Yanmar loader won't lift ???

[TnAndy]

OK.....I'm stumped. 2011 Yanmar with Yanmar loader that hasn't had a problem since new (other than the curl has slowly tilted forward for several years.....I can live with it), and worked fine yesterday. This morning I get on it, the loader will only lift about 12" and seems to hit a dead stop.

Curl function seems fine, near as I can tell with only 12" of lift. Engine lugs down a bit when I hold the joystick back at the 'top' of the current lift amount, so I assume fluid is flowing thru the joystick valve block and the pressure relief is working. Check for obvious physical obstruction or leaks reveals nothing....so I assume it's something internal.

But what ?

All help appreciated.

 

[RNeumann]

Check fluid level.

Remove the front (piston end) of the two lift cylinders off the loader and verify function of one or both lift cylinders. This shouldn’t be too hard it’s just one pin per cylinder.

 

[TnAndy]

OK...fluid is correct level. Both lift cylinders will extend about 4-5" from the full closed position when taken loose from the loader frame, then stop dead just like when they were attached to the loader.

Studying a bit, I'm thinking something has stuck in the SCV valve that the joy stick connects to. Joystick has two cables that run down to the SCV and pull/push either valve forward or back for the two operations of the loader.....one spool for the curl, one for the lift.

The curl will still lift the tractor off the ground, so it doesn't sound like a pump/pressure problem.....sounds more like that push/pull valve that runs the lift function simply isn't moving enough....something inside the valve block is physically stopping it.

 

[jaxs]

Could the cable have slipped? Try disconnecting cable and operating valve manually.

 

[RNeumann]

Can you crack/loosen one of the hydraulic lines that is on the front/piston side of the cylinder and try to extend it-retracting the cylinder will just suck a bunch of air into the cylinder so don’t do that. You will leak fluid but that should isolate the issue between the valve and plumbing to the valve vs the cylinder and “return/pb” plumbing.

I’d try that with the ram discounted from the loader.

It could be the valve but that’s an interesting symptom unless I’m not understanding it. It would seem a stuck or mis-adjusted valve and cables would go slow but it wouldn’t work for a certain distance and then stop.

 

[TnAndy]

Could the cable have slipped? Try disconnecting cable and operating valve manually.

Cable looks pretty solid on the connection. I can operate the joystick while standing on the ground on that side and see the ends operate the spools in the valve.....valve faces outward, so it's easy to see.

Since the lift goes up 12", then feel like is has hit a solid obstruction (engine loads some, indicating the pressure relief pressure has been met), my guess is disconnecting the lift cable end and manually pulling the spool isn't gonna do it, but I will try that to see.

 

[TnAndy]

It would seem a stuck or mis-adjusted valve and cables would go slow but it wouldn’t work for a certain distance and then stop.

My thinking as well.

I haven't seen the spool shaft, but I'd assume it's just a shaft with two notches in it.....in the neutral position, no fluid flow....pull it back, fluid flows in a notch to one end of the cylinder, push it forward, fluid flows to the other end of the double acting cylinder...ought to be pretty simple, and as you say it might run slower if you can't pull/push the shaft all the way so fluid flows in the notch as intended, but if you get ANY flow, it ought to move the cylinders fully...just slower....not a 'dead stop' after a few inches.

 

[TnAndy]

OK....dumbest thing. Reminder to check the simple stuff first.

Thought I'd switch the quick disconnect lines around to use the curl spool with the lift lines.....see if I could isolate whether it was the valve block, or something else. If the loader would lift with the lines switched, that would seem to indicate the loader end was fine.

Looking closer at the quick connects to try to see which went to which function, (Lines have color coded caps/rings to aid in getting the right hose to the right connector) I noticed one of the ones that is on a lift hose was sticking out farther than the other 3.....yeah, it wasn't connected....I'm guessing the return line, since the loader would lift a little. Pushed it on in solid, end of problem.

No clue how it came loose, been a long time since I took the loader off for anything, haven't had it off 3 times in the 7 years I've owned the tractor from new.

 

[RNeumann]

Nice! QCs have caused more than 1 problem......

 

[jaxs]

:thumbsup::drink: