Heat exchanger advice please

[Tim]

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.

 

[DLaNeve]

No. Teflon tape will prevent continuity thus defeating the purpose of the zinc.

 

[Nepidae]

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.

 

[KnotYet]

No. Teflon tape will prevent continuity thus defeating the purpose of the zinc.

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.

 

[Comodave]

I don’t use anything on my heat exchanger anodes. Never had them leak yet...

 

[kchace]

I don’t use anything on my heat exchanger anodes. Never had them leak yet...

Ditto

 

[Steve DAntonio]

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'.

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/...EAD-Heat-Exchanger-Maintenance-March-2012.pdf

(In Taiwan)

 

[Comodave]

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.

 

[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.

 

[ORIF]

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.

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.

 

[Steve DAntonio]

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.

You should use Mg anodes only if you operate exclusively in fresh water.

(In Taiwan)

 

[Bacchus]

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.

Dave
I'm in fresh water and use all alum anodes as I couldn't find everything needed in Mg.
I have switched to Performance Metals pencil anodes for several reasons. They have a great selection of both bare anodes and complete units. Their pencil anodes have a steel rod/wire in the center that helps prevent breakage and need to fish out broken pieces.
I have build a "kit" box of all my anodes w both rods and complete units. I'll clean up old caps with muriatic acid and replenish the kit as needed to keep both on hand. A listing of which ones fit each Ht XChgr taped inside the cover avoids any questions.

anyone use anti seize, dielectric grease or even just a grease.

I have never used or needed teflon tape to seal but do use a LITTLE dab of anti-seize on pencil anodes to make removal EZ. So far no issue getting conductivity.

A couple other tricks I have found useful...

The threads of the cap and rod are about the same L and did not allow threading into the rod w/o catching the cap threads. I have taken an old hex cap and ground the threads down so it will screw onto an anode left in place but not into the Ht XChgr. That let's me continue to "tighten" and rotate the anode and pull it out with pliers or vise grips.

Where the Ht XChgr opening is very close to the pencil anode beyond the threaded cap I have painted a ring around the alum rod for a short ways. The rest of the rod is clean and works to protect but that ring is less affected and seems to come out without issue. Checking, cleaning and reinstalling more often will do the same.

 

[ORIF]

Dave
I'm in fresh water and use all alum anodes as I couldn't find everything needed in Mg.
I have switched to Performance Metals pencil anodes for several reasons. They have a great selection of both bare anodes and complete units. Their pencil anodes have a steel rod/wire in the center that helps prevent breakage and need to fish out broken pieces.
I have build a "kit" box of all my anodes w both rods and complete units. I'll clean up old caps with muriatic acid and replenish the kit as needed to keep both on hand. A listing of which ones fit each Ht XChgr taped inside the cover avoids any questions.I have never used or needed teflon tape to seal but do use a LITTLE dab of anti-seize on pencil anodes to make removal EZ. So far no issue getting conductivity.

A couple other tricks I have found useful...

The threads of the cap and rod are about the same L and did not allow threading into the rod w/o catching the cap threads. I have taken an old hex cap and ground the threads down so it will screw onto an anode left in place but not into the Ht XChgr. That let's me continue to "tighten" and rotate the anode and pull it out with pliers or vise grips.

Where the Ht XChgr opening is very close to the pencil anode beyond the threaded cap I have painted a ring around the alum rod for a short ways. The rest of the rod is clean and works to protect but that ring is less affected and seems to come out without issue. Checking, cleaning and reinstalling more often will do the same.

Bacchus, I’m curious what you use to paint the zinc rod base in the instances where it touches the part you’re screwing into?

That’s got me thinking this is the main issue I have if something breaks off and may be a good solution. Zinc should sill be in continuity with the protected part via its threaded post in the plug and the rest of the zinc is exposed. I’m assuming you just paint a stripe at the base?

However, in the short stubby exhaust elbow zincs, it seems that there is a ring of zinc that gets eroded away right at the base where it joins the plug. Possibly due to high water flow in that area?

Does anyone smarter than me see a problem with this practice (Steve D’Antonio)

 

[Bacchus]

ORIF
Yes just a ring around the rod at the base.
I have used nail polish as my wife had some on hand. It seemed to help but I'll admit it wasn't an extensive test. I think the Performance Metals anodes helped the most.
High flow or turbulence may affect where the erosion occurs. Mine tend to erode towards the free end and build up oxide? Sludge? Near the base. On mine the clearance at the base is tight and caused some binding and the rod unscrewing from the cap.

 

[RickyD]

My lehman transmission and oil coolers have drains, no anodes. Unfortunately the first warning you get of corrosion is a transmission full of water. Not aware of any solution.

I replaced and relocated my Cat 3208 gear coolers to Volvo with large zinc protection and port side with easy access.

 

[rgano]

My lehman transmission and oil coolers have drains, no anodes. Unfortunately the first warning you get of corrosion is a transmission full of water. Not aware of any solution.

Sure you are. Replace what you have with Cupro-Nickle units and replace them every five years. You will have no horror stories.

 

[Steve DAntonio]

Where the Ht XChgr opening is very close to the pencil anode beyond the threaded cap I have painted a ring around the alum rod for a short ways. The rest of the rod is clean and works to protect but that ring is less affected and seems to come out without issue. Checking, cleaning and reinstalling more often will do the same.

That's a great idea!

(In Taiwan)

 

[Dougcole]

I'm having an issue getting the stuck anode out of the HE on my generator. The threaded tip broke off in the hex cap and there is not enough of it left inside the HE to grab it from below. Not enough swing room on top to get to it to tap the piece out of the hole. Tried using a 90 degree screwdriver but it didn't work. I'm starting to think I may have to pull the HE and do it on the bench.


Maybe a few drips of muratic acid?

 

[Mike Negley]

Try a shop vac.

 

[rgano]

I'm having an issue getting the stuck anode out of the HE on my generator. The threaded tip broke off in the hex cap and there is not enough of it left inside the HE to grab it from below. Not enough swing room on top to get to it to tap the piece out of the hole. Tried using a 90 degree screwdriver but it didn't work. I'm starting to think I may have to pull the HE and do it on the bench.


Maybe a few drips of muratic acid?

I use a few ounces of muriatic in a glass jar to boil out anodes, zinc and/or aluminum and let it sit for an hour or two. I have anode holders decades old I have treated this way.

If you have an eye dropper and the zinc is sitting vertical in its port, it would not hurt anything to put a few drops in until it lets go and falls away. Just flush the area when you are down with plenty of water.

 

[Comodave]

You should use Mg anodes only if you operate exclusively in fresh water.

(In Taiwan)

Yes we are on the Great Lakes. I would use aluminum in the heat exchanger but I could not find the correct size so I went with magnesium. For the hull, shaft and trim tabs I use aluminum since it is effectively a different body of water.

 

[kthoennes]

This is an old thread I know, but I just wanted to say thank you for this discussion and others about engine and heat exchanger zincs (anodes). Wouldn't have occurred to me otherwise. It's been on my to-do list since last year but didn't get to it, and I figured fresh water, I'll do it later. Finally got to it this weekend. Yikes!! New ones on order. Won't neglect that again.

 

[Comodave]

You did order aluminum or magnesium anodes, right? I ask because you said zincs…

 

[kthoennes]

Yes, magnesium. I try to break the habit of calling all anodes "zincs" but that habit runs deep.

 

[Comodave]

I try to get people to say anodes rather than zincs but it is difficult to break old habits.

 

[kthoennes]

Yeah, just a little different.

 

[C lectric]

When I replace my pencil anodes for the heat exchangers I use a wee bit of REctorSeal #5 on the anode threads. Gobs are not needed. This keeps the seawater out of the threads so they stay intact. THere are other sealers that can be used.

If at home I put the anode into the vise and firmly snug the cap onto the threads.
If on the boat I use an appropriate box end wrench for the cap and a pair of Vise grips to hold the anode while I turn the wrench.
After starting that I have had NO problems with losing the anode in the exchanger.

I also use my DMM to check that there is metal to metal contact between the plug and the anode.

I also put some of the sealer on the cap thread as I install the assembly into the exchanger. Again gobs are not needed but since starting that there are no leaks.

THen after installing the anode into the exchanger I use the DMM again to check that there is metal to metal contact between the cap and the exchanger.s
This ensures a good connection between the anode itself and the exchanger body for protection.

If the meter does not show literally 0.00 ohms or 0.01 ohm at each test point I will redo the connection fitting.


Do not assume that you can decide beforehand to change those anodes on YOUR schedule. It will take some effort but you should check each anode monthly, a suggestion, at least untill you determine which anode needs to be changed when. THey will all have their own schedule of depletion and failure to do these checks to determine THEIR schedule will cost you.
Some will be gone in one or two months, others may last 6 or 8 months. You must determine that interval.

 

[ssurabus]

There are new engine anodes on the market that directly addresses the problem of stuck/broken zincs as expressed by the original poster. It uses a plug that acts as a puller to relieve all torque on the rod and only apply force along the length - its strongest direction. This prevents breakage at the fragile shoulder area where the rod transitions from its full diameter to the thinner portion that resides in the plug cavity. Also, it does not use internal threads to hold the rod in place, so it can't unthread leaving the rod behind. They are called REDZn Engine Anodes. They've been a welcome change on my Mainship (15 zincs between the Yanmars and the Kohler). I'm happy to answer any questions but will not pontificate on the forum unless people want more information, as I am the designer and do not want to overstep.

--Howie