Loader can only lift its own weight

[427cjackson]

Although this is my first post, I've been reading up on my L3830HST here since I've owned it. I really just started using my tractor last year. Bought it second hand and it now has 1610 hours on it.

I'm now stuck with a problem that I can't find any information on. With no weight in the bucket (LA723), the loader will cycle all the way up as well as lift/curl. When I put weight in it (~700 lbs), the loader will raise to about 5' at normal speed, but will slow to a crawl for another 6" and then stop completely (about 2'-3' short of its full height). I don't remember doing anything out of the ordinary with lifting recently, but have moved some heaving objects this summer.

I read some posts on cleaning the pump screen, but can't seem to find where that is located. Does anyone know? When I described this to the dealer, they said probably bent lift cylinder. I don't see any fluid leaking and would assume I would see if the cylinder was bent. Is there a way to check?

I did replace the trans/hydraulic fluid with SUDT2 and filters at 1600 hours, but only noticed this issue last week.

Chris

 

[Tooljunkie]

Couple things, one is fluid level, sorry i dont know where screen is.
Three point centered or not under load.
Accessory circuits neutral or off.

Welcome to the site,theres a wealth of information here.

 

[427cjackson]

I should have mentioned, fluid level is just above the minimum line (same as it was before I did the service).

There are two rear remotes, but there is nothing connected. The control springs back to center after they are engaged, so I believe that means they are in neutral. I'm not sure what you mean by "off", or if that is possible.

The frame-mounted backhoe is on, so the three point hitch is not on the machine. I have always carried the three-point in the up position, but read something on this site about carrying it lowered. I did lower it and cycled it a couple times (I had to push it down by hand because there was no weight on it).

 

[Stubbyie]

You mention a frame-mount backhoe being mounted.

It sounds like a problem of hydraulic flow.

Does your machine have a valve perhaps with a pull lever handle that redirects hydraulic fluid flow when the backhoe hydraulic circuit is in use? I think that's what is meant by another poster's "off" comment.

Check closely our Owner's Manual and / or Parts Schematic for such a critter. Mine is on (facing forward) right side with the pull lever pointing backward. Look close as mine is just a finger loop right behind the BH operator's (now facing backward) left knee. Should push-pull in-out. Again, check the Manual for which orientation is correct.

Also get your hydraulic fluid up to 'full' level. May be time to change fluid if you're not certain what's in there. Don't use a Universal hydraulic fluid, stay with Kubota SUDT or better. If changing fluid also change filters and double-check screen if present.

Please post back your continuing experiences so we may all learn.

 

[427cjackson]

My backhoe hydraulic is part of the loop...there isn't a shutoff to bypass it...the fluid is continuously (I believe) flowing to the backhoe as it is always active...there's isn't a shutoff that I could see on the machine or in the manual.

I added a bit of fluid, but it only took a quart...still no change. I then swapped the hydraulic quick-connects from the curl/dump spool with the lift/lower spool and there was no change in the issue raising the loader under load. It seems like this would eliminate the loader control valve.

I'm thinking that the only remaining possibilities are the lift pistons or the hydraulic pump. Is there any way to test these? I believe I read somewhere about propping the bucket up and then disconnecting the hydraulics to see if the pistons hold (not standing underneath of course). How would I check pump effectiveness? Is there a way to plumb a gauge inline?

 

[Bluegill]

Does the backhoe work as it should? If so this would eliminate the pump.

Suction tube down by your right foot might be the culprit.

 

[Billdog350]

You have a lot of troubleshooting to do before looking at the pump, or anything else for that matter.

If your backhoe has full hydraulic pressure and movement at normal throttle, then you have eliminated a restriction, pump, or pressure relief problem. If it doesn't, then you get continue your search. Try to lift the machine up with the outriggers, can you do that? Try to lift the machine up with the backhoe...can you do that? When you're running the backhoe and doing two things at once, does it have enough pressure and volume to move smoothly and with power?

Honestly, your issue sounds more like a failed loader valve pressure detent spring...your pressure detent is kicking in way too early. Those can be shimmed up, or in your case I wonder if part of the spring broke entirely....

But do your tests with the backhoe first and then get back to us...

 

[427cjackson]

I did check the outriggers (raising/lowering both simultaneously) last night and was able to lift the machine. I'll try your other suggestions tonight and post back details. I have noticed before that the backhoe operation was odd, but this is my first tractor, I did not own it when new and haven't done a lot of work with the backhoe. I'm assuming when you say I can do two things at once you mean one operation with the right control and one with the left?

I didn't mention it before, but at some point last Fall I must have run over something that pushed a linkage under the machine (left side) into a hydraulic line (restricting it to about 2/3 of what it should be - but not breaking the line to cause a leak). I'm not sure how long it went like that, but I did replace it as soon as I did.

 

[Tooljunkie]

May be a long shot, but im thinking one of your lift cylinders is damaged. The bore could be scored where it runs out of travel.

It only takes a scratch to make a hydraulic cylinder perform poorly.
I overhauled all the cylinders on the loader, and replaced all the hoses, must have been something caught in a fitting, as it scored the bore. It leaked down fast. I honed it and replaced packings again, but it isnt perfect. If you open system up, i cant say how important it is to keep clean.

 

[427cjackson]

I was able to lift the machine with the backhoe at engine idle - no problem. Can you tell me where the loader pressure detent is and how I would go about checking it? I've read something about an adjustment at a "hydraulic distribution block" that controls flow between the loader and 3-point?

I was able to determine that my machine does not have the "pick-up tube screen"...it has two spin-on filters

 

[coachgeo]

air in the system?

 

[427cjackson]

I removed the backhoe yesterday to see if that was possibly the source...still have the same problem. I found the relief valve under the seat - removed and cleaned it - still have the same problem. I've read there is a similar relief in the loader control valve and will look for that today.

 

[kubotasam]

In your first post you said "dealer said it might be a bent lift cylinder" Have you checked? A very small bend can cause problems. Extend cylinder all the way out then lay a straight edge along cylinder rod. It needs to be perfectly straight.

 

[Billdog350]

427cjackson, the good news is that your hydraulic system (at first glance) appears to be fine. If you're able to lift the machine up, especially at idle, you likely have a perfectly good hydraulic pump, good flow through your filters, and a good pressure relief at your pump/machine.

Now for looking further, its easiest to borrow or buy a hydraulic pressure gauge and tap it in at your loader valve after the valve (one of the quick disconnects to the loader cylinders) and see if you're close to the recommended pressure. If you're way low...then your issue is very likely your pressure detent. If its right at factory spec, then you can start looking at damaged cylinders and such.

I have seen cylinders that were bent as well as cracked and damaged in other ways and they still worked decently, definitely better than what you describe. I'm not saying the cylinders can't be damaged or causing your issue, but I'd recommend checking out pressure at your dist block next.

 

[rentthis]

The first thing I check is inside the cylinder. It's easy to do and usually the problem. I have found a couple where the nut holding the piston to the rod had come off. Hard to believe but it happened. If that's the case, you won't likely see the cylinder leaking. More often, it just needs to have a piston seal replaced.

 

[427cjackson]

It took me some time to get back to this, but I've assembled a gauge to measure the pressure at the loader control valve. The pressure hits 2300 psi and stays there when I operate the valve. I'm not sure what the pressure should be, but I believe I read somewhere else on this site that this was about the right pressure. I also purchased a straight-edge and checked the cylinder on four side and it all appears straight. Should I attempt to look at the cylinder seals now? Is there a good reference her for how to disassemble and repair them?