Stainless steel reservoir seeps

On the one I repaired the little neck wasn't loose, just leaked. But as I heated the spot to try and seal the leak with silver solder, it melted the existing filler material and the whole neck came loose. Then I was able to clean things up better and start over. But I'm guessing the original filler material had a very low melting point, which might have something to do with why they form leaks so easily?

YIKES!!!
I'm so glad you asked this!!!
More reply to come.
PLEASE, nobody buy brazing alloy based on my above recommendation, yet.
 
Oups!
I was planning to use "The Bernzomatic MAP-Pro Hand Torch Flame" ... the yellow bottle
https://www.bernzomatic.com/Products/Fuel-Cylinders/Hand-Torch-Cylinders/MG9
I soldered a new brass barb section onto the bottom hose nipple (see this thread) using a propane torch (like what you use for plumbing), and the heat was enough to re-flow the solder / brazing between the stainless tank and the brass nipple. I think MEP would be perfectly adequate, and that oxy-acetylene would be way overkill.
 
So I looked up the specs on my butane "micro" torch. It says butane is good for 2000F according to HF and found some info by searching for "butane flame temperature" that says the common commercial butane torches reach approx 2600F, but butane in air maxes out at almost 3600F. I would assume that is with ideal conditions with excellent equipment. I am stuck with my micro torches. :)
 
I think it also depends on the thickness of the base metals that you are brazing. For soldering electrical wires I use a little butane torch. But for battery cables it does not get hot enough so I use a larger propane torch. Then I tried using the propane torch for a larger-heavier item and it never got hot enough, so I used my Oxy/Act set with a fairly small tip. So when I repaired the overflow tank I used the same O/A set up and it worked fine, but a smaller torch size (either smaller tip or a jewelers torch) would have been better. I did not try the propane on it. From what I understand (but not certain) the heat increases going from butane, to propane, to MAP, to O/A.
 
What a great write up Brian, you have summarize the most important things we must know for the silver brazing.
Sure I will apply all the hints recommendation for a success with my repair.

Can you confirm my purchase planning is correct:
From Muggy Weld
SSF-6 Silver solder https://www.muggyweld.com/product/ssf-6-silver-solder/
also
SSF-6 Flux paste https://www.muggyweld.com/product/ssf-6-replacement-flux/

The reason I'm dealing with Muggy Weld products is that he delivers to Canada.

Thank you very much for taking the time to write this document.
I'm sure the whole "X" community appreciates too.

PS. Kermit says Thank you for compliments :)

Best Regards,
Yves

Yves,

This is embarrassing... I made a mistake, running with some assumptions, and gave you some bad information. The assumption was that the parts on the existing tank were Brazed, not soft-soldered. Hussein's successful repair by brazing the joint, My chat with the folks at Harris, and the design of the joint itself all pointed me in that direction. But Jeff's comment about one coming apart unexpectedly tipped me off. I have an aftermarket Stainless tank on my car, so I examined it. Mine is definitely soft-soldered. I can slice into it with my pocketknife. It is probably an alloy similar to the "Stay Brite" (96%Sn/4%Ag) mentioned earlier. If yours is built the same way mine is, trying to Silver Braze it without first removing ALL the soft solder would have been a miserable failure.

For soft-solder to work well it needs much more surface area, like in the overlapping joint ngrandolph used to repair the outlet tube on his tank. I expect his repair will hold up, in spite of the comments from the tech at Harris.

I've got to give some thought to how best to approach the repair. Options include:
1. Just soft-solder it and give it a try. That's simple, easy, and cheap. It won't make anything worse, except for a small area of your chrome (which is unavoidable).
2. Re-design the joint, perhaps adding a piece with a ferrule & flange, to give adequate surface area to a soft-solder joint.
3. Take it apart, clean all the solder off, and reassemble it by brazing.

Again, I apologize for taking too much for granted in my assumptions. I believe that what I wrote about brazing in general is accurate, but it doesn't apply very well if the joint needing repair was soft-soldered to begin with.

Brian
 
Last edited:
I soldered a new brass barb section onto the bottom hose nipple (see this thread) using a propane torch (like what you use for plumbing), and the heat was enough to re-flow the solder / brazing between the stainless tank and the brass nipple. I think MEP would be perfectly adequate, and that oxy-acetylene would be way overkill.

The repair you did was nicely done. You gave the solder plenty of surface area by using the tube like a coupling.
Yes, Oxy/Acetylene would have been too hot for that approach, but would be an appropriate choice for brazing.
 
On the one I repaired the little neck wasn't loose, just leaked. But as I heated the spot to try and seal the leak with silver solder, it melted the existing filler material and the whole neck came loose. Then I was able to clean things up better and start over. But I'm guessing the original filler material had a very low melting point, which might have something to do with why they form leaks so easily?

Brian, I imagine you have a small "jewelers" style torch you use for your O/A kit?

Jeff, Thanks again for your post. Sharing your experience made me question my assumptions and led to better information.
I'm suspecting that the filler material you encountered and that on the tank in my car is something very much like Stay Brite. Since the design of the joint provides so little surface area, I think it would be prone to failure. The bond that brazing would provide is roughly 3X
stronger with the same surface area.
I use many different torches. The two that I use most frequently are called 'National 3A Blowpipes', with several different tips. The one for silver brazing runs on Natural Gas and bottled oxygen. The one for soft-solder runs on Natural Gas and compressed air. These aren't setups that many people other than instrument technicians would have or even want. But, since you asked, there it is.

Brian
 
So I looked up the specs on my butane "micro" torch. It says butane is good for 2000F according to HF and found some info by searching for "butane flame temperature" that says the common commercial butane torches reach approx 2600F, but butane in air maxes out at almost 3600F. I would assume that is with ideal conditions with excellent equipment. I am stuck with my micro torches. :)

The butane micro torches are handy for a lot of things. They are adequate for small soft-soldering jobs. Even some TINY brazing jobs. The 'Swirl'-type Bernzomatic Torches with a MAP gas cylinder will do some reasonably sizable brazing jobs, and they aren't too pricy for an occasional-use tool. It all depends on what you want to do. I was suggesting Oxy/Acetylene to Yves specifically to help minimize damage to his Chrome, by letting him get in and out very quickly. But now I think that was all based on a faulty assumption about the existing filler material..

Brian
 
Brian, your initial impressions about the type of joint (brazed vs soft solder) may not be totally incorrect. Apparently there are at least two different stainless steel overflow tanks out there; one was a factory issued item (I believe for only 1 year?), the other a aftermarket reproduction of the factory unit (someone please correct me if I got that wrong). I have three of these S/S tanks, one factory item and two aftermarket items. The factory one is much older than the other two and has never leaked, it's joints are still solid. The other two both developed leaks at these joints. I do not know how to tell for sure, but it might be possible the aftermarket items are indeed soft soldered but the factory ones are brazed. I'll have to dig all of them out and look closer. I vaguely recall the older factory one might have more of the yellow "bronze" color at the joints. You say the soft solder joints can be impressioned with a knife blade?

Your discussion about various torch types supports the experiences I've had with different attempts at soldering/brazing.
 
Yves,

This is embarrassing... I made a mistake, running with some assumptions, and gave you some bad information. The assumption was that the parts on the existing tank were Brazed, not soft-soldered. Hussein's successful repair by brazing the joint, My chat with the folks at Harris, and the design of the joint itself all pointed me in that direction. But Jeff's comment about one coming apart unexpectedly tipped me off. I have an aftermarket Stainless tank on my car, so I examined it. Mine is definitely soft-soldered. I can slice into it with my pocketknife. It is probably an alloy similar to the "Stay Brite" (96%Sn/4%Ag) mentioned earlier. If yours is built the same way mine is, trying to Silver Braze it without first removing ALL the soft solder would have been a miserable failure.

For soft-solder to work well it needs much more surface area, like in the overlapping joint ngrandolph used to repair the outlet tube on his tank. I expect his repair will hold up, in spite of the comments from the tech at Harris.

I've got to give some thought to how best to approach the repair. Options include:
1. Just soft-solder it and give it a try. That's simple, easy, and cheap. It won't make anything worse, except for a small area of your chrome (which is unavoidable).
2. Re-design the joint, perhaps adding a piece with a ferrule & flange, to give adequate surface area to a soft-solder joint.
3. Take it apart, clean all the solder off, and reassemble it by brazing.

Again, I apologize for taking too much for granted in my assumptions. I believe that what I wrote about brazing in general is accurate, but it doesn't apply very well if the joint needing repair was soft-soldered to begin with.

Brian
There are only the people who get involved that can make mistakes, he sure that if we do nothing we do not get things done.
If this is the worst thing that happened to me today, everything is fine there is no problem.

Brian do not be embarrassed:) Your advice is relevant.

Yves
 
... These aren't setups that many people other than instrument technicians would have ...

Wow, to me "instrument technician" would mean something totally different...making a living building musical instruments, now that is cool.

SteveC
 
Funny we have at least two, Mr Ranney (aka FiatPower) in Vermont is also an instrument technician.

Wow, to me "instrument technician" would mean something totally different...making a living building musical instruments, now that is cool.

SteveC
 
Funny we have at least two, Mr Ranney (aka FiatPower) in Vermont is also an instrument technician.
I bought a passenger-side mirror from Jon a couple years ago, that I picked up from him at a conference for Band Instrument Repair Technicians. It's good to get together with a couple hundred horn-techs to have a chance to talk about the kinds of things nobody else cares about... Kinda like a Freakout..
Brian
 
This might be too different to apply here, but how much of this soldering/brazing information would apply to repairing aluminum radiators?
 
This might be too different to apply here, but how much of this soldering/brazing information would apply to repairing aluminum radiators?

IMO Welding would be required. There is a low-heat (propane torch) aluminum braizing rod, it sucks & is a royal PITA to use on aluminum pipe, never mind such a large heat soak as a radiator . I did use it before I bought my TIG setup. It is an exercise in frustration.
 
I watched my Dad braze and solder alloy / aluminium a few times when I was younger... I've never been able to get the hang of it... strangest thing I thought about the process was he used Tallow (like a rendered animal fat) as the flux or to help it flow... he used this process to weld alloy body panels (on a few exotics like his Alfa GTA) back when I was a very young child.

Russell, I'm going to share that with my little brother (a Ferrari owner / lover) ... that is classic!

SteveC
 
I disassembled & brazed my coolant tank to verify that the process I described is good. I took some photos along the way, to share. I couldn’t figure how to integrate them into the text, so they are all attached at the end.

First, I verified that what was on my tank really was a soft-solder. My opinion is that soft-solder is inappropriate for this application, (especially with as little surface area as provided by the type of joint) and is likely to fail. One way to test is whether you can cut into it with a knife relatively easily. That’s all the first image is intended to show.

Once that was established, I disassembled the parts that were soldered in; neck, inlet, & outlet, and cleaned off all the old solder. Heat it up until just molten and wipe with a paper towel to get the bulk of it. Then use abrasives to clean off the rest. It’s very important that all that is completely G-O-N-E, as any residual soft solder will interfere with the brazing.

I didn’t like the way the inlet tube shot the returning coolant down into the tank. It seemed that it made the coolant foam more than in the plastic tank, where the inlet is directed against the back wall of the tank. So I made a replacement part. That process would take a lot of explaining, and it’s not part of fixing the leak so I’m not elaborating right now. The third picture shows the two parts.

I re-fit the neck so that it sat flush on the surface of the tank. The fourth picture is an ‘action shot’ brazing it in. The flux, filler, and torch are as noted in earlier posts.

After the joints are cool, soaking in a phosphoric-acid solution will remove the residual flux and fire-scale, but there will still be a lot of discoloration. That has to be removed abrasively. The final picture shows the end result.

I hope that helps, if anyone want to approach fixing a leaky tank this way.
 

Attachments

  • IMG_6492.JPG
    IMG_6492.JPG
    214.5 KB · Views: 163
  • IMG_6494.JPG
    IMG_6494.JPG
    250.7 KB · Views: 152
  • IMG_6496.JPG
    IMG_6496.JPG
    195 KB · Views: 155
  • IMG_6507.JPG
    IMG_6507.JPG
    261.1 KB · Views: 158
  • IMG_6508.JPG
    IMG_6508.JPG
    251.3 KB · Views: 161
  • IMG_6509.JPG
    IMG_6509.JPG
    230.8 KB · Views: 159
Last edited:
Back
Top