loader arms lift *very* slowly

[jrheling]

Hi -

I've got a B3350SU with just over 1k hours on it and a 3rd function valve on the loader.

I was using the grapple yesterday to pick up some branches and suddenly the loader arms stopped moving up at their normal speed. They do move up, but at maybe 1/10th the normal speed. All of the other hyd functions seem fine: head tilt on the loader, grapple open/close, 3ph up/down. It's just the up on the arms.

I've checked hyd oil levels and they seem fine - dipstick near the 3ph shows oil at about exactly the halfway point between the two marks.

I found a number of threads (here and elsewhere) with similar symptoms that turned out to be loose or failed connections. I've checked all of the connections out on the loader arms and they're all snug, no signs of any leak. I also removed, inspected, and re-attached the quick connects under the acceleration pedal (where the hoses that route along the arms connect) that control the lower/raise function - they also seem fine.

In the course of doing this I stumbled into something that I think might be a huge clue for somebody who understands hydraulics better than I do (not saying much by itself ). While checking the quick-connects, I ended up draining the oil from yellow-tagged hose that connects to the pipe running along the arms (it feeds the arm raise/lower cylinders). When I re-connected everything and started the tractor up, it raised at it's normal speed, but just once and then it was back to being very very slow (maybe a little bit faster than yesterday but still way slower than it should be). I don't understand hydraulic troubleshooting well enough to work out what that points to, but like I say it certainly seems like a clue.

Appreciate any thoughts or suggestions on what to try next. I've rented a chipper for next weekend and I'm gonna have a rough time of it if I have to move all that brush around by hand

thanks,
Josh

 

[North Idaho Wolfman]

You have a bad or clogged disconnect!

The reason it moved fast right after you relieved pressure on a line is it now could move.
only to build and hold pressure again after use.

 

[TheOldHokie]

Hi -

I've got a B3350SU with just over 1k hours on it and a 3rd function valve on the loader.

I was using the grapple yesterday to pick up some branches and suddenly the loader arms stopped moving up at their normal speed. They do move up, but at maybe 1/10th the normal speed. All of the other hyd functions seem fine: head tilt on the loader, grapple open/close, 3ph up/down. It's just the up on the arms.

I've checked hyd oil levels and they seem fine - dipstick near the 3ph shows oil at about exactly the halfway point between the two marks.

I found a number of threads (here and elsewhere) with similar symptoms that turned out to be loose or failed connections. I've checked all of the connections out on the loader arms and they're all snug, no signs of any leak. I also removed, inspected, and re-attached the quick connects under the acceleration pedal (where the hoses that route along the arms connect) that control the lower/raise function - they also seem fine.

In the course of doing this I stumbled into something that I think might be a huge clue for somebody who understands hydraulics better than I do (not saying much by itself ). While checking the quick-connects, I ended up draining the oil from yellow-tagged hose that connects to the pipe running along the arms (it feeds the arm raise/lower cylinders). When I re-connected everything and started the tractor up, it raised at it's normal speed, but just once and then it was back to being very very slow (maybe a little bit faster than yesterday but still way slower than it should be). I don't understand hydraulic troubleshooting well enough to work out what that points to, but like I say it certainly seems like a clue.

Appreciate any thoughts or suggestions on what to try next. I've rented a chipper for next weekend and I'm gonna have a rough time of it if I have to move all that brush around by hand

thanks,
Josh

Symptoms point to a bad connection in the return oil path from the boom cylinders. The return flow is blocked locking the cylinders. Couple possibilities.

Fully lower the 3pt and test the loader. If it operates correctly with the 4pt lowered the 3pt feedback is out of adjustment

If the 3pt is not the problem check the quick couplers on the loader valve. To diagnose disconnect the yellow coupler and remove the coupler from the end of the hose. Put the open end of the hose in a bucket, start the tractor and raise the loader. If it operates normally and you get a stream of oil from the hose the coupler has probably failed in the closed position or its not fully connected.. Make sure the coupler is fully connected and if the problem persists replace both halves of the coupler.

Dan

 

[torch]

Another possibility is the internal layer of the return hose may have collapsed or torn, blocking flow in one direction.

 

[jrheling]

Thanks folks! @TheOldHokie I tried what you described.

First I confirmed that the problem persists even when the 3ph at the lowest position.

Then I disconnected the yellow coupler, removed coupler from hose, put the hose in a bucket (see photo - I think I'm doing what you described) and started it up to try again. After removing the coupler a small amount of oil came out (did not seem like a full hose's worth - much less).

With the yellow coupler disconnected, there's no upward lift on the arms now.

What does that point to? Could this point to a collapsed return hose, as @torch suggested?

 

[TheOldHokie]

Thanks folks! @TheOldHokie I tried what you described.

First I confirmed that the problem persists even when the 3ph at the lowest position.

Then I disconnected the yellow coupler, removed coupler from hose, put the hose in a bucket (see photo - I think I'm doing what you described) and started it up to try again. After removing the coupler a small amount of oil came out (did not seem like a full hose's worth - much less).

With the yellow coupler disconnected, there's no upward lift on the arms now.

What does that point to? Could this point to a collapsed return hose, as @torch suggested?

Looks like I got the wrong coupler. Yellow must be the UP side. Put that one back togeter and repeat the test using the other coupler/hose.

Dan

 

[jrheling]

OK so I think what I understand from your hypothesis, @TheOldHokie, is that the coupler on the return hose is maybe bad. Between what I saw happen when I disconnected yellow and my read of the relevant part of the manual, I think yellow is the head end side and white the return, which would make the lack of any lift when yellow is disconnected make sense.

So, following on that, I tried the same process you described but using white instead of yellow, and behold - the loader arms lift and I get a nice fat stream of oil out of the white hose in the bucket.

I'm off to try to get a new coupler pair.

 

[jrheling]

LOL - excellent! (Sorry - was writing my latest when yours came in)

Perfect! I can't tell you how grateful I am for this help, Dan. I'll report back after a new coupler pair is in place.

 

[TheOldHokie]

OK so I think what I understand from your hypothesis, @TheOldHokie, is that the coupler on the return hose is maybe bad. Between what I saw happen when I disconnected yellow and my read of the relevant part of the manual, I think yellow is the head end side and white the return, which would make the lack of any lift when yellow is disconnected make sense.

So, following on that, I tried the same process you described but using white instead of yellow, and behold - the loader arms lift and I get a nice fat stream of oil out of the white hose in the bucket.

I'm off to try to get a new coupler pair.

You are a quick study. That is exactly the thought process. Those couplers are probably not stabdard AG ("pioneer") couplers like sold by TSC and friends.

Dan

 

[jrheling]

My local Napa (which makes hyd hoses) doesn't have that coupler in stock. When I talked the owner through the problem and hypothesis, though, he was pretty skeptical that it was the coupler, and demonstrated by blowing through it that it was open when connected and closed when disconnected.

This seems to me like a persuasive test - do you agree @TheOldHokie ?

I think the conclusion from the hose-in-the-bucket test is that the problem isn't in any of the hoses or connections on the arm. (Right?) And then if it's also not the connector, that points to problems upstream - i.e. the control valve or similar? What can I check here?

 

[TheOldHokie]

My local Napa (which makes hyd hoses) doesn't have that coupler in stock. When I talked the owner through the problem and hypothesis, though, he was pretty skeptical that it was the coupler, and demonstrated by blowing through it that it was open when connected and closed when disconnected.

This seems to me like a persuasive test - do you agree @TheOldHokie ?

I think the conclusion from the hose-in-the-bucket test is that the problem isn't in any of the hoses or connections on the arm. (Right?) And then if it's also not the connector, that points to problems upstream - i.e. the control valve or similar? What can I check here?

The test demonstratef the problem is an obstruction in the return side. Coupler is an obvious sudpect but there are other posdibilties. Put the fully assembled coupler back on the hose but do not connect it to the pipe. Run the test agsin with the fully assembled coupler in the bucket. If the loader works with the coupler connected the problem is not the coupler. Put the coipler back on the pope and test again. If the loader still does not work the problem is somewhere downstream pf the coupler. We slready ruled out the 3pt whicj makes things interesting....

Dan

 

[jrheling]

Ah, yes, that makes sense - this should either 100% point to the coupler or 100% rule it out. Will go do that right now.

 

[jrheling]

Bingo. Fully assembled coupler in the bucket emits _some_ oil, but just a bit, and nowhere near as much as when the coupler wasn't on. (Also the loading is still slow)

Seems like a smoking gun, so I'm gonna try to get to my local Kubota dealer before they close.

Thanks again, Dan - you're really saving my bacon!

 

[TheOldHokie]

Bingo. Fully assembled coupler in the bucket emits _some_ oil, but just a bit, and nowhere near as much as when the coupler wasn't on. (Also the loading is still slow)

Seems like a smoking gun, so I'm gonna try to get to my local Kubota dealer before they close.

Thanks again, Dan - you're really saving my bacon!

If returning to NAPA educate your NAPA representative on the difference in flow characteristics between blowing air and a 2+ GPM of hydraulic fluid