SLS pipe leaking - repair options?

[JOEPRO]

On my 1989 Merc cossie - one self levelling suspension hard line is leaking.



I think the part is NLA or if available sites are showing a price of £225+!

I am thinking of remaking that section with 5/16 Kunifer. The old steel tube is measuring around 8mm OD so thats very close in size.

For banjo fittings can they be bought bare and maybe braze it onto the Kunifer? Silver solder from a google?

 

[Bornfree]

You can get hydraulic banjo inserts. They will be a bit long but you could cut them down

 

[mr haynes]

Look closely at the banjo specs.
The sizing i.e. bore sizes can be all over the place.
Banjo bolt size is the easiest bit.

 

[Turbo]

What about a short hydraulic hose with a suitable banjo swaged on and on the other end a fitting to join to a brakeline type swaged flare you form on the kunifer pipe.

 

[500e]

What about Goodrich they will have a fitting to suit 99% . SS armour
The less joints the better

 

[Turbo]

Another thought, what about a standard rubber brake hose? There are many cars that use banjo fittings in their brake system.
Or you could make your own using aeroquip fittings.

 

[jo1010]

Tricky. Joining those pipes in a 2000psi system has to be spot on - solder definitely not. Brazing with the right fittings maybe - the consequence of getting it wrong would be something like an explosion.

Mostly should use flare type compression connectors in the pressure line - maybe ordinary compression fittings in the return though.

(is there no other Merc model that you can borrow parts from?)

 

[DanZac]

For banjo fittings can they be bought bare and maybe braze it onto the Kunifer? Silver solder from a google?

Does it need soldering / brazing. You can get banjo to AN3 flare easily enough (so there will be other options).

Pardon our interruption...

 

[addjunkie]

What about Goodrich they will have a fitting to suit 99% . SS armour
The less joints the better

Just make it up with stainless instrument tubing and fittings from Parker, or swagelok etc

 

[JOEPRO]

Thanks all, some great advice there!

Re the pressures and as its a restoration to a collectable car I will try to remake the pipe in metal and not hoses. Also, I would fear hoses impacting on the shock absorber function creating an imbalance between sides.

I will cross my fingers later and see if I can undo both banjos without damage. Then ill see if the hose nut undos and measure the banjo fittings. I like the flare banjo idea the most and use Kunifer lines painted black.

 

[tom2207]

Tricky. Joining those pipes in a 2000psi system has to be spot on - solder definitely not. Brazing with the right fittings maybe - the consequence of getting it wrong would be something like an explosion.

Mostly should use flare type compression connectors in the pressure line - maybe ordinary compression fittings in the return though.

(is there no other Merc model that you can borrow parts from?)

why would it be like an explosion ,,,, thats got me curious ,,,

 

[tom2207]

you can do it with stainless pipe , and braze the fittings on if compression fittings wont fit due to space constraints ,,,, if you did have to make them up in rubber you wouldnt notice any odds , I do ace pipes on land rovers frequently front ace pipes were no longer available a while ago , we had a customer source a set in japan and was looking into shipping them ,,,, two hydraulic hoses , made in 4 parts to enable fitting sorted out the issues.

 

[JOEPRO]

 

[tom2207]

is that a rubber hose with just that last bit in solid hose . the bit on the very left looks like hose , or is it a cover over a metal pipe ....

 

[indykid]

Tricky. Joining those pipes in a 2000psi system has to be spot on - solder definitely not. Brazing with the right fittings maybe - the consequence of getting it wrong would be something like an explosion.

Mostly should use flare type compression connectors in the pressure line - maybe ordinary compression fittings in the return though.

(is there no other Merc model that you can borrow parts from?)

While I appreciate your concern on gut feel, it feels a touch sensationalist in the context of some maths (also 200 bar is knocking on 3000psi).

Google reckons silver solder will develop somewhere between 70 and 250MPa in shear depending on silver content. Feels about right, so assume worst case, but consider both. Assuming an 8mm OD pipe and some decent high silver solder, that means you need a joint length somewhere between 1.6mm and 5.7mm. That's to react 200bar, which exceeds the 190bar PRV set pressure, not the 50bar normal operating pressure.

I'd be quite confident of making a fully wetted 8-10mm long silver solder joint, but if you're concerned, make some test pieces and section them to make sure you can do it repeatably.

Standard disclaimer - this is merely opinion, not advice.

 

[JOEPRO]

is that a rubber hose with just that last bit in solid hose . the bit on the very left looks like hose , or is it a cover over a metal pipe ....

Ill try removing it shortly and show the whole section. It is solid pipe from banjo pictured, to a rubber (steel lined) hose then a final short section metal and banjo joint at the top of the shock.

 

[mr haynes]

Think i did similar on a w123, but it was some time ago so can't quite remember.
Anyways, the sort of relevance, I had to manufacture power steering transfer pipes, this involved soldering kunifer.
Over a year later, no issues.
Make of this what you will......

 

[tom2207]

Ill try removing it shortly and show the whole section. It is solid pipe from banjo pictured, to a rubber (steel lined) hose then a final short section metal and banjo joint at the top of the shock.

same as lr , clean it up well and there may only be a pin prick in the pipe ,,,, Ive brazed them up before today

 

[JOEPRO]

Much better photos now its removed. It looks like both end fittings were brazed from new? And while pitted those fittings are pently strong to go again.

Can I "un braze" them or will I have to dremel them out?

I have the correct size Kunifer on the shelf and a proper Ridged brand bender for it. So this could be an ideal repair if it works out that I can braze the original fittings back onto a new Kunifer pipe section.

 

[JOEPRO]

I have not brazed anything beforw

Does this look OK or what do I need please? I have a mini oxy gas torch set and a rothenberger superfire 2 MAPP torch.

Would MAPP do it?



@doubleboost what do you braze with please? Can brazing be undone to remove the old fittings? Maybe add more fresh braze to help loosen the joint and pull them apart?