Hydraulic line too thick?

[weedsportpete]

I'm not sure if I should post this in Hydraulics or Kubota...

On my BX2200, the hydraulic line that loops between the first and third hydraulic fitting on the right side of the tractor is leaking, at the third fitting. The leak appears to be coming from between the sliding sleeve and the fitting going toward the tractor.

Anyway, this is the third time I've had a leak in this fitting. The first time I took it to the dealer and aside from replacing the fitting, they also replaced the line going from the first coupler to the third coupler. The replacement line was thicker than the original. They assured me that thicker was better, stronger, faster, etc.

In my own uninformed mind I see this newer hose thickness translating into more stiffness, and that the tight curve of the hose between the first and third couplers is applying more pressure to the third coupler fitting, in the direction perpendicular to the line of flow, i.e. the hose is bulging outward toward the front of the tractor. And this continual pressure is bending or at least stressing the fitting, to the point where it eventually fails.

The hose was replaced almost four years ago. Since then this fitting has leaked twice. Once my neighbor helped me replace the coupler fittings, which worked for about a year, and then last year it leaked again in the same spot and I brought it back to the dealer and they replaced it, last November. 400 hours later, it is leaking again, same spot. It started after I had the loader on and worked it continually for two hours. The next morning I took off the loader and it started leaking immediately. Not a lot, but steady little drips.

I made a crude clamp out of metal that slips over the loop of the hose and it pulls the hose together into a tighter loop and that completely stops the leak.

ok, so after all those assorted facts and theories, does anyone have a strong opinion on whether the hose could be to thick (too stiff) for that application, i.e. is exerting too much pressure for the coupling/fitting?

Thanks,
Pete

 

[J_J]

I think that I would take a picture of the hose on the tractor. I would then take it to a hydraulic shop and tell them your story, and let them come up with a solution. Then ask them if they will guarantee it against leaking from the hose and the crimp. You only need to know your max pressure.

 

[skipperbrown]

I have a bx2200 too w/ 480 hrs. I've never had problems w/ the couplers but all the hoses on the tractor including power steering have failed at least once. I think Kubota got a bad batch of hose on my production run.

I also had a tube leak at the metal clamp that holds the 3 lines as they exit from beneath the tractor.

After finding that my Kubota dealer stocks almost nothing for a bx, I went to aftermarket hoses and they seem to be superior to the OEM hoses. The replacements are the same diameter as the original or at least I couldn't tell any difference. The cost was better too.

My feeble mind thinks that metal trumps hose in all fights. I'm surprised the way-too-tight hose loop isn't the first failure point on your tractor. I find it hard to believe a bent hose could torque a metal fitting to failure. On the other hand, I can't believe my mother lied about the tooth fairy.

 

[kennyd]

On the other hand, I can't believe my mother lied about the tooth fairy.

Crap, you mean the tooth fairy isn't real either just found out about Santa Last week What next...the Easter Bunny

 

[Wayne County Hose]

You would be surprised how much force a hose can take over steel. I've seen cylinder housings split before the hoses connected to it blew.

Sounds like you need to replace that hose. Call around to local hydraulic shops. Ask them if they stock 100R16 hose. This is 2 wire hose very similar to the common 100r2 2-wire hose except that it has half the bend radius and is way more forgiving to surges and flexing. I would also make the new hose as long as you sensibly can. When fluid goes thru the hose, it tries to straighten. When it does that, it torques the fitting. A longer loop will spread the flexing. I have found dealers to not have a very good understanding of hoses, of course, there are exceptions. They all tell you theirs is the best, because that's what they want to sell you. If you ask them to explain why theirs is better, uh-oh, the famed deer-in-the-headlights 1,000 yard stare.

 

[weedsportpete]

Thanks guys
JJ, Wayne County Hose - I think I should take it to a hydraulic shop. At the very least it will give me peace of mind after seeing three failures in the same spot, and hopefully it will be cheaper than what the dealer will want to do. And if it doesn't fix the leaks, then it must be the fittings. But I won't be going back to the dealer.
skipperbrown - we both have had line failures on the bx2200; sounds like my dealer opted to go for a more heavy duty replacement. The jury is still out on it being a cause of the subsequent leaks.
kennyd - good thing we can all still believe in the Great Pumpkin..

Pete

 

[weedsportpete]

I took it to a hydraulics shop. He said it was not the hose. Either I have been too rough with it or let dirt get in the coupling. He recommended I change both male and female ends. I'll try that, and be more careful when changing lines, and see what happens.

Pete