On my Hitachi Ex60 the cylinder that lifts the boom up and down ( the largest of the three) is leeking fluid. Not alot but enough so I want to repack it. This will be my first so hard is it to do?
jmac, you are right to address the leak because if oil is leaking out then dust is also being drawn into the cylinder as well... to repack you will have to remove the head from the cylinder and the piston from the rod and it depends how tricky that is. I don't know Hitachi's well but the head may be retained by bolts which means its easy or it may be threaded in which may be more difficult. The piston may be retained by various means, a ring of bolts, it may be threaded on the rod or it may be retained by a large nut. If you have a parts book or shop manual you should be able to tell if its a job that you could handle yourself or whether you need special tooling. If it is specialized work you may want to take it to a rod shop but be careful 'cos often these guys always want to rechrome, hone and make the cylinder like brand new again rather than just do a mid-life repair. I would take a close look at the rod yourself to see if its scratched or worn because just resealing may not be a long term solution.
The rod loooks good, the head looks to be threaded on. The head has two notches in at 180 degrees and my first issue is what tool to use to spin head off. Can this be done with piston still attached to machine, I think you would have to take piston off first. I just noticed the leak so not very old. I will try a snap a photo. What needs to be replaced, just the o rings. Do I need a press to put back together.
You are probably better off to take the cylinder off and take it to a hydraulic shop that does cylinder rebuilds and repairs. I wouldn't be surprised if you will find getting seals for that cylinder will be tough. The cylinder could be leaking because it has a knicked shaft or the shaft is bent.
jmac, now you say that the head is threaded into the cylinder tube I would be very careful with disassembly. I've seen those cylinders completely destroyed when someone attempts field disassembly. The fine thread can pick up in the tube and cause major damage to the tube by ripping out the threads... that being said if you are careful and prepared you could be OK but be aware of the risk. Like Ford LT said, regarding parts maybe consider ordering seals (and head bushing) from your local dealer, having them on hand and taking it to a specialist.
One of the seals on my Hough's 4" main loader cylinders are leaking. I got an estimate of $1000 too rebuild both. I think I'll still have them do it anyways because I read through the service manual and it appears to be a tedious job on these. I've done the old "tie rod" style cylinders before, which were fairly simple, and had piston seals made of leather I think. Not so with many others though. A guy would hate to have the piston come lose of the rod while in operation.
The guys at hydraulic shops do it every day they can pull a cylinder apart have it rebuilt pretty quick. The big expense is if you need a new rod or if it needs re-chroming. Most excavation contractors have their cylinders sent out to be repaired. You don't want to tempt reparing it yourself and the cylinder fails and the boom drops that may cause a accident.
I would pay to get it done. I've rebuilt small cylinders, but a boom cylinder is much larger and more complicated.
I have 2 stabilizer cy. on my 580, 2 lift cy on the 120, and the stick cy on the 120. The 2 on the 580 I have been told a kind of easy.I think I can get one of our mec. to do it on the side.The 3 on the 120 I think I will have done.I have the luxury of 3 buddies in Seattle who have hyd. shops.I will get a good deal,however one told me for the stick cy. on the 120 usually runs about a grand.If you have a little time,do some shopping around.Price and quality of work are all over the place.
Repacking cylinders are easy, the hardest part is getting the nut off of the rod. The only problem repack job we had was on our boom cylinder on our PC150. We had a 4-1 multipler, a cheater pipe and the backhoe on it and still couldn't get it loose. Had to take it to a shop that had a 25-1 multiplier. Torque specs for the nut was 3,000lbs. When putting the nuts back on, we use loctite and the 4-1.
rino you are right... on your PC150 boom cylinder the head (the part where the wiper and gland seal locates) is retained by bolts making it real easy to disassemble. The one good thing about the big nyloc nut used on older excavators is that they NEVER EVER come loose on the job Newer units use a threaded piston with a retaining screw or a double horsehoe type of arrangement which can be disassembled pretty easily. On jmacs Hitachi the head is threaded into the tube which can be very tricky.
The Wulf of much knowledgeness, here's my cylinders break down. Would you try these yourself, or farm out the job to a shop? The max torque I see is 500ft/lbs on the piston, I can achieve that. That's if I can get it disassembled though. I'm worried about things being unloosenable after all this time, like with rino1494's cylinders. What chew think? I'd like to save $1000, or at least reduce it drastically.:yup :wink2
Jeff, I'm kinda stumped to give you an answer because I haven't come across that type of cylinder before. I would give it a go but I'd want to check the shop manual first. If something is overly tight resist using heat or pounding any component excessively. What machine is it off?
It's off a Hough H30. Both sides were leaking when I bought the machine, but one side had a loose packing nut. Very loose, not even finger tight. I tighten it just alittle more than finger tight and set the setscrews there and it stopped leaking. The other side was tight so I didn't mess with it,and it's still leaking. I don't know if I should back off the set screws and try tightening it some past where the set screws stopped it previously, or go ahead and rebuild both so I know they're right. Tightening the packing nut tighter to stop a leak doesn't seem right to me, but I've not had a cylinder like this before either, so I'm not sure.:beatsme It gives the initial set-up in the repair manual, but I didn't read anywhere that the packing nuts should be tightened down more if a leak starts. The chrome all looked good as far as I could see. I guess I could try rebuilding it myself, and if I get stuck just reassemble everything and bring it too the hydraulic shop.
I do that sort of thing all the time, try myself and if I screw it up then bring it to the shop. Most of the time you can fix it yourself.
that type of cylinder is relatively easy to fix. buy/borrow a spanner wrench so you don't screw up your outter nut. i've seen guys take em off with hammer chisel, and crack them.
Yup, I think I will give it a whirl. Thanks guys!!:thumbsup
Good luck Jeff.:yup And just remember: if you DON'T have parts left over then you didn't fix it right.:bouncegri
I have a Kobelco 200 excavator that i am taking the cylinder off tommorow to have repacked and sealed. I think i will tackle it myself instead. Does anyone know what i am up against as far as a nut on the end of piston rod? Its a 1996 Kob Mark 4 .
The thing to keep in mind with hydraulics is keep things clean so the bench your working on should be clean and wash the outside of the cylinder so you have no chances of getting dirt inside.
Sounds like hydraulic cylinder reseal-fest going on in this forum... seriously I would check with your dealer or consult your parts book before ripping into it and order your parts, seals, head bushing if it has one etc.
:bouncegri But it's the middle of winter, and we're bored.
Just think Jeff the worst thing that could happen is your loader goes
It may do that all on it's own!!:crying :yup
Jeff, nothing a garden hose won't fix.
If it does burn up, and burns my garden hose in the process, then you can get me back for what I said about you're hay when your truck went down in smoke.:yup :bouncegri
Let me know how it goes, we have a 98' Mark IV.
I decided to put it off this week and let it leak becuase we are having such unusual warm weather here in Maine this week. When it cools back down and the ground freezes I am going to tear it down. I hope its do-able and i dont have to take it somewhere.
I haven't done any Kobelco cylinders but have done several Komatsu PC 200 cylinders as well as Cat 235 cylinders. On the PC 200 I think the nut on the polish rod is torqued to 7500 ft lbs. I know if you have a proto 1 1/2 drive ratchet don't set a loader bucket on it. It goes off like a grenade. There'll be ratchet shrapnel everywhere.:bouncegri Anyway I pull the cylinder off the machine , pull the polish rod out of the barrel and re pin it on the machine, that will hold the rod. block it up with 12 by 12s or what ever you have. Make sure you lay rags down so it doesn't scratch it, also block it close to the piston so you don't bend it. Then you have to make a wrench to fit it. I've made several out of old grizzley bars or any thick iron. I've seen some guys by a new nut and torch the old one off. I always though this was a waste because you need to torque it so you might as well figure a way to remove it. I'd post a pic of some of the wrenches I've built but their buried in the snow. I never worried about the perfect torque to reinstall the nut. I try to get it close though. 7500 ft lbs = 750 lbs @ 10' etc. Or you could take it to the dealer.
Thanks for the tip, I will let everyone know how it went. doug
I'm sorry I somehow missed this post. This type cylinder is designed to be tightened if a leak develops. A lot of the big forklifts have these types of cylinders as well as a lot of the older Terex equipment. They have bolts to tighten instead of one big nut but they accomplish the same thing. There is limited movement to them so it depends on how many times they have been tightened before.
Really?! The big packing nut does have three set screws that run through the face and contact the cylinder housing to prevent the nut from moving. I've about 1/4" or more space before the nut will bottom out. So I can just loosen the set screws and tighten it down more then, and reset the screws? The packing must be fairly flexible then, huh? I'll try it, and see if it stops the leaking cylinder's leak. Thanks!
Jeff, I am happy you and I found out how to fix your machine , no problem, I will have to find out how to do mine some other way than this forum. :crying
I have the bad feeling that there may not be an "easy" fix for your style cylinder. I really just lucked out!:yup I have an idea, I'll just un-hijack your thread now that I'm done with it, and we can continue on your cylinders problem.............since I'm done now.:bouncegri I am sorry about that Jmac.
I see what happened now. They were just waiting for that pic to arrive.:wink2
I think your rite, no easy fix for me. Good luck with yours tell us if it works.
Re-Taping Hydraulic lines. Hey Jeff D., You might want to re-tape that line with some good 3M black tape. Looks like the repair in the picture is getting kinda tender.:laugh :bouncegri
:bouncegri Ya like that?! Yeah, it was like that when I bought it. I don't know what's underneith the tape, but they don't leak.:beatsme I'll just replace them. They aren't very long anyways so, ain't no thang!!
AAAAHHHH....I wouldn't bother replacing them buddy...just get some thicker yellow paint and mop it on 'em. It'll seal 'em right up.:thumbsup
I need some help. I have a1991 National Series 500B and the Boom cylinder is leaking oil. I need some directions on removing the cylinder, replacing the seals and putting the cylinder back on. Can anyone point me in the right direction.