Case 310 loader backhoe - need some advice

[robilmichael]

Hi, I have a Case 310 loader backhoe with the dual range, shuttle shift, ps, etc. The unit runs very well with no smoke or blow by, all hydraulics work well and it has plenty of power. I had a few of the hydraulic cylinders professionally rebuilt since they were orginal and were weeping, including the boom cylinder. The boom leaked down about 4 inches every 10 minutes or so and even after a professional rebuild it still leaks down. This tells me that there is a leak in the control value or some pressure control valve. There is no boom lock on the unit either so I really need to fiqure out how to fix this. I have the service manual and the owner's manual and they do not address this problem.

Attached are a few pics of the unit and close ups of the control valve. Can anyone tell me how to diagonse this problem and how to fix it?

Any help would be appreciated.

Thanks.

 

[robilmichael]

Here are the pics.

Any suggestions?

Thanks.

 

[TimBinWV]

Good looking machine. I"m not a hydraulics expert, by any means, but I"d have to think it"s an O-ring or something in the boom valve that"s causing it to leak off. Do any of the other functions leak down? If you put down pressure on it will it also leak off?

 

[BarryfromIA]

One thing that could have happened during it's working life is that an operator could have lifted the boom at full throttle and bottomed out the cylinder and stretched tube in the cylinder. There is a lot of oil flowing at full throttle and it has to go some where. It happens to out rigger cylinders also.

 

[robilmichael]

Thanks. Here is another pic. No other components leak down, so it is unique to the boom. I will try to put pressure on it and see if that leaks down. I will try to take apart the pressure relief valve and see if there are any o rings in there and replace them as well.

I will also fabricate some type of boom lock.

I like the machine as it works well (not nearly as fast or as strong as a 580 though!) and was cheap to buy and operate.

I also plan on sanding down the surface rust and repainting the entire thing Case yellow this fall.

 

[TimBinWV]

Something else you may try is plumbing the boom to another location on the valve, if possible. This would eliminate the valve being the culprit, if the boom still leaks down.

 

[oldproudvet]

I fabbed a "link" between the boom and chassis, utilizing the factory bracketry that locks the boom to the extreme right. You obviously can't move the unit down the road or thru the woods with boom and dipper hanging so far to the side. It works for me. You're right it's a little hoe, but it sure works well on my farm, ditch cleaning, field road culvert setting misc stump work etc

 

[robilmichael]

Thanks. I will post some pics once I build the boom lock. I will come up with something that locks it up and straight back.