HELP! My Backhoe won't swing left!

[Smokeydog]

Great! Have intermittent problem on left swing and boom down on the M59. So far been a temporary inconvenience but could cause a real problem. Suspected a similar cause but wasn’t sure I had the skill to attempt repair. Any pictures or additional documentation would help. Have good hydraulic shop to take parts to for them to help. Wonder if higher durometer or Viton o-ring would be better? Wonder why it tends to effect the left swing?

Repairs with the backhoe on or off the tractor?

Thanks for exploring the unknown and sharing.

 

[rScotty]

Great! Have intermittent problem on left swing and boom down on the M59. So far been a temporary inconvenience but could cause a real problem. Suspected a similar cause but wasn’t sure I had the skill to attempt repair. Any pictures or additional documentation would help. Have good hydraulic shop to take parts to for them to help. Wonder if higher durometer or Viton o-ring would be better? Wonder why it tends to effect the left swing?

Repairs with the backhoe on or off the tractor?

Thanks for exploring the unknown and sharing.

If the problem is in an overload relief valve (OLRV), they always come in pairs, so there are two of those relief valves on each control valve in the control valve stack that has them. One OLRV sits on top of the control valve and the other one underneath facing down.

Overload relief valves respond to outside pressure on the system, not hydraulic pump pressure like the regular relief valves do.

The shop manual illustrations are very good at showing fluid flow as each control is activated. After a little study, you can see that the relief vaves for "swing left" and "boom down" are both sitting on top of their control valve rather than underneath. I wonder if that would explain the handedness?

The parts book doesn't show parts for the OLRV, but the shop manual shows them in great detail. There is quite a bit more to say about those relief valves - but I'll wait until we find out if that is the part that "Ished" fitted with new O rings....or if it was some other control valve part.

BTW, the L45 and M59 backhoe control valves and reliefs look the same or similar. The parts book for the M62 hoe shows its control valve as is very different and more rebuildable.
rScotty

 

[Seven Gables]

Great! Have intermittent problem on left swing and boom down on the M59. So far been a temporary inconvenience but could cause a real problem. Suspected a similar cause but wasn’t sure I had the skill to attempt repair. Any pictures or additional documentation would help. Have good hydraulic shop to take parts to for them to help. Wonder if higher durometer or Viton o-ring would be better? Wonder why it tends to effect the left swing?

Repairs with the backhoe on or off the tractor?

Thanks for exploring the unknown and sharing.

I think these intermittent issues either no swing or no down pressure are very likely the port relief/overload relief valve stuck open. These reliefs are not simple direct acting reliefs. They are pilot operated which are a more precision design with more small moving parts , orings, springs and small orifices prone to issues.
Nice thing is there just a cartridge type that just thread into the directional control valve, easy to remove for inspection and repair. If it was me I’d pull the one out that’s on the pressure port for left swing , disassemble and inspect for any contamination, plugged orifice , broken or bent springs, worn orings and a good cleaning. Don’t forget to mark the position of the set screw before disassembly.

 

[Seven Gables]

Here’s some good info from the pages of my Volvo excavator service manual, they look to be almost identical to R Scotty’s illustration