L35/BT900 backhoe falls

[lewiville06]

Hi everyone,
I am brand new to this site, but not new to my L35 with BT900 back hoe. I have an issue I hope someone can help me with. when I try to raise my main boom on the backhoe, it will make a click sound and then fall to the ground, unless I pull it back very slowly and gently then it will come up all the way but the more stress you put on that hydraulic ram (stick boom fully extended) the more it doesn't want to lift. Fluid levels are good and nothing is leaking. It is sort of a controlled fall, similar to putting the front loader into 'float' I can take video if that would help. thank you!

 

[Sammy3700]

This is a shot in the dark singe I thinking of a Woods 7500, the main boom cylinder on the one I had did have a float position like the loader. Puller the lever easy worked great pull it all the way it clicked into float. Hope this helps, I do not see the need for the float position.

 

[Stubbyie]

Same unit in all respects and not had happen what you describe. Not aware of any 'float'-type position in the OEM valve assembly. Also no mention in the Operators Manual.

I think you have a bad valve, perhaps a piece of junk (inner hose lining) trapped in the valve.

From your description, might somehow be a bad cylinder seal where fluid is bypassing internally.

The 'clicking' mentioned points me more toward a valve with a spring-loaded poppet jumping into / out of position.

Valves are rebuildable and can be accomplished by those inclined but I've had better luck (other machines) considering time and convenience just dropping the valve body off at a known quality commercial hydraulics shop rebuilder. I'm sort of contrary in some regards and expect an almost-clean room setting, not a guy with one flickering light over a drippy workbench that has to have a place shoveled clear to throw your valve onto the pile.

I am extremely curious what you find and the resolution of the problem.

Please post back your continuing experiences so we may all learn. I'd appreciate your efforts for my benefit and that of the Forum community.

 

[lewiville06]

Hey guys,
So I got the tractor out yesterday to do some work around my land and I wanted to remove a couple stumps but like I had said before the backhoe isn't working properly so I started digging with the loader bucket as I live in a an area with soft sandy soil, it works pretty good. I work on this for a bit and once the machine was good and warm, the backhoe works fine...I used it for about an hour no issues. I did notice that the hydraulic cylinder does in fact have a minor leak and it also settles very fast, If I pick it all the way up into the "travel position" it will settle back down to the ground in 2-3 minutes so I have to keep the locking pin in it when its not in use. Having said all of this and going off of your suggestions, I do believe it is an issue with the Cylinder and that it will need to be rebuilt. This tractor has been in the family for over 10 years and this is the first issue that its ever had but also the backhoe attachment hasn't been used for about 2 years so that probably has a hand in why its acting up. as long as the problem doesn't get worse, I may try to get by until the ground freezes, then take machine in to Kubota to have them diagnose and repair it. Whew! a little long winded but I'm glad the thing works once it is warm and I appreciate the input.

 

[Stubbyie]

Minor cylinder leak isn't that big a deal: hydraulic fluid can be cheap compared to wrestling that cylinder out of the boom.

A backhoe is nothing more than a mobile collection of current and future leaks waiting to happen.

If you pull the cylinder you'll probably need to remove the other hoses in the bundle inside the boom. Invest in a set of flare-nut crow-foot ratchet-driven wrenches (Sears best deal) and if you can spring for them a set of hydraulic service wrenches from one of the big names (mobile distributors). EBay will occasionally have a decent set available. Avoid HF in both cases as flaking chrome will slice and dice hands. WRT the service wrenches, buy quality and pass them to your kids; you can always get your money back on resale. Your life will be made much easier.

Original post didn't mention backhoe was offline for couple years. Reinforces probability that you had a sticky valve or a piece of junk worked through a valve.

Work the hoe hard then change hydraulic filter if not all fluid. Look for hose leaks on hoe especially if OEM 'fuzzy' oil soaked. Time to get those wrenches (above) ready...

And if you change one hose (assuming worn, not damaged), change them all and be through with it. Otherwise, you'll be changing hoses for the next year, one after another, usually at the most inconvenient time.

Please post back your continuing experiences so we may all learn.