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2001 350 5.7 MAG MPI - Heat Exchanger - retrofit a zinc in there ?

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abl1111

Regular Contributor
I have a 2001 350 5.7 MAG MPI ( Freshwater cooled ) motor that I just replaced the heat exchanger ( got a new one under warranty ! ) due to one of the hose nipples was obviously crushed during initial install in 2001 and finally the thing rusted out...

Motor has 500 hours and I am still running original elbows, risers and manifolds !!! All running well - cool as a cucumber ! They look great and so did the heat exchanger other than this nipple issue.

THE QUESTION:

My exchanger has the blue, plastic, drain-knob that gets threaded into the exchanger. I was thinking if it would be a good idea to remove that and install a threaded 'zinc' in there for electrolysis protection...

Thanks
 
Depends. If the drain cock is on the antifreeze side you don't need a zinc. Otherwise yes it won't hurt, but probably not as necessary as you would think, especially if the boat is on a trailer.
 
Hmm, I think the blue plug is in the antifreeze part. I doubt that a zinc could be retrofitted on the raw water side - I don't even know if and where there is a drain for the raw water on the exchanger...
 
You need a zinc if the boat is kept in the water, especially at a marina where the possibility of stray current being present is high. The water, especially salt water, accelerates electrolytic corrosion. This is the oxidation you see when two different metals touch each other. The zinc, being less "noble" than other metals will lose material first before the other, more important parts (like your drive housing)
All things considered, the drive should have enough anodes to handle at least a season's worth of submersion without adding more.
 
o2batsea said:
You need a zinc if the boat is kept in the water, especially at a marina where the possibility of stray current being present is high. The water, especially salt water, accelerates electrolytic corrosion. This is the oxidation you see when two different metals touch each other. The zinc, being less "noble" than other metals will lose material first before the other, more important parts (like your drive housing)
All things considered, the drive should have enough anodes to handle at least a season's worth of submersion without adding more.
Click to expand...


with marina docking the electrical currents are flowing thru the boats/water at a good rate. I know of a marina in my area very close to high voltage power lines. the zincs on the big boats need divers to replace at mid season.
 
Agreed.... these are called "Pencil Anodes"
Any Copper/Bronze Heat Exchanger should have a "Pencil Anode" threaded into the sea water side drain port.
Zinc seems to be the material of choice!

When you purchase these, buy yourself at least a half dozen or so. We may end up changing these two/three times annually!
And never assume that the anode portion alone threads into all brass plug units.... they do not! :mad: Some even in the same batch will have different threads! (dang Chinese crap!) :mad:

The E/G side very likely will NOT have a drain port! If it does, it's not one that I would be familiar with.
(if this is the upper/horizontal H/E installation, you pull the Circ Pump hose connection loose, and there's your coolant drain!)

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