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06-17-2020, 12:29 PM
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#21
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Guru
City: Brookline, NH
Vessel Name: Shalloway
Vessel Model: Defever 44, twin Perkins
Join Date: Sep 2013
Posts: 2,260
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Quote:
Originally Posted by KnotYet
A zinc will only protect the metals that form part of the circuit it is a part of.
I would want to have separate zincs for any separate metal parts that don't connect.
Also, the further away a zinc is from a metal part the less protection it will provide.
I think those coolers should have zincs of their own unless they are made of special alloy.
I have seen some that do.
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Zincs or any sacrificial anode is only needed to protect dissimilar metals. If a cooler is made from all the same metal or metals that are very close to each other on the galvanic scale then any corrosion is very slow. The higher quality oil coolers are this way so no zinc is needed and they last more than 10 years.
Ken
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06-17-2020, 04:11 PM
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#22
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Senior Member
City: Brisbane
Vessel Name: Malagari
Vessel Model: Island Gypsy 36 Europa
Join Date: Mar 2015
Posts: 422
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Quote:
Originally Posted by kchace
Zincs or any sacrificial anode is only needed to protect dissimilar metals. If a cooler is made from all the same metal or metals that are very close to each other on the galvanic scale then any corrosion is very slow. The higher quality oil coolers are this way so no zinc is needed and they last more than 10 years.
Ken
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Ken,
You make a point re the dissimilar metals and I assume the outer case and inner tubes are the same - no problems - where does the solder holding the end caps on etc fit in the equation - could this be a justification for an anode?
__________________
George
Brisbane
IG 36 Europa
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06-17-2020, 04:36 PM
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#23
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Guru
City: Los Angeles
Join Date: Feb 2020
Posts: 1,487
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Quote:
Originally Posted by kchace
Zincs or any sacrificial anode is only needed to protect dissimilar metals. If a cooler is made from all the same metal or metals that are very close to each other on the galvanic scale then any corrosion is very slow. The higher quality oil coolers are this way so no zinc is needed and they last more than 10 years.
Ken
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Unfortunately, you will seldom find any pure, unalloyed metal in your boat nowadays.
Zincs can also protect against stray current electrolysis as in a zinc on a bronze prop.
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06-17-2020, 04:59 PM
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#24
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Guru
City: Bainbridge Island/Petersburg Alaska
Vessel Name: Oz
Vessel Model: Bluewater 40' RPH 1979
Join Date: Feb 2015
Posts: 514
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One other tip. I always use a plumber's pipe brush to clean the threads and hole in the exchanger when changing zincs. It gets rid of any the crud that builds up and helps prevent the zinc from getting stuck. A useful tool to have in ones arsenal.
Tator
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06-17-2020, 06:52 PM
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#25
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Guru
City: Brookline, NH
Vessel Name: Shalloway
Vessel Model: Defever 44, twin Perkins
Join Date: Sep 2013
Posts: 2,260
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Quote:
Originally Posted by Brisyboy
Ken,
You make a point re the dissimilar metals and I assume the outer case and inner tubes are the same - no problems - where does the solder holding the end caps on etc fit in the equation - could this be a justification for an anode?
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I’m sure it could but don’t overthink it. Some heat exchangers especially the small oil coolers don’t have space for a zinc and
last many years.
Ken
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06-17-2020, 10:50 PM
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#26
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Guru
City: Cape Cod, MA
Vessel Name: Island Seeker
Vessel Model: Willard 36 Sedan
Join Date: Oct 2007
Posts: 1,306
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Am I mistaken or could someone take a piece of oversize zinc rod, turn 2-3" of it down so it just slips through the pipe thread opening, slide a pipe die up that portion and cut the pipe thread, slide it off and grind a hex or cut a slot on the remainder; thus making a one piece zinc?
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06-18-2020, 08:19 AM
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#27
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Guru
City: gulf coast
Join Date: Jun 2014
Posts: 3,440
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Quote:
Originally Posted by catalinajack
I believe that swollen anodes in the heat exchangers is a common problem in Lehmans, probably other engines as well. I got tired of having to remove the end cap and cleaning the bits out. The diameter of the standard anode is 1/2 inch. I switched to 3/8-inch anodes. They, of course, don't last as long but no more having to punch out broken off anodes.
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threaded rod couplers will fit 1/2" zincs
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06-18-2020, 08:47 AM
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#28
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Guru
City: Carefree, Arizona
Vessel Name: sunchaser V
Vessel Model: DeFever 48 (sold)
Join Date: Apr 2008
Posts: 10,185
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Several OEM Cupro nickel heat exchangers are designed and metallurgy speced for no zincs. All Perkins Sabres and Cat 3054/3056 come to mind. I've heard there are others, just not laid eyes on them.
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06-18-2020, 10:20 AM
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#29
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Guru
City: Southport, FL near Panama City
Vessel Name: FROLIC
Vessel Model: Mainship 30 Pilot II since 2015. GB-42 1986-2015. Former Unlimited Tonnage Master
Join Date: Oct 2007
Posts: 4,984
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Quote:
Originally Posted by Brooksie
Am I mistaken or could someone take a piece of oversize zinc rod, turn 2-3" of it down so it just slips through the pipe thread opening, slide a pipe die up that portion and cut the pipe thread, slide it off and grind a hex or cut a slot on the remainder; thus making a one piece zinc?
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You might well end up with a crumbled zinc which would not be removable.
__________________
Rich Gano
FROLIC (2005 MainShip 30 Pilot II)
Panama City area
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06-22-2020, 01:13 PM
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#30
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Veteran Member
City: Safety Harbor
Vessel Name: Yankee Peddler
Vessel Model: Grand Banks Eastbay
Join Date: Jul 2014
Posts: 42
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Dialelctric grease is an insulator. It is printed on the tube. If you use it test with an Ohm meter.
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06-22-2020, 02:51 PM
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#31
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Veteran Member
City: Seattle
Vessel Name: NANCY J
Vessel Model: GB 42 Classic
Join Date: Jul 2010
Posts: 51
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I filed the outside threads off the brass nut and then threaded it back on the threads on top of zinc. Turn until tight on zinc and then another turn which will free the zinc in the hole and then remove both zinc and nut. Get a new nut and zinc and you are good to go.
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06-22-2020, 03:30 PM
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#32
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Member
City: St. Pete, FL
Vessel Name: Freebird
Vessel Model: Kadey Krogen North Sea
Join Date: Feb 2012
Posts: 10
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No. Teflon tape will prevent continuity thus defeating the purpose of the zinc.
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06-22-2020, 03:39 PM
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#33
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Senior Member
City: Essington, PA.
Vessel Name: Nepidae
Vessel Model: Albin 43 Sundeck
Join Date: Jul 2013
Posts: 370
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Ford Lehman Heat Exchanger
Please read:
THERE IS NO ONE WHO KNOWS THE FORD LEHMAN ENGINE LIKE BRIAN SMITH.
Look here for contact info: https://americandieselcorp.com/
His dad marinized the engine, plus aside from his knowledge on any version of engines, he also has parts.
ANYONE on a forum is passing on their experience, not necessarily what is FACT.
Call Brian.
__________________
Best regards,
Charles
Charles Williamson
m/v Nepidae, Albin 43 Sundeck
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06-22-2020, 04:58 PM
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#34
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Guru
City: Los Angeles
Join Date: Feb 2020
Posts: 1,487
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Quote:
Originally Posted by DLaNeve
No. Teflon tape will prevent continuity thus defeating the purpose of the zinc.
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Most of the time using teflon tape on a zinc plug won't affect its function. The tape
is so thin and weak that metal to metal contact will occur. I suppose if you used a lot
of wraps of really thick tape and didn't tighten it much there could be a problem though.
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06-22-2020, 05:19 PM
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#35
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Moderator Emeritus
City: Au Gres, MI
Vessel Name: Black Dog
Vessel Model: Formula 41PC
Join Date: Jul 2015
Posts: 21,185
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I don’t use anything on my heat exchanger anodes. Never had them leak yet...
__________________
Boat Nut:
If you are one there is no explanation necessary.
If you aren’t one, there is no explanation possible.
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06-22-2020, 07:03 PM
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#36
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Guru
City: Brookline, NH
Vessel Name: Shalloway
Vessel Model: Defever 44, twin Perkins
Join Date: Sep 2013
Posts: 2,260
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Quote:
Originally Posted by Comodave
I don’t use anything on my heat exchanger anodes. Never had them leak yet...
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Ditto
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06-22-2020, 10:16 PM
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#37
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Guru
City: Deltaville
Join Date: Dec 2015
Posts: 1,069
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Quote:
Originally Posted by Insequent
I get the crusty stuff on my anodes as well. In my case I think it comes from river water at my marina being less salty than the ocean. I've decided to replace them more often, as I've had some break off as well even though only 'half worn'.
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Indeed, zinc is not ideal for use in fresh water, when exposed to it it develops a coating, which causes the zinc to go dormant; it will not work when returned seawater. The coating can be cleaned off with a non-metallic brush of scotchbrite pad.
Zinc is not suited for fresh water, aluminum anodes work in salt, fresh and brackish, and I recommend them with the exception of heat exchanger pencil anodes, the aluminum anodes tend to swell slightly, making them difficult to remove from the heat exchanger. The erosion level in FW is pretty low, so OK to stay with zinc and just clean or replace when reentering seawater.
As noted by others, the anode is not effective once it electrically separates from the heat exchanger/plug.
Heat exchanger end caps should be removed and the internals cleaned every two years or so, zinc pencils tend to accumulate there, along with other debris. I've encountered heat exchangers where half the tubes were blocked by old anodes.
More on heat exchanger maintenance here https://stevedmarineconsulting.com/w...March-2012.pdf
(In Taiwan)
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06-22-2020, 10:29 PM
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#38
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Moderator Emeritus
City: Au Gres, MI
Vessel Name: Black Dog
Vessel Model: Formula 41PC
Join Date: Jul 2015
Posts: 21,185
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I use magnesium anodes in my heat exchangers since I have not found aluminum ones in the size I need. They also seem to swell up and it ends up with me having to take the heat exchanger end cap off to get them out.
__________________
Boat Nut:
If you are one there is no explanation necessary.
If you aren’t one, there is no explanation possible.
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06-23-2020, 01:47 PM
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#39
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Veteran Member
City: Safety Harbor
Vessel Name: Yankee Peddler
Vessel Model: Grand Banks Eastbay
Join Date: Jul 2014
Posts: 42
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The useful life of anodes depends upon the electrical current present and the volume and pressure of the cooling water. Cat engines as an example run a lot of water thru the cooling system and use up zinks quickly and should be monitored often. The zink may look fine, but tap it with a light hammer and it may disintegrate leaving part of it in the cap which can be removed by imersing it in a container of murieatic acid for a limited time. If pieces are left inside the heat exchanger you may be able to suck them out with a shop vac.
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06-23-2020, 09:48 PM
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#40
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Senior Member
City: Beaufort, SC
Vessel Name: TAMI II
Vessel Model: Tollycraft, 44 CPMY
Join Date: Aug 2016
Posts: 148
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Quote:
Originally Posted by Mike Negley
The useful life of anodes depends upon the electrical current present and the volume and pressure of the cooling water. Cat engines as an example run a lot of water thru the cooling system and use up zinks quickly and should be monitored often. The zink may look fine, but tap it with a light hammer and it may disintegrate leaving part of it in the cap which can be removed by imersing it in a container of murieatic acid for a limited time. If pieces are left inside the heat exchanger you may be able to suck them out with a shop vac.
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Mike, Thanks for verifying this for me. I find that if I don't change my Cat 3208 zincs every 4 months I'm taking something apart to look for a broken zinc. Even if they appear intact they get replaced at this point because as you point out, they are very fragile after this amount of time.
I can go 6 months or maybe a little longer but the headaches of a broken or stuck zinc get worse.
I've often wondered if simple water flow/pressure could could be a significant variable. Other than abrasion I'm not clear on the mechanism for this if it's not related to dissimilar metals. Seems that abrasion would affect only the outer shell of the zinc but these older but "intact" zincs seem rotten to the core. I'm guessing it's a combination of variables.
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