CAT hydro cylinder fail after a very short time......?

[fastline]

Had a boom cylinder head seal leaking for some time on the 322. Everyone has seen it. I really am not set up at the moment to deal with the extreme torque of the rod nut so I worked with my local hydro shop where I pulled the guts, took them the rod/head assy, they slammed my new seals in, and I thought we were winning. After about 10hrs use, the head was just seeping a touch. I was annoyed but I got stuff to do. Now I am seeing that I am actually back to losing some real oil. Like maybe an ounce a day not even running right now.

Further, I notice the wiper seal is actually driving up! In my mind, I am thinking the main seal is extruding and trying to make an exit. The hydro shop is being insane great and offered to take the whole cylinder and find out what's up but I am nervous they did something damaging in there! Now I guess it could be that oil has been trapped behind the wiper and movement is causing this? IDK! All I know is I have never rebuilt one myself and had these issues. But I do know those CAT seals are insane tight! Way more of a PITA than anything else I have touched.

 

[Welder Dave]

It sounds like the hydro shop will look at it and see what the problem is and fix it. It's not very common but sometimes something just slightly off or even a defective seal could cause a leak. Was everything lubed when you put it back together? I just had a slave cylinder leak because of the tiniest nick in the seal. I don't know why you're so panicked about this and trying to guess what the problem is. Why do say they "slammed" the new seals in? You make it sound like they purposely rushed the job and caused it to leak. You're just causing yourself undue stress. It sounds like a good hydro shop but without the full cylinder they had no way to test it after fitting new seals. Maybe you did something wrong when putting it back together? Most shops won't guarantee their work without pressure testing but respectable shops will look and see if it's something simple and generally fix it for you for little or no charge. Let the hydro shop take a look at it instead of pulling your hair out.

 

[fastline]

Hey, I always stress about stuff! That's what I do! lol I'm not insulting the hydro shop as they seemed to do everything to my request. I didn't call them with the Karen attitude, I even told them I probably have no recourse here but wanted to discuss the issue. They want the whole cylinder this time but I honestly want to be there to see what is found. I just don't usually run into stuff like this, so it puzzles and interests me.

We are always installing "anti extrusion rings", but I've never seen a seal extruded.

But while I am not throwing the hydro shop crap, I did have another ish with them many months back when I was there to try to get a small head seal for another cylinder. The head was obviously fresh out, needed cleaned, and I was just wanting a seal. They stuck it in for me and said "here ya go"! I was like, "I super appreciate but that head is far from clean and there was all sorts of crap in that seal groove. I just don't roll like that.

But they ended up removing the seal, threw the head in the steam cleaner, and reinstalled the seal! I mean! I don't know what to think but I really appreciated their understanding. I would have been fine to just pull the seal and let me walk. If I had a remover tool that small I would have done it.

 

[Welder Dave]

You'll just dig yourself an early grave stressing over stuff unnecessarily. Shops don't have mind readers. Some people are fine with, can you pop this seal in and they just pop the seal in. If you want it cleaned say you want it cleaned. Then there's no confusion. They might have given it to a new employee that never thought to clean it first.

 

[fastline]

Dig an early grave you say??? Ha, trust me, this isn't a guy that gets excited to see the next day.

But on the seal, I guess I should have been more? clear that I DO NOT want you to install it, I just need a new Ucup in hand? I felt like they do the , "if it fits, it ships" sort of deal. Very well could have been the new guy, and I have no ill will there. They tried to make a kind gesture but I needed it right at rain.
Oh well, I was just seeing if anyone had run into a similar failure so soon. Not trying to beat up one of the very few hydro shops we have. But I guess the CAT dealer is only 3mi from there, waiting for that gravy! lol

 

[Welder Dave]

Give the shop a chance. Sometimes it doesn't take very much to cause something not to work right. My Cat engine was professionally rebuilt and the rings didn't seat. $hit happens, don't be so quick to condemn the shop especially when it sounds like they want to help you.

What the heck does that mean you don't get excited to see the next day? Get a cancer diagnosis and you'll change your tune in a hurry.

 

[DD57]

I don't think the inner seal is pushing out against the wiper seal, the inner seals are walled-off from each other.That outer wiper seal is hard to install properly.Some cylinders have small bolts with flat washers to help keep the wiper seal from sliding out of the packing head.I hope they get it straightened out for you.You probably know this already, but when you put the boom cyl. back on,hook up the hoses,then before you install the pin,run the cyl. all the way out,then all the way in,cycle it like this a couple of times.This will make sure all the air is out of the cyl.. Good luck with it, hope everything goes OK.

 

[56wrench]

I always install the steel-backed outer wiper seals with red loctite even if there is an outer snap ring

 

[DD57]

I used to use Cat high strength retaining compound,it acted like a lube,for easier insertion,then held like crazy after it dried.

 

[HarleyHappy]

If I am worried about the wiper seal sliding up i use red locktite and if I’m really worried, like my stabilizer cylinders I just did , I will stipple the base and sides with an automatic center punch. If I’m extremely worried, I will peen or stipple it after the wiper seal is in.
Lol

 

[fastline]

seems the consensus is that the main seal is not extruding and pushing the wiper, the wiper is just coming loose?

Either way, it has to come apart. Cylinder only has like 40hrs on it. There was just very slight dampness when first done. Then it just got to a point it was drooling down the cylinder. I'm sure the oil is just bring in more crap and toasting that seal.


I had them save the old seals for me on the first rebuild as I always want to find the smoking gun and sure enough, those seals were just timed out and were brittle and breaking. I only say that because of this deal. If it was leaking for an unknown reason, rebuilt, then still leaked, that would be a concern.

We will get it out and go from there!

 

[Nige]

seems the consensus is that the main seal is not extruding and pushing the wiper,

It can't. See below. It would have to extrude through a gap that is probably only about 10 thousandths.

Did the shop get the seals 15-17 in the right way round and in the case of 16 & 17 with 17 closest to the wiper seal.? Could the old seals have possibly been in wrong and they simply copied what came out.? If so that could all put additional pressure on the wiper seal.

Second all the tips regarding above the installation of the wiper seal if you want it to stay in place.
My preference would be the Cat High Strength Retaining Compound (aka Loctite 620) and hit it with a centre punch at a few places around the circumference after installation.

 

[fastline]

I have no way of knowing how or what they did in the head as I had them load it up with the new seals and return it to me. I am sort of hoping they will share details or even let me go back and work with them!

Seriously, this is another inch closer to just building a hydro bench.

But my hydro shop is most certainly being helpful. I can't fault them. But I also don't want my stuff damaged.

Let me step off on a tangent. Recently had a turbo seal to do in our box truck. NO WAY was I going to hire that done. Why? Because they would have broken off all the bolts and told me I needed a turbo. I guess I just have trust issues but I used to wrench professionally....

 

[Welder Dave]

You have to learn to accept that even the best professionals can have odd things go wrong without explanation some times. Having an attitude like everyone is out to get you is no way to go through life. Just let the hydro shop look at the cylinder already. If your posts are just going to be a bunch of excuses why no nobody doing any kind of work can be trusted nobody is going to want to help you.

 

[Mechanicsville804]

I have no way of knowing how or what they did in the head as I had them load it up with the new seals and return it to me. I am sort of hoping they will share details or even let me go back and work with them!

Seriously, this is another inch closer to just building a hydro bench.

But my hydro shop is most certainly being helpful. I can't fault them. But I also don't want my stuff damaged.

Let me step off on a tangent. Recently had a turbo seal to do in our box truck. NO WAY was I going to hire that done. Why? Because they would have broken off all the bolts and told me I needed a turbo. I guess I just have trust issues but I used to wrench professionally....

Hey Fastline,

I just want to say it sounds like the cylinder shop is doing right by it, I would go in with a humble attitude and allow them to fix their mistake, I'm sure they will.

 

[Nige]

I’ll add to the above if you want to be sure then be there yourself to see what they find when they pull it apart.

 

[HarleyHappy]

One of the stabilizer cylinders I did is leaking down slowly.
Wasn’t doing that before I took it off. The wiper seal was non existent and the seals were all hard. It took hydraulic power to get the rod out as my SXS was just sliding across the ground with the winch. Took a 5 lb deadblow to get the gland off. Went on like greasy peasy and gland screwed in easy as could be, even would have went past the locking screw.
Being a Case with the 2’ rod, I know the seal kit from Broken Tractor is correct.
Just need to get some junk in there to bind it up a bit, or use it enough to get some real heat in the hydraulics as I just completely purged the sytem.
Kinda like a leaky faucet, fixes itself. lol

 

[funwithfuel]

Back to OP. Did you bleed all the air out before putting her to work? Just asking?

 

[Nige]

Back to OP. Did you bleed all the air out before putting her to work? Just asking?

A very good question. Enquiring minds will be interested in the answer.

 

[fastline]

Back to OP. Did you bleed all the air out before putting her to work? Just asking?

Cylinder was cycled several times very slow, without rod end connected to boom. Cylinder was moved horizontally with ports up to encourage all air to leave.

I did notice the cylinder seemed to be a bit 'tight' in that it seemed to labor the engine a touch and need more stick. This was without eye connected. I suspect that was just the new piston seal as those are stupid tight. The head otherwise moved just fine. No odd behavior during assembly.

I will ask if I can be part of the tear down but i'm sure that won't work out. They are busy and prob don't need me eyeing their work. For all I know, it was something we did!


I will say this, I didn't remove the barrel from the hoe so we had to install that rod horizontally where it sat. Not sure I will do that again. I find that running them vertical, the rod weight alone is usually enough to get the piston in so there is no hammering, just some smooth operating.

I also want to see their hydro bench because I need to get one built. Not that we build all that many, but there is more time wasted driving and moving cylinders when we can prob spare a few hrs and have equipment back running same day.