'89 Bobcat 743 skid-steer loader

Discussion in 'Heavy Truck & Equipment Forum' started by billr, Jul 7, 2014.

  1. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,774
    Likes Received:
    55
    This isn't exactly "heavy equipment", but it isn't a car/truck or lawn-mower...

    My problem is a hydraulic leak that looks to be in a very inaccessible location. It is on a valve block and may only be an O-ring on a port plug (or even slightly loose plug), but so had to get to that I don't even know where to begin. Does anyone know where to find diagrams for that hydraulic system? Starting with that, I could point out which block it is, so that maybe we could find a P/N for it, or a diagram of its construction. Right now this thing is going through about 1 qt/hr of hydraulic oil (at least!), so is beginning to be an expensive pain to keep in operation. But it looks to me like getting to that block would require pulling the engine/pump unit, I'll buy a lot of oil before doing that...
     
  2. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,774
    Likes Received:
    55
    A bit more info: I now know it is the (directional) Control Valve that operates the front bucket lift and tilt. It is located to the right of the engine flywheel, just below the fuel tank. Anyone know how to get to that beast???
     
  3. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,712
    Likes Received:
    112
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    Hi Bill, this should show you around.

    http://www.tractorpartsasap.net/tractor-parts-catalog-download/2013_Skid-Steer-Loader_Parts-Catalog.pdf

    Once had a hard repair like this. Had to go home and eat and be good with the GF 8) $.02

    Next day, went into the feild, and you know what? Found that fitting in 5 new york minutes. :ROFL

    Hoping to have good corn cob this month :p
     
  4. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,712
    Likes Received:
    112
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    Hi Bill;

    Do you have a back hoe on this???

    Puts more pressure on the PTO :idea:

    Cuz if you do not think about this in the future, you will have other o-ring scrapped. ouch
     
  5. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,774
    Likes Received:
    55
    This may not make a lot of sense, because it is an excerpt from another forum where they know what I'm talking about. But, if you have any suggestions, my sanity is at stake here!

    "Well, this is more of a cry for pity or a rant, I'm not sure how you can help, but here goes: The engine came out easy, the shroud "not so much"; but it's out too, so I have good access to the rear of the control valve. However, the front side (where linkage connects) is buried beyond my reach by three hydraulic lines, especially the -12 one going to the reservoir. I bought some crowfoot wrenches to remove those lines and started out with the connection of the largest one (the -12) where it attaches to the "Block" about 6" in front of the Control Valve. That SOB is so tight all I can do is bend my 1/2" breaker-bar, using a long cheater-pipe on it. There is no rust on there, but I soaked it with some penetrating-oil. I have also heated it with a propane torch and have hammered on the nut flats, trying to get a minute amount of "give" someplace. The only thing I can think of to do now is to cut the nut or cut the hose. Either way I lose the hose, and maybe the fitting into the Block. I don't think a longer cheater-pipe is the answer, as the breaker-bar handle is bending enough that I run out of room to swing it (about 30 deg!). I'm pretty sure much more torque will just ruin the breaker or crow-foot, and that's assuming I could find a way to get more swing. I have also considered fabricating a special wrench that could get a 6-point grip and with a stiffer handle, but sacrificing the hose seems more practical. Any other suggestions?"
     
  6. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,774
    Likes Received:
    55
    Cancel the panic, I got the hose off.
     
  7. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,774
    Likes Received:
    55
    This repair has been "entertaining" me for over two weeks now. Screws that are hard to get to? I laugh at that other thread! There are some 1/4-20 screws holding these valve seals in place that take about an hour each to remove or install. They free-run, no rust or anything like that, just near-impossible to reach. Only four of the screws are that bad, the other twelve might only take 2-20 minutes each. At any rate, I got the seals in the valve, started the B'cat up and discovered a new leak in a hose. Fixed that and ran for a couple of hours and dumped a couple of gallons of fluid. New leaks at the oil cooler and another hose. Fixed those, ran a couple of hours and dumped a couple more gallons. Now there was a leak at one of the new seals I had put in. Maybe I damaged it putting it in? Inspection showed that seal, a lip-seal, had "rolled" in its groove so the lips no longer were in contact with the surface to be sealed.

    Here is the "back story":
    The original seals were "quad" or "X" rings. The seal kit for this valve had both the lip-seals and quad-rings, and the FSM for my particular S/N specifically said to use the lip-seals with my particular valve design. I figured the lip-seals were an "upgrade" to the original.

    I replaced the one "rolled" lip-seal with a quad, and hoped I had installed that one wrong in some way. Ran it for another couple of hours and dumped another couple of gallons. Now it was leaking at the other end of the same valve spool. I removed that failed seal, it had also rolled, and replaced it with a quad; hoping-beyond-hope that I had somehow damaged the second seal moving the spool beyond its normal travel while replacing the first one. Ran it for another couple of hours, dumped another couple of gallons; this time from a different spool.

    Hope was now exhausted for the lip-seals, so I replaced all with the quads. (Much fun with those 1 hr/ea 1/4"-20 screws) The next time I ran it for an hour or so and there were no drips at all! I am cautiously optimistic that this is finally fixed for a while. It was getting to be like a helicopter or race-car, 10-20 hours of maintenance for every hour of use, and lots of oil on the ground. Now you know why there have been no recent posts on my Bronco project...
     

Share This Page