L-35 BH boom

[Alphonse]

Hello
I have a glitch with my L-35 backhoe boom, it has happened over a few years.
The boom won't come up.
The first time this happened the dealer sent a mech out and replaced the valve. No problem for a couple years. Next time it happened, they sent the same mech with a new valve. Worked fine.
The very next day it wouldn't come up. I'm frustrated and out several hundred bucks so I pulled the thing apart and replaced with the OLD valve.
Worked fine.

Sometimes the thing works after I shut off and do something else for awhile, sometimes not. That's when I have to wrench.

Any ideas on what the cause could be?

 

[RCW]

Alphonse - don't take this to heart, because I'm guessing some, and don't have experience with your problem.

I seem to remember a couple guys here on OTT having intermittent problems with backhoe operation, because there might be some junk making the valve stick and not work right.

Works, then doesn't. Kind of like replacing the old inoperable valve and having it work again.

If you do a search for backhoe valve, or something like that, maybe you'll find it.

Best of luck!

 

[Alphonse]

Thanks for the response.
Tractor sat on the job over the weekend, fired it up this morning and no problem for a half hour, then stuck again.
A friend said maybe some dirt in the valve but if that was the case, why does it never migrate to other valves? Only boom lift.

 

[lugbolt]

Check the safety valves.

 

[Alphonse]

Update.
Swapped valves again (old/new) and got nada.
Swapped up with down valve, away we go.
As Lugnut said, maybe sticky P/R?
I don't have a test bench, know a way to verify?