Some notes and observations from my recent rebuild. Yes you can rebuild the boom cylinders in place but there are some tricks. I left the cylinder end bolted up and removed the rod end. One issue is that the play in the rod end where it fits over the pin on the boom is quite tight and trying to slide the rod end off the pin is not possible as the rod end gets at an angle to the pin. The trick is the pin goes all the way through the boom and should "float" . I didnt realize that initially and used a big gear puller to push the pin out of the rod. The pin through the boom eventually moved and the pin came out of the rod end.
Getting the rod and piston out of the cylinder required a power pull tied to the bucket. Even with all the hoses disconnected there is a lot of friction on multiple seals and wipers. The cylinder and rod need to be held up in place when they come apart. It may not be an issue with well worn set of seals but with low hours on mine, they were tight.
I then moved to my shop to work on the seals. The threaded plug at the end of the cylinder needs to slide down the rod so it can be removed. The only thing holding it is a lip seal and wiper but it comes off hard. I used two long Jorgenson pipe clamps and the plug came hard despite trying different lubricants. It does not come off smooth, crank on the clamps and it wll jump forward 1/8 of an inch. One way to reduce this effort would be to extend the rod with the hydraulics after its clear of the pin on the boom but that means waiting on unscrewing the plug. IMO, its just another chance to spray hydraulic fluid everywhere.
Getting the big piston bolt (1" grade 8 ) loose requires a lot of torque. I have long 3/4" drive breaker bar and it took all my weight to break it loose. Its a 1-1/8" socket. I doubt a 1/2" drive would work. My 1/2" drive electric impact would not touch it.
Once the piston is off, the plug can be slid off the end of the rod. There are a couple of split guide rings, a wiper seal and the lip seal that have to be inserted in the bore. Getting the lip seal in can be done without a special tool but there is one that shrinks its OD by distorting the ring. As I found out, the lip seal needs to face in towards the piston. In my case the original lip seal was reversed to point out towards the teflon wiper seal causing the leak.
Getting the teflon seal on the piston is not easy. Teflon is not that "stretchy" Foxkits has a video using a small tie wrap to coax it on. Once the ring is in place it will need to be compressed back into the groove. I used a method I saw on YouTube, wrap the outer diameter of the teflon with electrical tape and use a screw type hose clamp to clamp it down for several minutes. It worked quite well.
Next thing is to slide the plug back on the rod. Like getting it off, it really does not want to slide. I had some long 3/8" all thread in stock and made up a special plate with hole in it sized so that the plugs smaller diameter end slips in the hole. The two threaded rods then sit parallel to the rod on either side and run to the rod end where there is another cross piece across the end of the rod. By cranking up the nuts on the all thread it slowly slid on a bit at a time. I just needed it to slide on a foot or so.
I cleaned up the big bolt and the threaded hole as well as I could as used electrical contact cleaner to get the threads clean and dry. I used Loctite blue on the threads and used my breaker bar to crank it tight. The tables show 625 ft/lbs of torque for a 1" grade 8. My 3/4" torque wrench does not go up that high so I just applied all my weight on a long breaker bar.
I then slide the rod and piston in and the seals seemed to clear. It took a bit of persuasion to get in in far enough to engage the threads of the plug but eventually I got the plug screwed in.
The last thing to do is get the rod end lined up with pin in the boom. Sounds simple but it was not easy. I started up the SEE and moved the boom lever to move the piston but its not smooth as its not full of oil immediately. Even with the rod end lined up with a cleaned up pin, it did not want to go in. I had to make up another clamp with all thread to push the pin from the other side of the boom into the rod end. Once the set up was in place it went quick.
BTW the snap ring on the pin is very beefy and regular snap ring pliers would have a tough time on them. I got a screw type ring remover on Amazon to get the ring on and off.
The boom cylinder definitely does not move smooth initially but once the boom is slowly exercised it smooths out. I could not stroke it fully as I didnt have a hole to dip into but expect it will need a bit of exercise through its entire range.
So two special tools to buy, the special wrench to unscrew the plug and a two foot 3/4" breaker bar to turn it and the heavy duty snap ring tool. A 3/4" drive breaker bar a minimum of 3 feet long and a 3/4" 1-1/8 socket. I did this solo, if I had unbolted the cylinder and hauled it to a shop to get it rebuilt I would have needed an assistant or a overhead lifting tool.
