Hyster 7K lift suddenly leaking at both tilt cylinders... wiper seal...
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  1. #1
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    Default Hyster 7K lift suddenly leaking at both tilt cylinders... wiper seal...

    probably can't tell it in photo below but wiper (dust) seal is cracked pretty bad. Could that alone account for oil pretty much soaking one tire and leaking somewhat on the other... or more likely internal seals kaput as well ? Amazes me that prior to yesterday neither cylinder leaked a drop but all of a sudden they *both* start leaking. (prior to leaks I didn't lift/tilt anywhere near the capacity of the lift truck)

    Also any helpful tidbits on replacing the wiper seal ? i.e. can I loosen the clevis thread clamp and simply unscrew the ram from the clevis in place ?

    img_1567-1.jpg img_1566.jpg

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    The tilt rams are actually under more pressure than the lift.....its strange yours both start leaking at the same time......anyway ,they are the simplest seals to replace........unscrew the cylinder ends,pull out the piston .rod assy,and unscrew the piston nut.....check for a pin or retainer,first,same with the cylinder end.Hyster generally supply a kit with all one cylinder seals,so replace them all.

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    you might also check that the drain line is clear. It's the line (at the top of the cylinder) that just goes to the tank, takes piston seal leakage away. If it gets plugged, you'll have leaks.

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    Quote Originally Posted by greggv View Post
    you might also check that the drain line is clear. It's the line (at the top of the cylinder) that just goes to the tank, takes piston seal leakage away. If it gets plugged, you'll have leaks.
    Tilt cylinders are double acting cylinders...no drain line!

    Stuart

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    Quote Originally Posted by john.k View Post
    ...unscrew the cylinder ends,pull out the piston .rod assy,and unscrew the piston nut...
    Can't tell 100 per cent from the pics but I think this is what you'll have to do. IF the yoke is removable then you
    can replace the seals in the gland without tearing the cylinder down. From what I see in the pic I think the yoke is
    fixed so you're probably faced with a teardown...

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    The yoke is removable but the shaft on that end is threaded. The top cap on the cylinder has several O-rings on its ID in addition to the wiper. Typically you ruin the O-rings and the wiper when you try to slide the cap back over the threaded rod for assembly. Sometime you can wrap a piece of shim stock over the threads, grease everything up and have success. The wiper is just that..a wiper. A leak indicates a failed O-ring internally which means pulling the cylinder and rebuilding it.

    It's been years since I've done this so I could be OTL!

    Stuart

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    Quote Originally Posted by LKeithR View Post
    Can't tell 100 per cent from the pics but I think this is what you'll have to do. IF the yoke is removable then you
    can replace the seals in the gland without tearing the cylinder down. From what I see in the pic I think the yoke is
    fixed so you're probably faced with a teardown...
    Looks like the yoke is removable, notice the pinch bolt on the bottom of the yoke?

    I just went thru resealing the main cylinder on my lift, here's the link;

    Hyster S80 XL Main Cylinder Leaking, Questions?

    There were a couple of YouTube videos of repairing the tilt cylinders, that may help?
    The job was straight forward, hardest part was reassembly!

    If you don't feel like tackling the rebuild portion, you could always take the cylinders to a hydraulic shop?

    Good luck,

    Kevin

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    I would make 1000% sure there isn't another reason you have oil where it appears, as the chances of both tilt cylinders suddenly leaking at precisely the same time are astronomical.

    Stuart

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    Take a close look at the shafts.
    The shaft seals need a good surface of they will leak.
    Sometimes the shafts get beat up from chains or other things putting dings and dents in the shaft.

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    Older seals were polyurethane,and you can just about set your clock on poly-U failing ...........the stuff is unbelievably tough new,works on cut or scored cylinders,but after around 25 years,it suddenly turns into crumble .....literally can be crumbled in the fingers..........And I ve seen NOS vacuum sealed poly U components that were crumbly when opened.......not rubbish either ...Caterpillar OEM.........you couldnt beat the old time leather seals for lasting ability.

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    Quote Originally Posted by atomarc View Post
    The wiper is just that..a wiper. A leak indicates a failed O-ring internally which means pulling the cylinder and rebuilding it.
    With this much leakage I suspect you are right...but last year I had a smaller* but annoyingly constant leak on a lift gate cylinder where installing a new wiper did cure the leakage problem.

    *small compared to this Hyster leak but still bad enough I felt the need to put a small bucket under it with each use of the liftgate to keep fluid off the tarmac.

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    when one of my tilt cylinders started leaking i sent it out for repair. after installing it the next day the other one leaked. same scenario with the mast cylinders. they are all the same age.

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    Wiper seals are to keep stuff out and have no ability to keep the oil in, the lip is faced the wrong way. If oil is coming out around the rod, the gland seals are leaking.

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    Wiper seals are often double lipped ,which is annoying,because any fluid leaking will blow them out.......I generally cut a couple of small nicks with a sharp blade to stop this happening.....Many times with mobile crane repairs ,the lift rams are badly scored and dented.and wont seal 100%,so the new wipers must allow a weep of oil past ,or will be forced out.......I might add,you try refitting 4" dia rods and pistone with new seals by yourself while half a dozen millenials look on vacantly ,and refuse to help.


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