Repairing metal hydraulic line

[J_J]

I see more than one choice here.

Remove the part and take it to someone that does this for a living.

Remove the part, and clean all the fluid out and let dry, and then weld.

Cut and install unions.

I would not weld with fluid in the lines, as the carbon flakes might cause trouble in some components such as relief valves, spools, etc.

 

[Karl2]

I had one of the steel hydraulic lines on my JD 4720 burst. It's one of the 4 lines that run underneath the cab from the hydro pump to the quick-connect couplings where FEL hoses are connected. I wasn't overly surprised when the one and only local JD dealership told me they had to order replacement lines from Japan and that it would take "at least 30 days", I suspect quite longer... dunno why they do that, the 4720 is a common and current tractor, not an exotic antique...

Anyway I needed this fixed within a couple days, can't clear snow without a working FEL. Went looking for a steel union compression fitting, only to find that the pipe's 9/16 OD is non-standard and no fitting would fit it. Not willing to pay a machine shop hundred$ to have one made to order and having already (and stupidly) cut off the 2" length of pipe that was damaged I had to resort to my imagination for a more or less permanent fix. At first I thought of using a 5/8 ID short length of thick copper pipe (I used copper because brazing steel to steel with propane is difficult), just slide it over both ends of the steel hose and silver-braze it. But then I figured 2500 PSI would perhaps stress the brazed joints over their limit. So instead I used 7/16 OD copper pipe that I inserted inside the steel line and brazed it. To my amazement this worked well. Some would think smaller diameter pipe would restrict the flow rate but so do couplings so I figured it was safe.

 

[CJONE]

I had one of the steel hydraulic lines on my JD 4720 burst. It's one of the 4 lines that run underneath the cab from the hydro pump to the quick-connect couplings where FEL hoses are connected. I wasn't overly surprised when the one and only local JD dealership told me they had to order replacement lines from Japan and that it would take "at least 30 days", I suspect quite longer... dunno why they do that, the 4720 is a common and current tractor, not an exotic antique...

Anyway I needed this fixed within a couple days, can't clear snow without a working FEL. Went looking for a steel union compression fitting, only to find that the pipe's 9/16 OD is non-standard and no fitting would fit it. Not willing to pay a machine shop hundred$ to have one made to order and having already (and stupidly) cut off the 2" length of pipe that was damaged I had to resort to my imagination for a more or less permanent fix. At first I thought of using a 5/8 ID short length of thick copper pipe (I used copper because brazing steel to steel with propane is difficult), just slide it over both ends of the steel hose and silver-braze it. But then I figured 2500 PSI would perhaps stress the brazed joints over their limit. So instead I used 7/16 OD copper pipe that I inserted inside the steel line and brazed it. To my amazement this worked well. Some would think smaller diameter pipe would restrict the flow rate but so do couplings so I figured it was safe.

Actually your 9/16 tube is 14MM. This should help in getting a couple of compresion fittings and a piece of tubing to fix it if you need to. Sounds like what you did is working. I brazed many steel lines with good sucess over the years. Copper, well not for hydraulics so I can't comment on that. CJ

 

[90cummins]

Look up Swagelok, they make compression fittings that will handle the high pressures in hydraulic systems.
With a couple unions & section of tubing you can easily replace the bad section.

 

[Karl2]

Look up Swagelok, they make compression fittings that will handle the high pressures in hydraulic systems.
With a couple unions & section of tubing you can easily replace the bad section.

Thanks, will have a look at that. Good steel unions is what I'd like. Compression would be practical because brazing at sub-zero temps is unpleasant but will manage if I have no choice.

@CJONE I used thick-walled copper piping and because it is only 3 inches long and inserted inside the steel pipe at both ends it's sturdier than copper on its own. I would not use copper if the repair requires more than a few inches of pipe or pressure is above 3000 PSI. I have seen some guys use plumber's flex tube (the kind used to fill toilet tanks) as temporary fix but personally I would not trust something as flimsy as that. Oddly enough toilet hoses are rated 2600 PSI but still...

 

[Soundguy]

Look up Swagelok, they make compression fittings that will handle the high pressures in hydraulic systems.
With a couple unions & section of tubing you can easily replace the bad section.

i've used them... they work great. used them on a PS setup and unioned to existing hard lines that had cracked off at a fitting..

 

[CJONE]

Thanks, will have a look at that. Good steel unions is what I'd like. Compression would be practical because brazing at sub-zero temps is unpleasant but will manage if I have no choice.

@CJONE I used thick-walled copper piping and because it is only 3 inches long and inserted inside the steel pipe at both ends it's sturdier than copper on its own. I would not use copper if the repair requires more than a few inches of pipe or pressure is above 3000 PSI. I have seen some guys use plumber's flex tube (the kind used to fill toilet tanks) as temporary fix but personally I would not trust something as flimsy as that. Oddly enough toilet hoses are rated 2600 PSI but still...

It is working for ya, that is what matters for now. You would be amazed at the amount of 300psi malable stuff I see on high pressure hydraulics. SCARY. We use and sell Swagelock stuff here but it is pricey. The standard bite type compression fittings will work also. Lenz has fittings that have o-ring backup for sealing on compression fittings. 14mm will be a little hard to find, you may have to order it but that should not be a problem. The compression is going to be the fastest and simplest way to permanantly repair. CJ

 

[Karl2]

It is working for ya, that is what matters for now. You would be amazed at the amount of 300psi malable stuff I see on high pressure hydraulics. SCARY. We use and sell Swagelock stuff here but it is pricey. The standard bite type compression fittings will work also. Lenz has fittings that have o-ring backup for sealing on compression fittings. 14mm will be a little hard to find, you may have to order it but that should not be a problem. The compression is going to be the fastest and simplest way to permanantly repair. CJ

I looked up Swagelok, looks like very high-quality fittings. Called the one and only distributor in my state (in Bangor) and while they did not have what I need on hand they told me that if I didn't mind ordering from Canada the much larger distributor in Quebec City could rush it overnight. Nice, but I'm not in that much of a rush and it wasn't cheap with the fees and currency exchange. Drove several miles over a rough road and cleared large frozen snowbanks from a sizeable parking lot today and my copper "union" did not fail despite agressive use of a large and heavy snow bucket.

I believe that if the brazing is done properly this can hold pretty much forever, or at least for the winter. Best way to do it is to remove the whole line from the tractor so that it can be held vertical when brazing. After applying a ring of wire silver solder (electrical type is best for this method) and generous blob of paste I just heated the steel pipe with a blow torch until the copper pipe inside heated to the solder's melting point, and gravity flowed it over the joint.

One good thing about copper is that it's somewhat pliable which is useful in situations when replicating the exact shape of the original steel line is tricky. Copper "gives" enough to force couplings into place. With a steel union the job would have to be done without removing the steel hose from the tractor, so a compression union would be far more practical than a brazed joint.

 

[Older generation]

One of the main metal hydraulic lines on my JD755 that run the length of the tractor above the drive shaft has a small hole wore through it (another story).

Instead of having to try and replace the entire line (I'm not even sure I can find a replacement for it) has anyone tried repairing a hole with MarineTex?
I know MarineTex is rated to 2300 PSI shear strength and 8,700 PSI compressive strength, so I'm thinking that may contain the leak.

Any other suggestions on repairing this type of leak without replacing the line?

Thanks in advance.

Did you try the Marine Tex? Did it work? Interested, I have same problem.