Backhoe function issue

[CK20Doug]

I have a KB 2365 backhoe that I have had for 15 plus years with several hundred hours use. A while back the dip function would intermittently seem to lock or travel very slowly only on the return stroke. At first it was only now and again then became constant. I have replaced the cylinder seals and disassembled the spool valve and associated load control valves for inspection and cleaning with no signs of damage or heavy wear. I noticed after reassembly that the problem seems to go away if the engine is at idle or slightly above but rev up to operating RPM and it appears to lock up after an inch or two of travel on the return stroke, (which is extending the ram) All the other functions on the backhoe work flawlessly. I was wondering if anyone else has run up against this issue. I am thinking maybe a bad or weak spring in the load hold check valve or maybe the anti Cav. valve

 

[BukitCase]

If you have the original hoses it might also be that one has de-laminated internally, which can cause a "check valve" effect - if so, it will usually be a "one way" check valve, and will get worse with increased flow... Steve

 

[CK20Doug]

If you have the original hoses it might also be that one has de-laminated internally, which can cause a "check valve" effect - if so, it will usually be a "one way" check valve, and will get worse with increased flow... Steve

Thanks, I am going to try trading out the check valve from different function on the control block first ,then hose

 

[BukitCase]

Good plan; sounds like you're aware of the pitfalls of "shotgunning" - (for those not familiar with the term, it refers to the practice of changing SEVERAL things at once, then wondering which one fixed it ) ... Steve

 

[mxr662]

Good plan; sounds like you're aware of the pitfalls of "shotgunning" - (for those not familiar with the term, it refers to the practice of changing SEVERAL things at once, then wondering which one fixed it ) ... Steve

We referred to that as "swap till you drop"

 

[rScotty]

When I run into a hydraulic problem the first thing I do is put a temporay hydraulic test gauge in the circuit and mount it so I can see the gauge from the cab. Then when the cylinder quits moving I can see if the pressure at the gauge goes high or low.
Then with a hydraulic schematic and moving the gauge to diffferent places it's possible to pin the problem down.
Someday I hope to have a hyraulic gauge with an adjustable flowmeter like a real hydraulic mechanic uses.
rScotty

 

[CK20Doug]

Problem resolved, hydraulic line internal lining failure. Thanks for all the info