Clark C300-40 Mast Cylinder Help, etc
Close
Login to Your Account
Results 1 to 6 of 6
  1. #1
    Join Date
    Oct 2017
    Country
    UNITED STATES
    State/Province
    New Hampshire
    Posts
    122
    Post Thanks / Like
    Likes (Given)
    98
    Likes (Received)
    24

    Question Clark C300-40 Mast Cylinder Help, etc

    Hello,

    Came across an old Clark C300-40, but it's got a few issues.

    Most important one is that the main mast has small geysers coming out from around the larger seal atop the cylinder. This comes out to several quarts over a fifteen minute period of shuffling things around. At first, the lift didn't leak this bad, but it has gotten significantly worse with light use.

    This is the main problem, as it currently makes an awful mess anywhere it is used.


    Other issues include:

    - No Brakes (no fluid in master cyl, inside is also rusted a bit)
    - Side-shift cylinder spews fluid when engaged

    I spent an afternoon pressure washing decades of grease and oil off of everything.
    From there, I did the following work:

    - Hydraulic oil tank drain and flush
    - Engine oil drain and flush
    - Topped off trans oil (clean and near full already)
    - Replaced main hose feeding mast control valve
    - Filed and gapped points, cleaned plugs
    - New battery, other misc electrical

    Everything else functions well, no strange noises, motor runs quiet and smooth, trans shifts without issue.


    Now, I have read that these multi-stage mast cylinders are a PITA to rebuild and are expensive to find parts for.
    Is there any adjustment of the seals/packing that could tighten up this leak, or is it too far gone at this point?

    I'm willing to try anything, just looking for a little guidance first.


  2. #2
    Join Date
    Feb 2011
    Location
    BFE Nevada/San Marcos Tx
    Posts
    3,219
    Post Thanks / Like
    Likes (Given)
    3184
    Likes (Received)
    2006

    Default

    Pretty sure you are looking at rebuilds, never done a 2 stage cylinder myself so cannot say if its easier/harder. How many hoses feeding main lift cylinder, 1 or 2? If you have a hyd shop nearby they should be able to match up seals, if not then you will have to order and it might be best to order a full kit from Clark, just will need to make sure you get right kit as I'd bet that lift came with a variety of cylinders.

  3. #3
    Join Date
    Jan 2015
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    181
    Post Thanks / Like
    Likes (Given)
    120
    Likes (Received)
    31

    Default

    I had to rebuild my 2 stage mast cylinder on my old Hyster 5K lift. The older seal kits can be hard to locate. I had a shop do mine and it ran about 500 bucks. I removed it, brought it to them, and then installed it.

  4. #4
    Join Date
    Jan 2003
    Location
    Imlay City, Michigan
    Posts
    2,290
    Post Thanks / Like
    Likes (Given)
    135
    Likes (Received)
    289

    Default

    Quote Originally Posted by steamandsteel View Post
    Hello,

    Came across an old Clark C300-40, but it's got a few issues.

    Most important one is that the main mast has small geysers coming out from around the larger seal atop the cylinder. This comes out to several quarts over a fifteen minute period of shuffling things around. At first, the lift didn't leak this bad, but it has gotten significantly worse with light use.

    This is the main problem, as it currently makes an awful mess anywhere it is used.


    Other issues include:

    - No Brakes (no fluid in master cyl, inside is also rusted a bit)
    - Side-shift cylinder spews fluid when engaged

    I spent an afternoon pressure washing decades of grease and oil off of everything.
    From there, I did the following work:

    - Hydraulic oil tank drain and flush
    - Engine oil drain and flush
    - Topped off trans oil (clean and near full already)
    - Replaced main hose feeding mast control valve
    - Filed and gapped points, cleaned plugs
    - New battery, other misc electrical

    Everything else functions well, no strange noises, motor runs quiet and smooth, trans shifts without issue.


    Now, I have read that these multi-stage mast cylinders are a PITA to rebuild and are expensive to find parts for.
    Is there any adjustment of the seals/packing that could tighten up this leak, or is it too far gone at this point?

    I'm willing to try anything, just looking for a little guidance first.

    Never dealt with a multiple stage cylinder…….if your uncomfortable with trying to reseal it, I would take it to a hydraulic shop and have it repaired?

    I did the main cylinder on mine, here’s the thread.

    Hyster S80 XL Main Cylinder Leaking, Questions?

    My steering cylinder is leaking now, it looks like I will be repairing that one shortly!

    Good luck on your repair!

    Kevin

  5. #5
    Join Date
    Dec 2003
    Location
    suburbs of Ann Arbor, MI, USA
    Posts
    13,261
    Post Thanks / Like
    Likes (Given)
    465
    Likes (Received)
    1130

    Default

    I just saw your post, I have some experience with this.

    Bottom line is my mast cylinder was weepy when I got it, after a heavy lift one time it got downright flood-y which made a huge mess.

    I used the Hyster to lift the mast cyl out of the Clark. Its very heavy, I placed it on stout sawhorses, newspaper and heavy plastic as its going to make a giant mess. There's a significant amount of fluid within the cylinder itself, its mostly hollow in there.



    The original seals, all basically U-cup seals were all cracked. I would advise making some special tools using your shop to loosen the end caps of the cylinder, I don't have a pic, but don't resort to hammers and cold chisels as you'll have a giant mess on your hands later. Spend the time to develop a shop-made tool then life gets a lot easier



    I ordered new seals as a kit from Hercules Bulldog, which is now just Bulldog Hydraulics. I had to buy them thru Motion Industries otherwise I would have had to setup a credit account, they had no way to process a credit card...this was 2006-2007 ish. Hercules had an "upgraded seal kit" with some special polyurethane (?) formulation to allow the seals to last even longer, it was minimum extra cost and so I got that. Hercules needed a serial number stamped into one of the mast channels to source the correct kit. I had to go over it with a flashlight to find it, I was expecting little 1/4" characters, as I recall they were around 3/4" characters metal-stamped.

    What I learned after an early disaster is this: its very simple to stretch the U-cup over the rod, but nearly impossible to push it into compression in its gland and not have the internal end-cap threads tear it apart as it passes. My solution to that is pictured. Make a 'thin band" by machining PVC pipes or I made some by silver-brazing standard steel strapping/banding together. Both work, the PVC is a lot easier to buy & machine vs trying to get a precision length of steel strap coiled and brazed.

    The idea is to compress the U-cup into the band, carefully and incrementally using generous clean oil.



    Into this state



    Here's where the internal threads would be chewing away but now they just pass easily by, already under compression.



    Last is to use a round or square rod to carefully tap the seal home, incrementally around the circumference.

    IMG_1203 by Matt Isserstedt, on Flickr

    This is the sum of the parts, the old rings are at left, the green ones were a Clark OEM part, but I ended up using the Hercules blue "upgraded seal kit". I had to develop 4 rings for the 4pc U-cup seals.



    Forklift has run great, lts leaking from other areas now but not the mast cylinder. My other projects were to replace the master cylinder (corroded into oblivion). Replaced the wheel cylinders and brake pads. I found the final drives had greased the previous brake shoes very thoroughly and impressively. My forklift had an "inching pedal" as its described in the manual, its the 'left brake pedal" that's supposed to place the transmission in neutral so the engine can be revved to raise the mast more quickly.

    I removed that pedal and also removed the "shuttle valve", and so I eliminated the fluid pathway that puts the transmission in neutral via fluid-power. I just idle around, rigging, and if I want to rev the engine I can place the transmission selector arm in neutral with the best of them.

    This forklift also has an odd battery (E10 maybe?) and so I keep it on a battery minder a lot of the time to keep it in good condition.

    All of the work over the years has paid off, its reliable and handy as anything in tight spaces, just some drips here and there.

  6. Likes atomarc liked this post
  7. #6
    Join Date
    Jun 2013
    Location
    Northern Il
    Posts
    1,715
    Post Thanks / Like
    Likes (Given)
    879
    Likes (Received)
    1581

    Default

    Quote Originally Posted by bsg View Post
    Never dealt with a multiple stage cylinder…….if your uncomfortable with trying to reseal it, I would take it to a hydraulic shop and have it repaired?

    I did the main cylinder on mine, here’s the thread.

    Hyster S80 XL Main Cylinder Leaking, Questions?

    My steering cylinder is leaking now, it looks like I will be repairing that one shortly!

    Good luck on your repair!

    Kevin
    The big thing about multistage cylinders is that the ones used in dump trunks tend to get bell mouthed due to side loading.

    The two stage cylinder in your fork truck has almost zero side loading so it will not be anywhere as bad as what some people will make it to be.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •