the engine. I have no zincs on my engine, or my heat exchanger, and my prop shaft zinc lasts for years without needed service. It is marvelous engineering, the cost being that I need to buy super expensive Volvo parts for repairs.
 

rickdowe2

Richard Dowe
Morning Marc, I have seen a similar unit on another boat and it has a wire from it to the engine which puts it a the same potential as the engine. It intrigued me enough at the time to search for more info on the effectiveness of it but I came up with little information. The black wire that I see in behind it might be the wire that connects it to the engine. Is the zinc deteriorated in it? I thought about making a similar unit with a large zinc, the one on the engines’ heat exchanger does no last that long.
 
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