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Old 08-05-2019, 10:36 AM   #21
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I got an email reply today from Martin Wigg at Performance Metals. Very quick response. He wrote that I can purchase directly from them so Im starting that process.
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Old 08-05-2019, 10:53 AM   #22
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It is worth noting that pipe threads are designed to distort and seal when tightened, one time only. Reused plugs are less likely to seal without some sealer.
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Old 08-05-2019, 11:08 AM   #23
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The Yanmar engine manually specifically indicates that thread tape or sealants should not be used on the zincs. The PO of my vessel used thread tape on them, and after a season, when I replaced them they looked perfect.

I didn't use thread tape when I replaced them. The following year they were more than 50% gone. This tells me that the zincs were doing their job, however the thread tape was clearly preventing them from doing so on the previous installation.
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Old 08-05-2019, 11:14 AM   #24
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NPT threads are not designed to seal without sealant. The thread form has blunt thread tips and roots, and the tolerances for tip and root clearance do not preclude leakage. They are normally tap or die cut and a tapered thread cut that way necessarily has a step the the thread where the tap or die is reversed. Yes, often you can tighten them enough to distort and seal - but they are designed to use sealant. A variant, "NPTF" threads (F is for Fluid) is designed to seal, the specs are tighter and the thread profile is designed to contact at the tip and root. You will not find these in a normal zinc plug or its mating hole though.
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Old 08-09-2019, 03:12 PM   #25
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For those of you who have not discovered Martin Wigg as Performance Metals as a source for Secure-Core AL anodes and who have managed to break off zinc anodes in the brass cap, just toss those caps in a jar with some pool muriatic acid for a half hour or so.
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Old 08-09-2019, 03:42 PM   #26
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For those of you who have not discovered Martin Wigg as Performance Metals as a source for Secure-Core AL anodes and who have managed to break off zinc anodes in the brass cap, just toss those caps in a jar with some pool muriatic acid for a half hour or so.

I finally connected with Martin Wigg and he is sending me some anodes. Hope to have them soon. Nice guy.
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Old 08-10-2019, 01:11 AM   #27
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If you opt to use a paste sealant, apply it only to the wider section of the plug's NPT threads. Doing so will allow the uncoated, narrower section of threads to make good/better low resistance contact with the female threads of the heat exchanger or other part being protected. I'll reiterate, take a few minutes to check resistance to make certain it's under 1 ohm.

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Old 08-10-2019, 04:41 AM   #28
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If it seals without any sealant, why use it?
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Old 08-10-2019, 08:44 AM   #29
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Quote:
Originally Posted by rgano View Post
For those of you who have not discovered Martin Wigg as Performance Metals as a source for Secure-Core AL anodes and who have managed to break off zinc anodes in the brass cap, just toss those caps in a jar with some pool muriatic acid for a half hour or so.
+1 on the muriatic acid trick. Removes all the zinc, leaves a nice, clean cap ready for the next zinc to screw in.
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Old 08-10-2019, 08:44 AM   #30
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about the only sealant that might insulate a pipe plug is teflon tape, depends on how thick the tape and how loose the plug.
NPT means taper, the threads actually grind into each other, a soft sealant will be displaced. And we are talking low voltages and low currents involved with galvanic scale, so as long as ohms between plug and base metal are basically zero its going to work ok regardless of how much thread is covered.
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Old 08-10-2019, 11:05 AM   #31
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I haven't been able to find aluminum pencil anodes - even at BoatZincs.com. Instead I have gone to using magnesium in fresh water and zinc in salt water. Aluminum for the shaft and transom are readily available at BoatZincs.
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Old 08-10-2019, 12:11 PM   #32
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I haven't been able to find aluminum pencil anodes - even at BoatZincs.com. Instead I have gone to using magnesium in fresh water and zinc in salt water. Aluminum for the shaft and transom are readily available at BoatZincs.

That is why the pencil anodes at Performance Metals are good. Aluminum anodes with a SS center to prevent them from breaking off.

I have used zinc anodes for years, but with my new engine, I started to do a fresh water flush after every time I return to my dock. So the anodes are in salt water when away from the dock, but then sit in fresh water between times. As such, I think aluminum makes more sense for my engine. I still use zinc for shaft and hull.
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Old 08-10-2019, 05:04 PM   #33
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If you look at the newer cummins they have plastic end cap on there heat exchanges so no contact with the metal at all to earth out??
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Old 08-10-2019, 05:24 PM   #34
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If you look at the newer cummins they have plastic end cap on there heat exchanges so no contact with the metal at all to earth out??
Perhaps the galvanic currents travel through the ionic liquids, the coolant. If you put an anode in water does it corrode? If it does and its surrounded by a more noble metal must offer protection otherwise Cummins would not bother doing it.
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Old 08-10-2019, 05:30 PM   #35
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I am in low brackish water on the creek, and I have been letting the 2 heat exchange anodes go to pieces and not replacing them. I have Sendure and the tubes and parts are nickel-copper from what I read. When I first got boat, some dummy let the water freeze and cracked a few tubes. I had to silver braze several shut on both exchangers, and that was in 1998. Been working fine. I do in the winter drain them so they sit dry for a few months If it was full salt water I would be more concerned, BUT they are originally made in 1970. AND the cruisair heatexchanger nickel copper tubing is a unit from 1971, and has never had anodes and it is in great condition, so maybe its overrated, IF your heat exchangers are more than just copper and the water is not very salty.
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Old 08-10-2019, 06:21 PM   #36
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Yes i have asked cummins they say so long as it is in the coolant its fine they said a lot of the newer motors are running none metal end caps now
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Old 08-10-2019, 07:14 PM   #37
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Take read here
https://www.sbmar.com/articles/myths...-dope-threads/


shows pics with proof that teflon and pipe dope work fine


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Old 08-11-2019, 03:03 AM   #38
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Perhaps the galvanic currents travel through the ionic liquids, the coolant. If you put an anode in water does it corrode? If it does and its surrounded by a more noble metal must offer protection otherwise Cummins would not bother doing it.
Non-metallic heat exchanger end caps on CAT engines use an embedded bonding strap, which completes the circuit between the anode and the heat exchanger body. If a non-metallic cap has a anode, almost certainly uses this arrangement, if it didn't the anode would be useless.

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Old 08-11-2019, 06:39 AM   #39
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MAYBE a decision was made, plastic caps are cheaper than brass. Let the engine owner bare the burden the cost for the brass plugs.

Yup, maybe it saves only a dime but, a bunch of dimes make up lots of money each year.
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Old 08-11-2019, 11:21 AM   #40
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Plastic wont corrode.
Makes sense the hidden bonding strap. prove it with ohmmeter.

Nickel alloys with copper dont seem to have problems, at least for me with corrosion.

Neither of my engine oil-trans oil coolers have a place for a zinc. Maybe considered expendable. The end of one has developed a raw water weep, it has corroded the outside of the copper. But I dont see it get wet. Solder has failed I think. To take it apart, have to heat entire piece, usually the inner tube are silver brazed, so will survive that.
The ends are soldered on. So someday I will take it apart and fix it.
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