Backhoe So the backhoe worked great for 12 hrs.

[Bing187]

Hi all,Bought a new B3300SU in October. Haven't had as much time as I'd like to play, but have used backhoe and loader a little. Sunday I used the hoe to dig out a big tree stump, and it worked great. Used loader for a while grading things off. Went back to use the BH, and had zero pressure when operating the dipper stick towards the tractor. It would only drop by the weight of the bucket, if put down to the ground, it wouldn't work at all. All other BH functions work perfectly, including the dipperstick if extending away from tractor. I'm guessing a bad seal in the piston, or a valve on the controller. Anyone run into something like this? Norfolk came and picked up the tractor w/out complaint, warranty will cover, I'm just curious to know before Friday....

Thanks in advance,

Mike

 

[wmonroe]

Just saw your post. Any word on what went wrong?

 

[Bing187]

Well......

Norfolk Power dropped off my B3300 on Friday afternoon. Guy took it off the flatbed, and I hopped on, backed it up and tried the hoe. It seemed ok. Salesman had called that day to let me know that when the mech took the valve apart, there was "something" stuck in the pressure relief valve. He flushed it out and pressure tested, was ok.

Soo....As the guy was pulling out of the driveway, it occured to me that a quick dig would make more sense, so I started it and took it over to a spot where I had dug a stump out. Extended the dipperstick and went to pull back....Almost no pressure at all. More than there was, but nothing like before the malfunction. Before, if I caught a root, the dipperstick would drag the whole machine, outriggers down and all, til I let off the lever. Now...Nada. So, I called the salesman, he called the flatbed driver, who turned around and came back, loaded it back up, and away she went...Another weekend with no Kubota....

They were supposed to call Saturday, didn't hear from them, so I'll be on it tomorrow. Salesman said something about them just replacing the whole valve this time.....

I'll update when I have a concrete answer, but would still welcome any input if anyone has suggestions or has had similar prob.

Mike

 

[leonz]

Thats just lovely,


it sounds like you have a bad relief valve to begin with as it is an open center hydraulic system; my other question to you is does the same thing occur with the front end loader if you have one installed?, if it does happen it narrows it down to the pump or the system relief if the backhoe does not have relief valves for each spool that return flow back to the tank.

EDIT: now that I read the first post "whoopsie" the spool is bad and or the relief valve should be changed.

 

[CHDinCT]

Maybe a simplistic suggestion, but the first thing I'd try is to disconnect and reconnect the QC's. I know with my loader, every once in a while, a quick connect will come unseated. It will look fine, but isn't fully seated. Maybe the dealer tried that already, or unhooked and rehooked in the process of troubleshooting it, but it might be worth checking with them.

 

[Bing187]

Thanks for the replies.

Talked to Norfolk today, they sound pretty confused. Apparently the pressure readinfg when they check the pressure in the lines is exactly what it should be, but they agree that it has zero power when put to the piston. In my mind, that means that either the piston is bad, and fluid is going past the packing and out the other line, or the relief valve is bad...... Salesman told me that the owner of the company and two other mechanics were working on it, one was back and forth on the phone with Kubota, trying to isolate what the problem might be.

I didn't check the QC's, but I would think that since they've had the valve apart, they would have checked. At any rate, it wasn't leaking a drop of fluid anywhere, and when they dropped it off, the dipperstick was working, if only a little. If the QC was loose or not seated, it would have popped the rest of the way off when I was using it. Thanks for the suggestion, tho.

Hoping that they straighten it out mighty quick, as I have a job to do with it on Wednesday that I'll have to pay to have done if it's not back. They've been cool about getting to it quicklly and trying to figure it out, but it's a bit of a bummer that this is EXACTLY why I bought a new machine, so that I wouldn't lose time fixing or waiting to have stuff fixed....Oh well. Not much else I can do about it at this point but wait.

Mike

 

[leonz]

One hopes they even bothered to connect a good double acting cylinder to the rear outlets and attempted to extend and retract the test cylinder before they dove into things and in the process eliminated the system relief valve of the tractor of which there are 2 if the tractor has 2 pump sections.

They would have system pressure at the remotes as a matter of normal operation when plugging in the gauge at the pressure side remote ports anyway.


Pressure testing and adjusting the system pressure with 180 degrees hydraulic oil temperature goes along with the proper flow rating of a hydraulic system, so they did nothing substantial.

If they are not using a flow rater to check the system pressure and flow under a load they are just spinning thier wheels in the snow.

 

[mkane09]

I had a very similar problem after replacing a hose on my grapple. Everything would be working fine and suddenly I'd have no pressure opening or closing the grapple and raising and lowering the FEL. Roll function was normal. I called Brady Barlow and he suggested disconnecting and re-connecting the QDs for the FEL and the grapple. That fixed it. I worked 4 hours yesterday with the grapple and had normal function of both the grapple and the FEL.

mkane09

 

[crazyal]

I'm not sure if you would be able to tell but I can feel when the pressure relief valve kicks in, kind of a feeling and sound. I think you need some seat time to feel it though. But if that was what's bad I would expect everythign hydraulic would have little to no power. I would think you wouldn't even be able to lift your wheels off the ground with your outriggers.

I think you're most likely correct and something internal to the cylinder went, bad seal, piston, or damage to the cylinder wall. I had the bolt that held on the piston to the rod unthread and then come off. At first it acted just like air in the cylinder. Once it came off I could extend the cylinder but when I moved the lever to retract it nothing happened. Luckily it didn't damage anything and gave me a chance to learn how to replace the seals.

 

[Bing187]

I have a good friend that is a mech for a fork lift dealer, he's a pretty smart guy. One of the things he checked the day that it happened was to bring the dipperstick all the way in, and hold the lever. There was no change in sound or engine speed, nothing. I know the sound and feeling that you're talking about, though I find it less pronounced on the Kubota than other hydraulics that I've operated. It FEELS like there's no pressure going to the cylinder, but it would feel that way if the cylinder is leaking fluid internally too.....

Mike