Hyster S80 XL Main Cylinder Leaking, Questions?
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  1. #1
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    Default Hyster S80 XL Main Cylinder Leaking, Questions?

    I have a mid 80's S80 XL that the main cylinder started leaking at the top while using it in really cold weather.....part of the seal can be seen coming out at the top of the gland nut!

    The lift still works and will pick up and not drift down. I was talking to the local Hilo repair guy, he said he would just replace the seals in the gland nut and call it a day? I'm thinking if I have to tear it down this far I should replace all the seals in the cylinder?

    Am I opening up a can of worms if I replace all the seals, should I follow his advice and not go looking for trouble?

    I have the factory manual and parts book, the cost of the parts are reasonable.....it doesn't look terribly difficult or am I missing something?
    I already have the gland nut loose, that was the first hurdle!

    I don't have a business, so the lift being down wouldn't be a problem?

    If you were in my shoes, what would you do?

    TIA for any help!

    Kevin

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    Kevin,

    Rebuilding/resealing the entire cylinder is a big heavy job and it doesn't sound like it's necessary in your case. If you can chain the carriage part way up, drop the lift cylinder down, you should have good access to the gland nut on top and the wiper. Most cylinders I'm familiar with vent their dead side back to the tank via a small hose, and this usually keeps the dead side dry. If you have a return hose make sure it's clear and not kinked or crushed.

    Because your carriage doesn't seem to leak down, it suggests the main seal itself if OK.

    Stuart

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    Quote Originally Posted by atomarc View Post
    Kevin,

    Rebuilding/resealing the entire cylinder is a big heavy job and it doesn't sound like it's necessary in your case. If you can chain the carriage part way up, drop the lift cylinder down, you should have good access to the gland nut on top and the wiper. Most cylinders I'm familiar with vent their dead side back to the tank via a small hose, and this usually keeps the dead side dry. If you have a return hose make sure it's clear and not kinked or crushed.

    Because your carriage doesn't seem to leak down, it suggests the main seal itself if OK.

    Stuart
    Thanks Stuart for the reply!

    I should clarify, my lift has three lift cylinders, one large in the center for the first stage, (I think it's called a free lift mast), two longer cylinders for the second stage, the same as the one in this video.....



    The main cylinder is only about four foot tall, that's why I was thinking it would be easy to replace the seals? I was going to pull the rod out without removing the cylinder from the lift? I have a lift available to help pull the rod out of the cylinder, I can also access the gland nut without removing the cylinder.....hope that makes sense?

    My cylinder only has one line to it at the bottom, there is a return circuit that utilizes the single line? My biggest concern is how hard is it to replace the seals, are there any special tools needed?

    Kevin

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    It likely what you can see is the rod wiper,which serves no more purpose than to wipe the rod.....doh...........however what you are seeing is IMHO polyurethane rot,which sets in and crumbles seals into pieces........this is a charming property of poly U ,and even new unopened plastic blister pack seals will crumble.....So ,if one seal has crumbled ,the rest will soon follow,and a complete stripdown is likely needed........and as you say,Hyster seals cost peanuts.

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    Quote Originally Posted by john.k View Post
    It likely what you can see is the rod wiper,which serves no more purpose than to wipe the rod.....doh...........however what you are seeing is IMHO polyurethane rot,which sets in and crumbles seals into pieces........this is a charming property of poly U ,and even new unopened plastic blister pack seals will crumble.....So ,if one seal has crumbled ,the rest will soon follow,and a complete stripdown is likely needed........and as you say,Hyster seals cost peanuts.
    I don't think the wiper is crumbling, it's still intact just pushed out of the gland nut? I was using the lift truck in 10° farenheit temperatures, I'm sure that didn't help!

    Kevin

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    The opperative seal should be at the bottom of the rod.

    The seal at the top in the nut should just be a dust seal.

    If oil is coming out the top nut - it has gotten past the seal at the bottom.
    THAT is where the trouble should be.

    I htink that I have that same mast on mine.
    We just changed one of the outters a cpl weeks ago, and need to doo the center - as soon as we git time...

    The seal kit is likely Total Source #TSA/HY323896


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    Ox

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    If you are getting oil out the top the piston seal is bad. It’s a single acting cylinder, there should never be oil on the top side of the piston.

    That being said, some lift cylinders don’t have a piston, the rod just goes down into the cylinder. On this setup, all of the sealing is done in the gland nut. If you’ve got a parts manual though, you should have a good idea of what you have.

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    Some times the wiper is pushed out by oil behind it...........if you look it will be double lip........the condition can be cured by cutting away some of the lower lip,so that oil just leaks past the top lip............I ve done this many times with mobile cranes that have scored cylinders and chopped chrome on the lift rams.The wiper still stops dirt and water going into the cylinder.........yes,I dont live in a perfect world of new machines,but I dont go broke every recession either ,dragged down by machine payments.

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    Could someone post a diagram of this "other" style cyl that the top nut hold pressure?
    I'm just not sure that I understand that type?


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    That would be a displacement type ram,which it aint.......anyhoo,around 1965 Hyster went from the simple one way lift ram ,to the common two way ram,....the reason being having the top of the piston "wet" prevented rust forming in the cylinder...........the earlier ram had a drain at the top,open to the air via a tube ......the later one has proper seals and as the ram strokes ,fluid is displaced from the top back to the valve.........this also allows the fitting of a retained pressure type hose burst protection......anti drop system.

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    OK - so it's "wet" but not really carrying any pressure of any kind?


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    depends....if there is a hose burst /anti drop system,the ram cannot fall down under gravity,there must be pressure in the top end of the cylinder to work the valve.These systems are a WHSO requirement for many years.

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    Quote Originally Posted by john.k View Post
    depends....if there is a hose burst /anti drop system,the ram cannot fall down under gravity,there must be pressure in the top end of the cylinder to work the valve.These systems are a WHSO requirement for many years.

    But that would preclude that it is a double acting cyl, wouldn't it?
    You're talking the same system as a chuck actuator.

    You have seen this on the ram of some forktrucks?
    And if so - I would ass_u_me that they have "power down" ability?

    I'd like to have that feature on my snowplow!
    (from the seat of my truck)


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    Stupid design. Single acting cylinder.
    Sometimes you can raise the carriage and chain it to get enough room to work.

    I would change all the seals and the check valve in the piston.
    The check valve can get enough crud in them to start leaking oil thru the piston, and you are back to square one.
    If there is too much oil on the top of the piston, you can force it back to the bottom thru the check valve.
    The cylinder will stop before it is fully extended, keep trying to extend it and if the seals hold, the oil will be forced thru the check valve.
    Usually they just piss oil all over themselves.


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