Corrosion of Alde Convectors

Dalehelman · May 2021

@BrianZ
Wow that looks really bad. Do you know of others that are that bad? Most of what I have seen appears to be only surface damage.

BrianZ · May 2021

ChanW said:

That Loctite sealant Alde sells says in its docs, 'to remove, soak in alcohol.....' Seems that would make it pretty useless against glycol!

I wonder if anodizing the ends would have been a preventative. Or maybe high-temp silicone grease?

I also agree, those clip type clamps don't seem to be as dependable as a screw type. But the screw type doesn't seem to fit the circumference as well as the clip type does. I wonder if the screw type would press the rubber against the aluminum as well, all the way around, as the clip does.

Here's what I ordered (Amazon I think)..
(Way more than I would need, so willing to pass it on after I'm done, if anyone needs some.)

And the usage/instructions..

Image: https://us.v-cdn.net/5021717/uploads/editor/gg/cbjidgiqss0y.jpg

It says that it resists water, antifreeze & a bunch of other stuff. Ingredients list talc, quartz, and 2-propanol, which is another name for isopropyl ("rubbing") alcohol.

I can't help but wonder if this contributes to the corrosion, but surely not if it's used in airplane engines? In any case, Alde surely recommends it for this purpose in their catalog..

Image: https://us.v-cdn.net/5021717/uploads/editor/u6/2iff4zmsbq7g.jpg

BrianZ · May 2021

Dalehelman said:

@BrianZ
Wow that looks really bad. Do you know of others that are that bad? Most of what I have seen appears to be only surface damage.

@Dalehelman, I think @ScottG had said only 3 or 4 had taken hoses off to look, but as I recall @fstop32 was the worst, & the others were more like just the surface, although one attempted repair for a small hole using JB Weld failed due to heat on the plastic, if I remember correctly.

tybladesmith · May 2021

@BrianZ, I sent an email to Chantel at Alde/Truma asking why the Loctite 5923 was recommended in the 3010 installation manual but not in the 3020 installation manual. I doubt that NuCamp ever used the product. I also inquired about the ground bonds that are referenced in the Airstream recall notice. Crickets.....from Alde.

BrianZ · May 2021

Great question, @tybladesmith! I wonder if they will respond, but I think the answer is that the Loctite 5923 may be promoting corrosion in the longer term, even if it might reduce leaks initially. I say this, because I believe the white looking deposits I'm seeing on my connectors are the sealant, which I've been able to scrape off for the most part (carefully, using my fingernail and a short piece of pvc pipe as a hand tool scraper), and underneath I see in some places that appears to be pitting on the surface when magnified, even though mine are in relatively good shape - no significant loss of metal.

I would guess that NüCamp was using the sealant on ours. I think soaking the ends in rubbing alcohol (by wrapping soaked cotton makeup pad & wrapping on the pipe end with cling wrap) may have softened them up a bit for removal. I'm not sure how to proceed from here - more Loctite to cover whatever damage might have been done, or heat shrink tubing to protect it? Will post some photos here soon.

Dalehelman · May 2021

Those of you who have drained their system. Do you have any idea how much coolant it held?

400
320 with bath
320 CS with bath
It seems considerable less than I expected. Our 320S was right at 6qts. Another members 320 CS was 7qts.

BrianZ · May 2021

@Dalehelman, ours was around 2G, maybe 7Q, but I'll know better when I refill it, because I'm sure it's empty now, having opened drained, flushed multiple times, blown out with air, and now having opened the drain as well as the lowest part of the convector loop.

BrianZ · May 2021

Here are photos of our rear driver-side convector connectors..
Only the top one (first one from Alde) has been cleaned up. Lower one has some raised white deposits on it.

Image: https://us.v-cdn.net/5021717/uploads/editor/uq/7darfj1pt81p.jpg

And both cleaned..

Next is the side convector at front end of the loop..
Both have been mostly cleaned, except top one has a lump near the lower part which shows how it is raised.

Image: https://us.v-cdn.net/5021717/uploads/editor/gp/i3rii789r8nx.jpg

Below is a close-up view of the area of the lump after it was cleaned off. This appears to me to show pitting in the surface of the metal, as in the process of corrosion.

Image: https://us.v-cdn.net/5021717/uploads/editor/ze/ki9tz0higtrc.jpg

And below are the same side convectors, showing the unremarkable inside. It appears to me there is nothing abnormal inside, and it feels smooth to touch, unlike the outer surface which felt rought before cleaning, but fairly smooth afterwards.

Still mulling over what to do next, but I don't want to wait too long. What would you do?

Tabaz · May 2021

BrianZ - a little off topic here, but what camera are you using? Your pictures are amazingly detailed and clear.

BridgerSunset · May 2021

@BrianZ,

Outstanding job describing what you've found. Your & the others' work will get to the root cause at some point. Inside the pipe looks fine, and that's very very good news.

You posed the question "what would you do?"

I'd focus on that electrical conductivity between the outside of the convector pipe and whatever is touching it (either liquid, solid, or gas). My experience included cathodic protection, internal plastic coating of tubular steel, external epoxy coating of line pipe & internal coating of tank walls. Since failures meant immense costs, we went to great lengths to eliminate "holidays" (points where current can sneak through) in the coating. Corrosion is a flow of electrons, and a 100% "holiday free" coating stops the flow, even if the root cause isn't completely understood.

So anything you can do to that end - like coating with a dielectric coating, wrapping with electrical tape, heat shrink sleeves, paint, or the other ideas brought up in this thread - should buy you time, provided it is rated for the temperature of the system. Cleaning the pits out thoroughly like you did is important.

If the pits aren't too deep and the coating you place does its job, the risk of blowing new holes in the convector pipe should be pretty low with the low system pump pressure.

ScottG · May 2021

@BrianZ, I'm sorry to hear your report. I'm also a little surprised--given the age of your T@B I would not have expected that degree of deposits/corrosion. I supposed the good news is that your components looked very similar to mine, so maybe (wishful thinking...) the progression is slow in most cases.

You are correct regarding the history. I think you are the forth to report dismantling the connections. All who have done so have reported some degree of corrosion, with only @fstop32 finding complete degradation in some areas. A similar number of other owners have reported telltale bulges, but to the best of my knowledge have not inspected things more closely.

How much use has your system had? Anecdotally, it seems the worst reports were in systems that saw heavy use of the cabin heat.

Also, have you checked resistance/continuity of both the inside and the outside of you convector stubs since pulling things apart? There was some suggestion that the insides might be anodized based on their appearance, but at least one owner reported continuity on both surfaces.

It's interesting that your check valve looked clean. On mine, that piece is just a simple connector, at it showed the same corrosion as in other places. I wonder if the check valves in later units were properly anodized or perhaps made of some different material.

BrianZ · May 2021

CAUTION!..

03/26/2023: The heat shrink tubing referenced below has glue inside that failed on a hot convector & slipped off, releasing glycol from our system. While I continue to use it, I have added a screw type clamp to existing spring clamps at all convector-hose connections, plus glueless heat shrink tubing on our 3-way valve connection, as well as securing glycol hoses with external clamps secured to wood to prevent hoses from moving & pulling on the connection. I recommend only using heatshrink tubing without glue or only a suitable coating on the converter tor stubs.

Thank you, @BridgerSunset for your invaluable & experienced information. A heat shrink tubing seems like the easiest & most foolproof remedy, and I've found this marine product which sounds perfect for the job..

https://www.amazon.com/dp/B07FPKVMTW

"XHF heat-shrinkable tube has the advantages of good electrical insulation, good sealing, corrosion resistance and high temperature resistance. Anti-aging, tough, not easy to break."

I can just cut a piece to fit, slip it on, heat it with a butane lighter & done within a minute. Seems like this 1-inch size should be a good fit.

Thanks again for your expert opinion!

Well, I guess I may as well move on to cleaning up the remaining four connectors, so I'll be ready when the heat shrink tubing arrives. I'm going to try & return the Loctite goop. Its ingredients, by the way, are talc, quartz & isopropyl alcohol. Seems like a weird sort of paste to use for this purpose, but talc is an inert kind of mineral that is very fine, but I'm surprised it's used as a sealant. Heat resistance might be its strength.

And thanks, @Tabaz. I'm using my Samsung Galaxy Note8 phone camera. It's very capable, but I also generally take care in post-processing photos to optimize color, contrast, resize & sharpen using an Android app called "Photo Editor" which has an extensive array of tools, which I found was the closest thing to photoshop for a phone app. Downsizing often reduces sharpness, so I compensate using the unsharp-mask tool. I also have some Canon pro level camera gear, which I don't use as much any more unless the situation requires it (like shooting wildlife or night sky).

ScottG · May 2021

@Dalehelman, if you have read back through this discussion you have likely noted that all this began with a bulge in a hose that eventually began leaking as it was forced against the metal clamp. That is why I originally suggested closer inspection of your own bulges, particular the lower one which from you photo looks like it might be straining against the clamp.

I was also worried about things crumbling or breaking if I started dismantling them, but those fears were unfounded given the superficial degree of corrosion. My feeling is that if you are up to the point where crumbling is a real concern (as was the case with fstop32), than you are probably headed for a leak sooner rather than later. I'd prefer to address such an issue on my own terms and schedule, but YMMV.

BrianZ · May 2021

@ScottG, I'd say we've used the Alde maybe 15 times over the last almost-4 years, for 2-4 days each time. There may have been a few times when we used it for hot water only. The coldest temps were a couple of trips that were around 30° for a few hours one day.

The electrical resistance check is on my list for today - will let you know. The check valve appears to be at least partially mounted inside the aluminum tube. I can clearly see at least part of it sticking inside the other end when I look in the metal tube. I could not inspect the other end, as it was inside the rubber end of the whole assembly that includes the auto bleeder valve. There was a bulge there under the rubber, which I figured was part of the check valve mounted inside & I didn't want to break anything that wasn't, so left it alone. I did pull off the brass looking bleeder valve & saw nothing remarkable inside. It's all one assembly.

Dalehelman · May 2021

@ScottG
I don’t disagree with you. I plan on taking a different tack. I am hoping to arrest and stop further corrosion by eliminating water in the system. Water being the main agent for the development of our corrosion problem. I am still reluctant to break the seal between the hoses and the convectors. One reason is my ability to get into the tight areas. At 75 years old the body just is no longer up to the task. Any way if we all go the same direction. We may miss an opportunity to find an better easier way. I also feel if we were using a waterless transfer fluid we would not be having this problem at all. Unfortunately only time will tell. Check in with me on my 100% waterless coolant thread, and wish me luck as I do the same for you guys.

Tabaz · May 2021

Image: https://us.v-cdn.net/5021717/uploads/editor/ms/iq388zpv19va.jpg

Many of us are sitting in the bleachers with our foam #1 hands cheering you on Dale. The new fluid could be a game-changer.

Dalehelman · May 2021

I really have no doubt that the Evans would have prevented the corrosion problem. That is why it was developed. My hope is that it will stop the progression.

BrianZ · May 2021

@Dalehelman, that would be awesome & I sure hope it works for you. How long have you been using it? Do you use their test strips or a refractometer to check for any water? Do you know what NuCamp or Alde thinks about using the Evans fluid?

BrianZ · May 2021

@ScottG, I just checked for conductivity on all 4 pipes shown above, including between outside surfaces, inside surfaces and outside to inside surfaces, and there was conductivity pretty much everywhere I tested, except on a few spots of residual corrosion stain, which I assume were just poor contact due to surface contamination. Ohm readings were inconsistent, so I didn't record any, but typically a couple ohms or less. With conductivity, the meter was pretty much beeping no matter where I put the probes, especially on the cleanest shiny looking metal. It was one big holiday for those electrons, to use @BridgerSunset's terminology. This testing would seem to indicate there never was any anodizing.

Dalehelman · May 2021

@BrianZ
I had Evans in our Jeep for going on 6 years. Still like new 0 water.I use a refractometer to test for water. I will be sealing the one air vent on the Alde tank. Then attach a balloon to the overflow tube. That way the system will be air tight. The balloon will allow for expansion and contraction during the heating and cooling cycles, and I can see what is happening.
As for Alde they don’t seem to be much help and I doubt if they are much interested in my input. On the other hand Evans was very interested, and helpful. After all transfer fluid is their business. NuCamp I am afraid gets all of their information from Alde which is kind of a catch 22. I still think Alde is a great product, but since Spencer is no longer with them knowledgeable information is hard to get. Besides this is not rocket Science as they say Its just boilers Radiators/convectors and transfer fluid. Now the electronics of the Alde is a different thing, and that’s where the real magic is. At least for me.

ScottG · May 2021

Dalehelman said:

...
One reason is my ability to get into the tight areas. At 75 years old the body just is no longer up to the task.
...

I hear ya', Dale. Seventy-five is still a ways away for me--if I even make it I'm not sure I'll be up to the task of camping, let alone innovating and trying new ideas. Rock on, sir! ;-)

ScottG · May 2021

Thanks for the testing report, @BrianZ. Your findings on the inside match what @pak reported previously.

Did it look like there was a coating of something on the inside of the pipes? In your pics they look a little smoother than what I saw in mine, and in @fstop32's photos, which was a whitish-gray slightly textured surface. I was hoping that was anodizing, but it seems unlikely...

BrianZ · May 2021

Well, let us know how the Evan's fluid works out for you, @Dalehelman. By the way, I'm only 4 yrs behind you, so I feel those tight spaces too. That's why, today, rather than trying to bend & stretch to clean the rest of the convector pipes, I simply removed the 4 screws & took them out for easier cleaning while sitting comfortably.
This was my worst one, I think from the rear upper left near the bleeder valve (also the most difficult hose clip to slide off to the side)..

Image: https://us.v-cdn.net/5021717/uploads/editor/9x/1ypxfmf81ana.jpg

To answer your question, @ScottG, yes, some pipes had a light dusting of whitish powder near the ends of pipes with more corrosion like above, which was concentrated near the end & faded within an inch or two. I could scrape it off with a fingernail, so not as hard to remove like the corrosion above.
Here's how I used a piece of pvc pipe to scrape off the corrosion (plus a plastic scouring pad)..

Image: https://us.v-cdn.net/5021717/uploads/editor/n6/9hrz03gur6im.jpg

And I was happy at first with the heat shrink tubing mentioned previously, which I received this evening & tried out..

CAUTION!..

03/26/2023: The heat shrink tubing below has glue inside that failed on a hot convector & slipped off, releasing glycol from our system. While I continue to use it, I have added a screw type clamp to existing spring clamps at all convector-hose connections, plus glueless heat shrink tubing on our 3-way valve connection, as well as securing glycol hoses with external clamps secured to wood to prevent hoses from moving & pulling on the connection. I recommend only using heatshrink tubing without glue or only a suitable coating on the converter tor stubs.

Image: https://us.v-cdn.net/5021717/uploads/editor/xe/ppk7ku2ytpnn.jpg

I didn't realize I had a photo-bomber when I took this shot, but since today was her 6yr gotcha day, I let her have her way, as we've done all day.
Before applying heat, I extended the tubing 1-2mm beyond the end of the pipe so it would wrap around the edge for a better seal.

rh5555 · May 2021

Looks like I need to amend my earlier opinion about anodizing. If I was responsible for making these radiators, then they would have been anodized inside and out; but then it's possible that I'm a perfectionist and bean-counters (not engineers) are calling the shots here.

So my revised opinion is that Alde is using corrosion inhibitors instead of anodizing to prevent the corrosion, and it is failing around the rubber hoses because small amounts of the glycol seep in there and all the corrosion inhibition gets used up. Otherwise, as previously pointed out, called crevice corrosion.

I offer 2 options to alleviate this situation:

If you have no swelling under the hoses, use a 2nd hose clamp to grip the hose near the end of each aluminum sleeve. This might/should prevent small amounts of glycol seeping in and causing the corrosion. Cheap insurance.
If you already have swelling, then drain, disassemble, clean up and cover with heat-shrink tubing a la @BrianZ - assuming the heat-shrink doesn't increase the diameter so much that you cannot get the hoses back on.

Now I need to go explore my own TAB and find out my situation - and follow my own advice!

MarkAl · May 2021

This thread and the corrosion one's photos of not the outside but the inside is more telling to me. I'm not feeling good about the best way to protect from the problem. Since the inside of (I think) the pipes is clean it's not galvanic or PH level (though keeping it good may help). The problem as some of you have been saying is the seep under the clamps not being refreshed with corrosion inhibitors. From my limited chemistry (and rust on cars) this situation of trapped water / oxidizer is the issue. The best reason to get rid of it w/ the Evans! We're talking extra clamps, Locktite or heat shrink tubing but I'm wondering if a thick inert layer of non-polar material (thick grease) that displaces and repels non-polar water (or glycol) wouldn't be better to cover the joints with? Have no clue if the intro of even a bit of a grease or ? material would do to the glycol .... thoughts from the great ones of this forum?

Dalehelman · May 2021

IMHO removing the water will eliminate the problem. Everything else is a band aid. If you reintroduce water of any kind. The process will begin as the inhibitors start loosing their effectiveness probably beginning immediately.
This is only my opinion. Backed by Evans experience in transfer fluids.

ScottG · May 2021

@BrianZ, that last convector you showed looked like it had some serious metal being eaten away at the end--more so than anything I saw on mine.

Your description of the inside of the pipe also seems a bit different from what I observed, and what @fstop32 described. The coating (whatever it may be) seemed more uniform and more firmly bonded to the pipe (below). As I noted previously, the inside of your pipes even look different, as best as I can judge by photos.

I don't know what to make of this. The differences could be age-related, use-related, or manufacturing-related. I'm not drawing any conclusions at this point, as the evidence thus far seems to be all over the place.

Image: https://us.v-cdn.net/5021717/uploads/editor/o6/10dw6qgn6c6j.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/wf/253t4k6c3kdd.jpg

Horigan · May 2021

MarkAl said:

This thread and the corrosion one's photos of not the outside but the inside is more telling to me. I'm not feeling good about the best way to protect from the problem. Since the inside of (I think) the pipes is clean it's not galvanic or PH level (though keeping it good may help). The problem as some of you have been saying is the seep under the clamps not being refreshed with corrosion inhibitors. From my limited chemistry (and rust on cars) this situation of trapped water / oxidizer is the issue. The best reason to get rid of it w/ the Evans! We're talking extra clamps, Locktite or heat shrink tubing but I'm wondering if a thick inert layer of non-polar material (thick grease) that displaces and repels non-polar water (or glycol) wouldn't be better to cover the joints with? Have no clue if the intro of even a bit of a grease or ? material would do to the glycol .... thoughts from the great ones of this forum?

I like this idea. Just be sure to use synthetic grease so you don't deteriorate the rubber hoses.

Denny16 · May 2021

Or just clean and anodize the outside of the tubes at the hose connections, do this once, and Bob’s your uncle...
cheers

BrianZ · May 2021

Also, after cleaning the outside of our convector pipe stubs, I remembered I had some silicone conformal coating liquid, so I just painted the remaining three convectors with that before I add the heat shrink tubing to those. It's got some extremely volatile & dangerous solvents, so you have to use precautions, but it dries extremely fast (like a min or two) & is made to protect electronics from corrosion. Goes on like fingernail polish, but thinner. I used it to coat the circuit board of our Victron battery monitor, since it's mounted in the battery tub (in an enclosed box, but not protected from humidity/condensation).
So, with the pitting corrosion I've found in several places, that seemed like a good way to seal them up before the heat shrink goes on. I also saw a polyurethane spray version on amazon.

PS: if you look here & scroll down, there are descriptions of the different types of conformal coatings, depending on characteristics needed..
https://www.amazon.com/dp/B008O9YGQI

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