Bobcat Lift Cylinders

This is my little Bobcat 543B. Both of the hydraulic lift arm cylinders began to leak a little recently. Would it be best to take the Bobcat in and let a shop replace the seals in the cylinders? I never replaced seals before....

If they are like a 753, it's an easy fix. There is an aluminum head that screws on the end of the cylinder.

One came right off, the other seized and ruined the threads. Had to replace the aluminum part, but Bobcat had the parts. Take the old seals with you, it was a guessing game to figure out the seals.

Seals are not hard to replace, as long as you know from a diagram how the cyl comes apart- many different types. I wouldn"t take the whole machine to a shop- you can save some labor cost by taking the cyl off the machine yourself.

If you are going to own anything with hydraulic cylinders, no time like the present to learn how to repair them. Soon than later, they will leak.

This what I was thinking until I called Bobcat. They told me to bring the whole machine in, because it would be easier to replace the seals that way. I don't know, hard to tell where to begin just by looking at it. Price they quoted me over the phone was 3-4 hundred to replace them both, about 1 1/2 - 2 hours each cylinder.

(quoted from post at 13:23:48 01/23/16) This what I was thinking until I called Bobcat. They told me to bring the whole machine in, because it would be easier to replace the seals that way. I don't know, hard to tell where to begin just by looking at it. Price they quoted me over the phone was 3-4 hundred to replace them both, about 1 1/2 - 2 hours each cylinder.

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Are you close to a hydraulic parts/repair shop? I took an old cylinder in and they replaced the seals for no charge...just the $20 for parts while I waited.

(quoted from post at 12:42:16 01/23/16) This is my little Bobcat 543B. Both of the hydraulic lift arm cylinders began to leak a little recently. Would it be best to take the Bobcat in and let a shop replace the seals in the cylinders? I never replaced seals before....

Click to expand...

Do not remove the cylinders to rebuild them. You are making more work for yourself. Raise the loader and set your boom stop on one of the lift cylinders. Then disconnect the rod end of the other cylinder and unscrew the rod gland nut. You will have to buy or make a pin style spanner wrench to do this. After doing this remove the rod and replace the seals. When doing this I would loosen up the hydraulic lines by opening up the rear door to access the lines. By doing this you can pull out and push in on the cylinder rods as the oil has somewhere to go.

Between Bobcats, and other brands, I've done hundreds of cylinders. In fact I did both lift cylinders on a Bobcat about two months ago.

The best thing to do is what JimWV said. Either that, or find something to prop lay the bucket on to hold the boom up. From there, pull the rod end of the cylinder loose from the boom and let it drop down. Lay a block or something under it to keep it horizontal. Now fire up the machine and "lift" the boom. Given the fact there is no load on the loose cylinder, it will extend out by itself. If you let it bottom, and pressure starts to build, the other cylinder will try to lift the boom by itself, and potentially twist it, so be careful.

Once you have the cylinder extended, break the lines going to the cylinder loose to prevent it from building pressure/vacuum as the rod/cylinder is removed. From there, take the gland loose and remove it and the rod as an assembly. Depending on how tight the seal on the piston is, you may have to use something to pull it all out of the barrel. I had to do this on the last one I rebuilt.

Once it's out, clamp the eye end of the rod in a vice, remove the nut/bolt holding the piston to the rod. Now slide the gland off the end of the rod and remove the seals. Watch as you take them out as there is a right and wrong direction.

To get the rod seal back in takes a combination of finesse and force, but it's really not that hard once you figure out the tricks (ie-it needs to be folded into almost a U shape to get it into it's groove).

Once you've got the new seals on/in the gland, slide it back on the rod. A little Vasoline makes it a lot easier, and it's not as messy as using liquid oil. Next put the piston back on the rod, and tighten the fastener. I usually use a drop of two of red Loctite to insure it doesn't back itself loose.

I can't remember if the kid had new piston seals, but I believe it did. If it does, put them on the piston. Again, watch how the old one comes off.

Once everything is back together start the assembly back into the barrel. You may have to use a hammer to get the piston seals to compress enough to slide everything back in. If so, don't be afraid to give it a few hits. Just watch the piston seals and insure they compress and not try to jump out and wind up damaged. Not trying to scare you here, but just be careful and keep your eyes open. I've only had a couple jump out, so it's not likely, but it can happen.

From there, tighten the gland back up, tighten the lines, and run the boom up and down to get the air out of the system. Once you've done that, repeat the whole procedure on the other side.

Having to do it with one cylinder blocked makes things a bit more of a PITA, and uses a bit more oil than being able to prop things up and doing both cylinders one after another, without having to raise the boom to get the air out of the system so it will stay up for the other side. Either works, but a using something as a prop to hold it up would be my first choice if it was available.

Good luck, and post again of you've got any questions.

Thanks to you and everyone else that replied. I understand much more of what needs to be done....