Why doesn't my Perkins have any Zincs?

MedSailor · #1 04-01-2013

One thing I can't seem to figure out about my Perkins 4.108 is why it doesn't have a zinc. My Yanmar did. The perkins has multiple different metals in contact with seawater, and yet no zinc is designed into the system.....

Pray tell why? I'd like to believe that since I have "one of the most reliable engines in the world" that it's all okay and the British engine designers are really geniuses above all other engine makers. But then again, these are the guys that are STILL using cork gaskets and making an engine that leaks on the show-room floor.

I ask because I just noticed a dripping leak from my raw water pump yesterday. It's pretty green and rusty right now, and my raw water strainer is looking a little green too....

Should I add pencil zinc myself on the raw water side somewhere? I've got lots of exotic custom plumbing (that's all turning green) to feed the engine and the hot water heater. I could add a zinc in there easy enough.

Good idea? Bad idea???

MedSailor

swampcreek · #2 04-02-2013

You probably have the same situation as me and my Yanmar...

I went through this last fall. I bought 2 pencil zincs because the manual stated that the 3GM30 had zincs that required maintenance. I bought 2 and went to the boat. I could not find the screw plugs that the manual said was there! I went back to the shop and they asked if I had a 3GM30 OR a 3GM30F? I said I had the 3GM30F. I was told that the fresh water cooled (IMO should be known as antifreeze cooled) Yanmars didn't need zincs due to the special metal used in the exchanger...So I researched because I'm nuts about boat things and I need to know! I found out that the material used for that heat exchanger was something called cupronickel which has a very high resistance to corrosion, many heat exchangers are simply copper and do require zinc protection. Here is a link on Cupronickle.

Cupronickel - Wikipedia, the free encyclopedia
Cupronickel - Wikipedia, the free encyclopedia

SimonV · #3 04-02-2013

The zinks on the Perkins 4.108 are in the heat exchanger only.

aeventyr60 · #4 04-02-2013

My 4108 has no zinc in the heat exchanger. It has been explained to me that the rubber end caps on the tube stack isolates the brass/bronze tubestack from the surrounding metal. Correct me if I'm wrong?

MedSailor · #5 04-02-2013

Quote:

Originally Posted by aeventyr60

My 4108 has no zinc in the heat exchanger. It has been explained to me that the rubber end caps on the tube stack isolates the brass/bronze tubestack from the surrounding metal. Correct me if I'm wrong?

This makes sense! Thanks for that revelation!

It also makes sense as to why all my custom copper tubing and my bronze raw water pump and strainer are turning to green powder... Hmmm.... Methinks I should zinc the bits before the rubber caps.

Perhaps a stupid idea, but what about just dropping a zinc into the sea water strainer basket? Something like a half-eaten shaft collar zinc? Wouldn't satisfy the anal engineer in me, but it would satisfy the "get-er-done" part of my brain.

MedSailor

Faster · #6 04-02-2013

We have no zincs either, Bowman H/E with isolated bundle and stepped rubber caps. Haven't had any issues.

casey1999 · #7 04-02-2013

Quote:

Originally Posted by MedSailor

This makes sense! Thanks for that revelation!

It also makes sense as to why all my custom copper tubing and my bronze raw water pump and strainer are turning to green powder... Hmmm.... Methinks I should zinc the bits before the rubber caps.

Perhaps a stupid idea, but what about just dropping a zinc into the sea water strainer basket? Something like a half-eaten shaft collar zinc? Wouldn't satisfy the anal engineer in me, but it would satisfy the "get-er-done" part of my brain.

MedSailor

The zinc needs to be in physical (meaning also electrical contact for metal equipment) to work. The zinc is setting up a battery with the salt water being the electrolyte. Dropping zinc in strainer would do nothing as it is not in good electical contact with what you want to protect and it needs to be in close proximity (within a few inches) of what you want to protect. This is why some say the zinc fish you connect to your boat and drop over the side do nothing to protect your boat metals.