Leaking hydraulic line and silver brazing

[volp]

The hydraulic tube to the 3 point linkage started leaking oil at the banjo fitting under the pump on my B6001 (with a D950 engine). I found a small crack. Replace the whole tube or repair?
After some time on the net I decided to silver braze it. Last time I did this was fifty years ago! First I found silver rod and flux on Ebay. the rods were AMC Ag130 with 30% silver and melting point 750C and the flux was Easy-flo.
Had some fireproof bricks which I placed as a small open furnace to minimize heat loss. Solved some of the flux in water and covered the crack after first cleaning it. Heated it with a butane gas burner until the flux melted and then some more. Tried to heat indirectly. Then put the rod to the tube and it melted nicely. It was then easy to cover the crack. You can remove the rest of the flux by soaking in hot water for at least 30 minutes.
The whole process was easier than I remembered!
The tube tested OK afterwards.
I found a few tips on the net here and here, There are more on Youtube

 

[Bulldog]

Nice fix, looks good.

 

[ShaunRH]

Brazing will likely not hold significant pressure over the long haul. It certainly is a viable field fix but the flexing of the base metal against the braze material might create paths and weaknesses in the repair.

I don't know what the loads it's carrying are but you might want to save up your nickels and dimes to get a replacement part as soon as you can afford it.

 

[volp]

Brazing will likely not hold significant pressure over the long haul. It certainly is a viable field fix but the flexing of the base metal against the braze material might create paths and weaknesses in the repair.

I don't know what the loads it's carrying are but you might want to save up your nickels and dimes to get a replacement part as soon as you can afford it.

Is it really a fact that silver brazing won’t take high pressure?
I think I wait for a final verdict from Wolfman (I am howling for you!)

Anders

 

[Tooljunkie]

Its been a common repair for a long time, brazing as well.
The issue of crack re-breaking is something you should expect.
Tig may be the latest type of repair that would offer some longevity.

If you knew what caused crack in first place and have corrected it then repair should last a long time.

 

[ShaunBlake]

Is it really a fact that silver brazing won’t take high pressure?
I think I wait for a final verdict from Wolfman (I am howling for you!)

Anders

I'm not Wolfie; nor do I wish to contradict Shaun -- I'm a total rookie! I have read up on silver soldering in preparation for a hydraulic upgrade on my B6100. My reading and advice from NIW is that silver solder of 15% or more will provide adequate strength for the low-pressure hydraulics (~3000psi) on our tractors.

Strength of the weld material is of primary importance, and surface prep is a very close second, followed so closely by proper welding technique (heat the metal, not the solder) that my idea is that it's impossible to leave one out.

The test is to observe the repair under load and not see any hydraulic fluid. In that case, "Sit back and enjoy a cold one, you've earned it!" -- Stumpy Nubbs.

After a few hours of operation without seeing any leaking, I'd suggest that you put the gas and solder away and try to think of how to invest the krona you saved.

 

[North Idaho Wolfman]

Brazing / welding with hard silver solder (silver bearing brazing rod) not electric, plumbing soft silver solder is actually a very good and cheap way to repair that fitting.

The silver brazing more flexible than the metal ring an pipe thus it reduces the chance of cracking at the joint.
This method of repair is also good up to 5kpsi or better of pressure so it's well beyond the working pressures of that system.

Volp,
Is that repair on the high pressure (small line) or the larger of the two, the suction line?
Doesn't really matter as both pipes would be fine with that type of repair.

If for some reason it does leak or fail your not out a ton of money for the repair.

 

[volp]

Thanks Wolman and others!
Now I can relax.

Anders

 

[ShaunRH]

It's not about it holding the pressure immediately. I have seen this kind of repair done and last for a year and a half on a hydraulic system. The steel is what gives as the crack continues down the steel and when it gets near the edge of the braze it fails. The braze is more flexible than the steel, so the steel is the weak spot here.

It may be just fine if the line is not subjected to much vibration or movement. The more movement and vibration it is given (what broke the steel in the first place?) the greater the stress.

I'm not saying it can't last, I'm saying use the time you have with what you have to save up to replace the part if it's a money thing. That's just me though. I try not to treat field repairs as permanent ones. My father, on the other hand, loves doing just that. He'll slap his hand on a fix, proclaim "Good as new" and we'll be fixing it again in two hours or two weeks.

It's up to you and how you like to work with your equipment.

 

[nickelplated5s]

The silver brazing info was great but Shaun is right too. That is unless you drill a hole at the end of the crack.

 

[ShaunRH]

The silver brazing info was great but Shaun is right too. That is unless you drill a hole at the end of the crack.

That is the proper fix Nickelplated.
(It's strange to think that drilling a hole into something that holds pressure is ever a desired thing to do though... )

 

[volp]

Thanks for all the input.
As I saw it, the crack was located at the junction of the steel pipe and the banjo fitting. My guess is that vibrations is the cause.
If it leaks again I will probably replace the steel tube with a high pressure hose, with banjo fittings, to remove the vibration issue.

Anders