Repacking/rebuilding a cylinder

[chanceu]

I got the wrench and it worked like a charm. I would guess it took somewhere between 100-150 lbs to get them loose. I didn't use a cheater and I didn't put all my weight on it.

I have the cylinders apart and I'll probably put them back together tomorrow or Saturday. I have attached some pics of the broken seals. It's easy to see what the problem was. I think the small frayed seal in cylinder 2 was what was causing the initial slow leak down and the split larger seals in both cylinders are what happened this past weekend when the bucket would stay up at all.

One question I have is when I removed the caps, it looked like there was either some pipe thread sealer or some sort of Loctite on the threads. I don't have a picture of the cap threads, but the white stuff on the seals in one of the pictures is what I'm talking about. Does anyone know what this is? Do I need to put thread sealer or Loctite on the cap threads when I put it back together?

 

[gclark94560]

I need a 2 1/8" wrench. I've only looked a couple places, but all the open ended 2 1/8" wrenches I've found were around $150.

Try Harbor Freight Tools - from their web site -

* Wrench material: hardened steel
* Pieces: 4
* Size:
SIZE LENGTH WEIGHT
2-1/8'' 24-1/2'' 6 lbs.
2-1/4'' 25'' 6-3/4 lbs.
2-3/8'' 25-1/2'' 8-1/2lbs.
2-1/2'' 26-1/2'' 9-1/2lbs.
* Shipping weight: 35 lbs.



ITEM 1965-0VGA

$62.99

 

[kennyd]

One question I have is when I removed the caps, it looked like there was either some pipe thread sealer or some sort of Loctite on the threads. I don't have a picture of the cap threads, but the white stuff on the seals in one of the pictures is what I'm talking about. Does anyone know what this is? Do I need to put thread sealer or Loctite on the cap threads when I put it back together?

It is probably thread sealant, like THIS, I think I would put some on the threads when I reassembled the cylinders.

 

[KJM]

The last(!) thing - you should be able to pull the rod/piston from the cylinder by hand (slowly). If you can't - be careful when you reach for a compressed air gun to "assist". Don't ask about that


Kevin, I cannot help but ask how far across the shop the rod and piston shot when you gave it a bit of assist air. I really laughed when I read that. Think potato gun with hydraulic cylinder.

I got to thinking of the 50 ton Grove hydraulic cranes that we had to replace the extension boom cylinder seals in. I forget now what the diameter of the largest piston(a telscoping hydraulic cylindar and rod) was (I am thinking 6-8 inches.) We had one stick and then come out rather, huh, forcefully. No real damage to the shop wall though.

We had to rig a dingle berry brush on a long rod with wooden carrier bearings to hone the thing. We had to replace the packing because they could not take the -50 and colder temps in Prudoe Bay without leaking and that is a no-no in precise work like bridge building when you have men working around the load.

Mike

Well, the full scoop on what happened wasn't that exciting. The cylinders on the backhoe are just under 3" in diameter, and I was aware that 80psi (which is what the reg was set to) would produce a rocket if not done carefully. I was careful - the blower/duster gun on the airhose was a "nice" fit in the JIC fitting on the cylinder. Nice, controlled extension. Beautiful to behold. Top of piston visible, keep going, nice, gentle. Got to the end of the liner in the cylinder and stopped. Naturally, I took the gun out of the fitting OILBATH!

Hydraulic oil ain't fun stuff to have pressure sprayed on your face. Not a mistake I'll repeat. Not ever. Caused some amusement for the rest of the family, BUT NOT NICE!!

/Kevin

 

[KJM]

I got the wrench and it worked like a charm. I would guess it took somewhere between 100-150 lbs to get them loose. I didn't use a cheater and I didn't put all my weight on it.

I have the cylinders apart and I'll probably put them back together tomorrow or Saturday. I have attached some pics of the broken seals. It's easy to see what the problem was. I think the small frayed seal in cylinder 2 was what was causing the initial slow leak down and the split larger seals in both cylinders are what happened this past weekend when the bucket would stay up at all.

One question I have is when I removed the caps, it looked like there was either some pipe thread sealer or some sort of Loctite on the threads. I don't have a picture of the cap threads, but the white stuff on the seals in one of the pictures is what I'm talking about. Does anyone know what this is? Do I need to put thread sealer or Loctite on the cap threads when I put it back together?

Glad you got it done. Looking at the pics, the seal scuffing is pretty extreme - have you checked for nicks and bumps in the cylinder? The chrome is also spalling and kind-of looks consistent with hitting the cylinder walls. The other possible cause of the destruction could be re-assembly - if there is a sharp ridge at the top of the cylinder. My bigger cylinders had a "liner" which had a very sharp top edge (sharp enough to shave a finger nail). I relieved the lip with a bit of wet-n-dry (and flushed it clear, upside down, with WD-40 after).

One last thing - you can clamp the nut in a vice and put a bar through the clevis end of the rod to unscrew. I found that easier, but my nuts had been welded on and needed some grinding first

I didn't use any sealant on the threads - the O-ring in the cap does the sealing. Sealer wouldn't hurt, but threadlocker will make you need a bigger bar next time

Cheers
/Kevin

 

[tommu56]

chanceu
I noticed some rust on top side of piston check the bore of your cyl for damage for any pits in there. Pits will chew up piston seal (which is what you show in picture) maybe some water got in to cyl from bad rod seal (the one in the cap) and caused damage there?

usually there is an o-ring on cap before threads to seal the cap to cylinder I usually put a LITTLE nevercease on threads.

tommu56

 

[chanceu]

I'm pretty sure the scuff marks on the flat rings happened when I pulled them past the threads in the cylinders. I didn't take any precautions to not damage the seals because I am replacing them all. I did peek in the cylinders and didn't see any damage, but I am going to look closer before I put them back together.

I noticed the rust and wondered how something rusted in a bath of oil especially since I haven't operated it in the rain and it is stored inside. My guess is it's from the dealer as I'm sure it sat outiside for weeks if not months before I purchased it.

As I said, I'm going to take a closer look in the cylinders before I put everything back together. I'm also going to hit the rust with a scuff pad just to make sure it isn't causing any damage. I really don't think there is any problems in the cylinders because I know I was doing something I shouldn't have been doing when the initial slow leak down started and I was doing something else I shouldn't have been doing this past weekend when the seals gave way for good.

The first time, I hit a rock going forward with the bucket curled down. There wasn't supposed to be any rocks that big, but lesson learned. This past weekend, I was back dragging with bucket curled down. I know it was wrong, but I also knew I was replacing the seals so I wasn't concerned if I broke an already broken seal.

 

[gemini5362]

I'm pretty sure the scuff marks on the flat rings happened when I pulled them past the threads in the cylinders. I didn't take any precautions to not damage the seals because I am replacing them all. I did peek in the cylinders and didn't see any damage, but I am going to look closer before I put them back together.

I noticed the rust and wondered how something rusted in a bath of oil especially since I haven't operated it in the rain and it is stored inside. My guess is it's from the dealer as I'm sure it sat outiside for weeks if not months before I purchased it.

As I said, I'm going to take a closer look in the cylinders before I put everything back together. I'm also going to hit the rust with a scuff pad just to make sure it isn't causing any damage. I really don't think there is any problems in the cylinders because I know I was doing something I shouldn't have been doing when the initial slow leak down started and I was doing something else I shouldn't have been doing this past weekend when the seals gave way for good.

The first time, I hit a rock going forward with the bucket curled down. There wasn't supposed to be any rocks that big, but lesson learned. This past weekend, I was back dragging with bucket curled down. I know it was wrong, but I also knew I was replacing the seals so I wasn't concerned if I broke an already broken seal.

Ok I am confused. I know I have said this before in this post. Why are you so certain you did something wrong that caused this. I know people who do the same thing you describe in land that is very very very rocky. They dont have problems with buckets leaking down on new tractors. I have 50 hours on my montana over half of which is doing exactly what you are describing. I back with my bucket curled down and the front tires lifted off of the ground. If I hit a place where all 4 wheels start spinning I take some pressure off of the bucket. I have not had a problem with mine yet. I know people with other tractors that have been doing that for years with no problems.

 

[john_bud]

Hmmm, I looked at the pictures. The thing that is cut at a 45 degree angle is a wear ring that keeps the metal piston from rubbing on the inside of the cylinder. It is split so that it can expand as it wears. All of the sealing is done by the thin stuff down by the nut. Be nice to that when you are putting it together ....

jb

 

[chanceu]

Ok I am confused. I know I have said this before in this post. Why are you so certain you did something wrong that caused this. I know people who do the same thing you describe in land that is very very very rocky. They dont have problems with buckets leaking down on new tractors. I have 50 hours on my montana over half of which is doing exactly what you are describing. I back with my bucket curled down and the front tires lifted off of the ground. If I hit a place where all 4 wheels start spinning I take some pressure off of the bucket. I have not had a problem with mine yet. I know people with other tractors that have been doing that for years with no problems.

For me, it isn't an issue of simply pushing/dragging with the bucket curled down and slowly stopping because I had too big of a bite. In my case, I had the bucket curled down, moving forward at about half a walking pace, and I hit rock that didn't move that almost stopped the tractor. The bucket edge then scraped over the rock and the bucket sprang back the other direction. I'm pretty sure that these small cylinders on small farm loaders aren't built to withstand that sort of shock. After that, the bucket started slowly leaking down.

Of course, I couldn't see inside the cylinder so I can't say for sure that this shock was the direct cause of the problem. It may have been the straw the broke the camels back so to speak. I don't really see anything in the cylinder, but it may be that something in the cylinder is wearing the seals over time which then allows a significant shock to go ahead and break through. Or it may have been any number of other things, but both times I've had this issue with my bucket leaking down, I can point to a single event after which the problem started.

I do have to put some stock in the fact that my owners manual specifically says not to back drag with the bucket curled down. I assume that also applies to pushing forward. I have read several other posts in which people have said their owners manuals for other manufacturers loaders say the same thing.

Hmmm, I looked at the pictures. The thing that is cut at a 45 degree angle is a wear ring that keeps the metal piston from rubbing on the inside of the cylinder. It is split so that it can expand as it wears. All of the sealing is done by the thin stuff down by the nut. Be nice to that when you are putting it together ....

That may be. I thought is was to much of a coincidence that the splits in both rings were almost identical.