Loader Kubota LA463 Loader Help

   / Kubota LA463 Loader Help #41  
A tip on bleeding cylinders.
Some applications like the bucket curl have mechanical stops, this can prevent the air from getting out as easily from cycling.
I usually hook up the lines and loader frame side of the cylinders then cycle them fully a couple times before connecting the bucket side of the cylinders.
 
   / Kubota LA463 Loader Help #42  
Your wish is my command.:dance1:

In the end, I rebuilt both bucket cylinders on my LA463 FEL. I needed to see the seal arrangement on the good cylinder in order to do the leaking one, which was dismantled when I got it back from the hydraulic shop. I am taking them to small claims court over this, but that is another story.

There are two main parts that have seals, wipers, spacers and/or expanders. The piston on the shaft and the cylinder head which the shaft slides through and which screws into the end of the cylinder housing. This cylinder head has an internal wiper and seal. The wiper, which provides dust and dirt protection, is relatively easy to pop out and replace. But the inner seal is a bear. Hard to remove and harder to get the new one back in. Eventually, I found that lubing it with hydraulic fluid and using 1/2" wood dowels from each end, I could dis-form it sufficiently to finally snap into its groove. For a while, I was not sure I could get it in, but it can be done with persistence.

The bigger issue was the primary seal on the piston. It is a hard plastic material and very inflexible. You need special tools according to the service manual, one to get it on the piston, and another to compress it so you can slide the piston into the cylinder. Messick's service department advised using hot water or hydraulic fluid to soften the seal, but that did not work for me. I finally used a heat gun, warmed the seal to the point I could just barely handle it without gloves, and stretched it by hand until I was able to force it over the piston. The expander, the wider looking seal on the right is slit and is no problem to get on.

View attachment 648801

Now you have to get it into the cylinder, but the seal is now oversized and sloppy on the piston. The solution, while it is still warm, tighten a hose clamp around the seal and let it cool. Then reassemble the cylinder, the piston will slide right on in. It will re-expand to its original size with a little time once inside.

And the last bit of information I have is to share: The panic I felt when once it was all back together, all new hydraulic fluid and filters installed, and my first operation of the bucket. The bucket would rotate up, but not hold position. It would sink back down over 10 or so seconds. Over and over I tried, but the bucket kept falling back. I finally went out to a pile of dirt and decided to put a load in the bucket to generate some hydraulic heat. I was sure those two plastic seals were not yet seating. Two dozen times I rotated that bucket and two dozen times is fell back down. And then, suddenly it stopped dead in its tracks while falling. I exercised it several more times and viola. No hits, no runs, no balls, no leaks, no smoke, no funny noises, no joke, no nothing. It was now rock solid. So what happened?

I am pretty sure the cylinders had not filled completely and needed all that exercise to purge all the trapped air. I just had not been smart enough to figure that out until after the fact. :mur:
Where did you get o rings and seals?Do you know part number?
 

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