BH75 Hoses a popin !

[riprap]

Well, After deciding that the connectors on the extension were the problem, I replaced the hose, removed the extension and went back to work....

And had ANOTHER hose blow out ! (after about 30 min of work)...

So, at this point I was sure it must have indeed been the relief valve (haven't received the JIC adapters need to measure pressure yet) - the hose was again in the swing circuit - so far 3 out of the 4 swing circuit hoses have failed....

So I backed the tractor into my garage and started to remove the hoe (I bypasses the swing circuit to stop the leak) - then all of a sudden I had a new leak from somewhere !... It turned out to be from the right side stabilizer - and on further inspection... the (retract) hose had blown also !

Now I was really stumped - the stabilizer doesn't even have a relief, much less the retract side - which never sees any pressure except when the stabilizer is at the top of travel....

I decided to cut into the hose where they blew out to see what the steel reinforcement looked like - (pictures below) - it looked corroded to me, so then I cut open a part that was OK, it looked like normal shiny steel. Then I inspected the hoses carefully and noticed that there were some lumpy areas - so I cut these open as well - and found a bunch of rust under the rubber outer layer !

So the problem is not relief pressure - it is that in at least 2 circuits, there is corrosion inside the hose reinforcing steel, causing them to lose strength.


I can't really imagine how this happened - the hoses are not damaged from the outside (the blow outs/rust areas) are not subject to any abrasion and the hoe has only been used a few hours. The hoe was bought new and used for a short time, then stored indoors for the last few years. The hydraulic fluid over that time was what came in the tractor new, after being removed the hydro hoses where plugged into each other...

Even if there was some moisture in the lines - I would have thought that there was rubber on the inside of the lines, embedding the steel, not leaving it exposed directly to the fluid...

SO- bottom line I inspected th hoses as best I could and found damage to all of the swing circuit lines (the last unfailed one) and both lines to the right side stabilizer. So far as I can tell (not very well) the lines to the working cylinders seem to be ok.

Next step is to get 4 more new lines and see what happens next.

Anyone ever seen anything like this ?

Also for anyone interested the differences in the QC tips - doesn't seem to be a problem...

 

[Egon]

It may be advisable to replace all the original hoses.

 

[CHDinCT]

Sounds like you're making headway on the issue but I'd still want to check the relief pressure when you have the new hoses installed. You might also consider changing out the hydraulic oil given the rust that may have entered the system. Hope your pressure issue is solved with the new hoses.

 

[riprap]

I dissected some more hose while waiting for more of the long 90 3/8 JIC to 1/4 hose ends to come in. I made some cuts across the rust bulges where the hose has not failed and it looks like both the inner and outer rubber is intact - so I am unsure of where or how the corrosion is happening.

The backhoe was last on the tractor when it was new, and the hydro oil was changed since then. It is really strange, there is no rust at all on the hoe, having been stored inside an unheated shed for the past 4 years, yet these hoses are rotting even though new in 2005.

I have had all kinds of equipment over the years, most quite old and abused with hoses old as heck and I never saw anything like this.

Just goes to show how true it is that leaving machinery idle is the hardest on it.

 

[RobKinNH]

I dissected some more hose while waiting for more of the long 90 3/8 JIC to 1/4 hose ends to come in. I made some cuts across the rust bulges where the hose has not failed and it looks like both the inner and outer rubber is intact - so I am unsure of where or how the corrosion is happening.

The backhoe was last on the tractor when it was new, and the hydro oil was changed since then. It is really strange, there is no rust at all on the hoe, having been stored inside an unheated shed for the past 4 years, yet these hoses are rotting even though new in 2005.

I have had all kinds of equipment over the years, most quite old and abused with hoses old as heck and I never saw anything like this.

Just goes to show how true it is that leaving machinery idle is the hardest on it.

Get the mfr name off the hoses and do a search. They might have had a bad batch of the steel reinforcement. They might even offer a replacement hose at a reduced cost.

 

[Egon]

Pin hole in outer covering, expansion , contraction, condensation.

 

[workinallthetime]

b3030 tlb 200+ hours. bh75, la403
i boke a BH hose at 15 hours within a month of purchase, since then i have replaced 4 hoses due to spontanious combustion i say. i think kubota didnt do a real good job on these or their supplier was the cheepest bid that year. I would have to admit im a little worried a hose will blow and shoot it the fluid into my eye, or cause me to drop a load "no pun intended".
i replace all mine with ones from a shop around here and those have yet to fail.

 

[riprap]

b3030 tlb 200+ hours. bh75, la403
i boke a BH hose at 15 hours within a month of purchase, since then i have replaced 4 hoses due to spontanious combustion i say. i think kubota didnt do a real good job on these or their supplier was the cheepest bid that year. I would have to admit im a little worried a hose will blow and shoot it the fluid into my eye, or cause me to drop a load "no pun intended".
i replace all mine with ones from a shop around here and those have yet to fail.

What year is your rig ? mine is a 2005

which hoses failed for you ?- same type of failure as I see - a blow out in the middle of the hose somewhere ?

For me the clincher was the stabilizer hose that raises the leg blowing - not exactly the most demanding part IMO.

 

[J_J]

This is my answer.

You can see where the hose has rubbed down to the metal.

http://www.tractorbynet.com/forums/hydraulics/221324-any-hydraulic-hose-experts-seen.html

You can set the relief lower on the BH, but never higher, because the PRV will control the system pressure.

Both reliefs can be set equal.

Has either relief been tested?

Someone may have cleaned the hoses with a chemical that made the rubber brittle.

 

[riprap]

This is my answer.

You can see where the hose has rubbed down to the metal.http://www.tractorbynet.com/forums/hydraulics/221324-any-hydraulic-hose-experts-seen.html...

Someone may have cleaned the hoses with a chemical that made the rubber brittle.

Thanks, however, you are mis-interpreting the photos -

The hoses are not rubbed down, what you see in the pictures is where I cut away the covering to see what the steel looked like - shiny in normal places and full of rust where the cover was bulged. The Hoses/Hoe were bought new in 2005, used only a tiny amount and then stored. The hoses are not brittle, look new, and have no wear on them at all. The hoe was never washed.

I will check the reliefs, but considering even the stabilizer raising hose failed, it is surely not a pressure problem. These hoses have a 12,000psi burst pressure - to have 5 blow out on very light use is impossible - hence it is clear that the problem is corrosion.

The question is how it happened and is there any countermeasures called for.