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Please tell me I did't just fry my bobcats hydraulics!!

Discussion in 'Skid Steers' started by jav, Feb 9, 2013.

  1. baexcavating

    baexcavating Active Member

    Joined:
    Feb 10, 2013
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    Occupation:
    Work like a rented mule to make ends meet
    Location:
    baraboo, wi
    I noticed no one asked if your hyd oil had a lot of foam in it. if so check your seal on the hydro pump. if the seal is bad it will allow the pump to suck in air causing cavitation. just another possibility
     
  2. jav

    jav Well-Known Member

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    Oct 26, 2009
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    Location:
    MA
    Nope - no foam that i could detect on the dip stick (but good thought). And- after I put in 3 quarts, the level is now over full with the arms down and bucket rotated back to level. It seems less likely that I had a low enough oil level to actually run the pump dry.

    It does seem to point to - something just broke.
     
  3. jav

    jav Well-Known Member

    Joined:
    Oct 26, 2009
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    Location:
    MA
    Crewchief-

    I'm rapidly beginning to hate working on the 843! I went to remove pump today since we have another storm coming thursday. Working in the snowy side yard, in the rain- pump removal was going good- too good - until I go for the bottom flange bolt.

    It's obstructed by inlet T and the inlet line is about 1.5" with no apparent way to drain the oil tank or remove the line without dumping large amounts of hydraulic oil on my lawn! I can't see a way to remove it without suctioning the tank out first. Oh yeah- the tank fill port has a mesh screen which prevents me from suctioning out the tank.

    What am I missing? The manual is useless! ANY experienced guidance would be appreciated.

    I'm actually thinking of piercing the hose as a makeshift drain and then replacing the hose but this can't be the appropriate maintenance procedure.
     
  4. huckleberry

    huckleberry Member

    Joined:
    Feb 12, 2013
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    Occupation:
    paver mechanic
    Location:
    mich
    you can use a shop vac to create vacume in your hyd tank so fluid does'nt spill out. put your hose into fill neck and seal it up. take your filter out of your vac. have the hose above hyd tank, so not to suck fluid out. turn on the vac & remove the suction hose. it will keep the oil from comeing out until you can plug the hose.
     
  5. Bobcatdan

    Bobcatdan Well-Known Member

    Joined:
    May 16, 2012
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    241
    Location:
    wisconsin
    Everything is a pain in the ass to do on 40 series even in a nice warm shop. I just shake my head when guys go on and on about how easy the old machines are to work on then one of those new ones with all the electronics on them.
     
  6. jav

    jav Well-Known Member

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    Oct 26, 2009
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    MA
    Pain in the ass is right. The manual procedure says to first raise the arms.... hard to do if the pumps bad! No thought on flange bolt placement for service either! why not put them at 9 and 3 O'clock instead of 12 and 6 O'clock behind components.
     
  7. willie59

    willie59 Super Moderator

    Joined:
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    Occupation:
    Service Manager
    Location:
    Knoxville TN
    Umm, you are talking about Bobcat...who has been know to place fuel pick-up in tank directly below drive pumps. :D
     
  8. jav

    jav Well-Known Member

    Joined:
    Oct 26, 2009
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    Location:
    MA
    *** UPDATE ****

    After inventing some new swear words, I finally got the pump out. As suspected, the splined shaft was snapped off. Luckily, the splined piece came out of the forward drive pump reasonably easy. I suctioned out about 2 gallons Hydraulic fluid from the sump hose (and lost about a quart) so I'm sure the pump never ran dry. I checked the drive pump shaft and it spins when the engine cranks so I'm pretty sure the damage was contained to the gear pump. Hopefully, restoring charge pressure will also cure the drive noise and flakiness.

    I don't think the system was contaminated since the shaft broke outside of the pump. Would you guys still cut apart the filters and purge the system?? Seems like a huge pain.

    I'm pretty sure I'll need to replace the whole pump but it's a shame I can't buy just the shaft and a rebuild kit as the pumps internals seemed strong.
     
  9. big ben

    big ben Senior Member

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    Location:
    Vancouver Island
    Well it goes back to the old question of what caused the shaft to break ? Does the gear pump spin free or is it bound up? If your getting a new pump quickly blow the old one apart to see its internal condition (just be careful that you can reassemble if it's a core).
     
  10. jav

    jav Well-Known Member

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    MA
    good call big ben- the pump is indeed bound up. My understanding is that the pump I can purchase is new (no core required) so I think I will try to disassemble the old and have a look.
     
  11. JDFG1974

    JDFG1974 Active Member

    Joined:
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    Occupation:
    Owner/Operator CLEARING GRADING COMPANY
    Location:
    Southeast / Georgia
    Sounds like the shaft in the pump broke or splines are worn. Does it make noise or anything?
     
  12. jav

    jav Well-Known Member

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    MA
    yeah- I posted an update. The shaft snapped right where the splines begin (outside of the pump). The splined piece was still in the hydrostat drive pump. I opened up the pump yesterday and found that one of the idler gear shaft bushings was worn and the idler shaft and gear tilted sideways and just dug into the aluminum housing and caused the pump to lock up. There was no debrise inside the pump other than some of the aluminum slivers.
     
  13. joeblow

    joeblow Well-Known Member

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    Retired
    Location:
    Victoria B.C.
    Do you have a clam type bucket?If so ,does it have a crossover relief valve?I am not sure about bobcats system but alot of those skids do not ha ve any circuit relief valves in the aux system.If you run the open clam into a curb or something like that you get a huge (20,000 psi ) pressure spike going back to the gear pump which will stop it very quickly.Then it will either snap the shaft like yours or blow a hole in the side of the pump.
     
  14. jav

    jav Well-Known Member

    Joined:
    Oct 26, 2009
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    85
    Location:
    MA
    No clam shell bucket-


    Finally finished it today...almost a grand later and she lives! What a pain! Over $100 for new filters alone! Cut the old ones and they looked decent- i did find a small sliver of aluminum in the hydraulic filter...looks like the same stuff I saw in the failed pump.

    Lets hope this is a long term fix.
     
  15. NCPIPELINE

    NCPIPELINE Senior Member

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    Occupation:
    The Fixer
    Location:
    Raleigh, NC
    Nice post brother, appreciate the info.