The main boom cylinder's on my Hitachi EX200 LC has gone to leaking oil badly and I am looking for some advice regarding putting in new seals. I have heard through the rumor mill that you have to have these replaced by a shop because of some special press to get them apart. Is this correct? I've put seal kit's in lots of small cylinder's before and would be willing to risk messing up a seal kit by trying it myself but don't want to start a project that there is no way to accomplish on my own. I'd appreciate any advice/knowledge you'd care to share. Also, if it does require a special press/tool; do the service trucks usually have this with them or do they simply pull the cylinders and take them back to the shop to repair them? I'm thinking I could at least pull them myself and take them in to the shop to save two service call charges, if they do need to go to the shop for repair. Thanks, Dan
Pull them yourself,but bring them to a shop and be specific about what you want done and what you want to be consulted on. The nut that holds the piston on is torqued well above 3000 ft/lbs if memory serves... Rod seal leaks onn those machines are often traced to erosion of the seal land in the rod guide,which means replacing the rod guide. dont be surprised if this is suggested to you
I've always replace the bushing in the gland every time I've repacked a cylinder. The most common reasons I've seen for leakage on main boom cylinders is over heating of the hydraulic oil first and just plain old age second. When pulling the old packing out they will be found to be brittle. You will find that if the other cylinder hasn't been done recently, it will start to leak soon. Good Luck!
Thanks for the response to my thread. Is the bushing your talking about the seal head which the nut holds on? Also, do you need a special press/tool, something to remove the nut. One of my concerns about attempting to do this repair myself is getting the seal set started back into the barrel once it's ready to go back together. Is there a special tool to accomplish this on a cylinder this large, I'm imagining something like a piston compression sleeve for an engine piston. It can be a real pain to get the seals started down the barrel on a small cylinder and wondering how it's done on one as big and heavy as this one. Any thoughts, advice? Thanks, Dan
Ive done these in the bush but it sucks! Doing it on a proper ram bench with the right torque will guarantee a better rebuild. Also prime the cylinder and cycle it gently after reinstalling it onto the machine. Its not that bad a job but there are many seals in there and yes the end nut is a monster. There isn't much to a ram bench and a deep fryer full of ATF or AW-46 on a low temp works great to warm up seals evenly for installation. If you only have a ram or two to do just take them in and have them done professionally.
when we replace cylinder packing kits we romove the rod from the barrle then remove the nut with a 4foot pipe wrench and a backhoe. most would not recomend this ,but is efective
Some makes of cylinders put a brass wear sleeve in the gland. The gland is the part that holds the cylinder rod into the barrel and is put on the rod before the piston is attached on the end. Most of the cylinders I've had to do used fiber wear sleeves now days instead of brass or bronze ones.