Front end loader cylinders bleeding off

   / Front end loader cylinders bleeding off #1  

manwith2jd

Member
Joined
Aug 18, 2008
Messages
37
Location
SE Missouri
Tractor
JD4300, 4wd, SRT, 2005 X740, 318, 2007 X740, Turf Gator 4x2
JD 4300 with a 460 loader, loader lift cylinders bleed off, especially at low rpm, not as noticeable with rpm at mid range or above. If I swap the lift cylinder and bucket cylinder hoses at the manifold will that tell me anything? My thought is that after swap if problem goes away it's in the SVC valve and if not it's in the lift cylinders themselves. Any ideas on how to troubleshoot and identify what to work on? Loader has low hours on it, maybe 50 hrs. use! Loader has a 6' HD bucket attached. Any help would be appreciated!
 
   / Front end loader cylinders bleeding off #2  
Welcome to TBN:D

This question would be better posed in the hydraulic forum...But:

Are you sure it's a 460 loader? Only the 420 and 430 loaders where available for the 4300...

Swapping the hoses is one way to troubleshoot, but more that likely the cylinders are the problem. There where a few design changes in the seals, and if you have an early serial number than you probably have the older seals. New seal kits are about $25 per cylinder, and I would suggest rebuilding all 4 at the same time. If this is something you want to tackle yourself, there are a few good post's on here that show the process pretty well.
 
   / Front end loader cylinders bleeding off #3  
On a da cyl, you can remove the drop hose, and then pressureize the lift hose, and see if any oil shoots out the drop port on the cyls.. if so.. packing is bypassing..

soundguy
 
   / Front end loader cylinders bleeding off #4  
You might try this to positively check out your cylinders. A hydraulic hand pump will pump up to 10.000 psi. You don't need to pump it up that high, but it is there if you want it. You will need to add a 10,000 psi gage to the line going to the cylinders. Hook up at one of the ports and pump up to the cylinder pressure, usually around 2500 to 3000 psi. If hydraulic fluid comes out of the other port or opening on cylinder, it is bypassing, fluid slipping past the o-rings or seals. Then try the other port and do the same thing. This will give you a feel of your cylinders ability to operate as advertised.

As far as the valve, you could probably test that to. but understand this. O-rings go bad or not perform as they should, and certain valves have certain tolerances, and some valves leak more than others. In military mil-spec items, each item is tested/inspected for specifications. In civilian world, maybe 1 out of a 100 might be inspected. As someone mentioned, there are pilot operated load checks, if you have them, and your cylinders are good, you will have more faith in your system. I see people working close to and under loaded buckets quite often.

I have often seen buckets left in the air, dump trucks in the lift position, and wondered why. Maybe someone here has an answer. This is a dangerous condition, if you have kids around. Maybe it is to keep the seals tight. Don't know.
 
   / Front end loader cylinders bleeding off
  • Thread Starter
#5  
It's a 430 loader, numbers of this stuff sometimes confuse me! I did rebuild the bucket cylinders a couple years ago, not confident that I did the job totally correct (winged it), but they work and seem to be holding up. Thanks for the info and will research the correct procedure for rebuilding these lift cylinders. Will try and find info you said is on this site on rebuild procedure. And yes I'm a newbie!
 

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