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bobcat 863 blowing seals in carrier

foolish ยท 2022-08-12 10:32

still working on my 863. the hydrostatic motor carrier blows out the seals twice within minutes of moving it. took to dealer and it happened to them twice also. last time up on blocks it ran ok for 15min. , then when on ground blew out within 5 min. brought it home. took hydrostatic motor apart. looked fine except for 2 of the pistons stuck some from coming out. there was scratches on top and bottom of pistons from rubbing on something? dealer had checked the hydraulic pressure and it was good. is hydrostatic motor bad? anything else that would blow out the seals in carrier? thank you

Replies8
  1. #1heymccall2022-08-12 11:11

    Aint that machine equipped with case drain screens on the drive motors? Pretty sure that my 863G machines were. Shaft seal blowout is always from excess case drain pressure, either from a line restriction or excess internal motor leakage (internal wear).

  2. #2heymccall2022-08-12 11:13

    https://shop.finaldriveparts.com/sh...now-about-case-drain-filters-on-final-drives/

  3. #3foolish2022-08-12 15:23

    i did put a new drain filter in when overhauling this machine. it doesn't even have a hr of time on it, but i will reck it. my hydrostatic motor and carrier is very different from final drive in video. the fluid from hydrostatic motor flow blows the seals in carrier , then into chain case and bubbles out the top of chain case covers.

  4. #4heymccall2022-08-12 16:29

    It's still a piston motor, and, as stated clearly above, it will push oil past the shaft seal if either the drain hose path is restricted or the internal leakage in the motor has a greater volume that the drain hose circuit can handle.

  5. #5foolish2022-08-13 13:57

    i think i screwed up royally. i had to disconnect all the hoses and tubes when i replaced axle bearings and races. i did not mark all the hoses. i took lots of pics but not enough. does anyone have a diagram of which hoses go to which end of drain filter?

  6. #6frg2022-08-16 11:33

    1 drain line, for each motor, to the input of case drain filter.(the output is marked) the output of filter goes to tank or HYD pump body.

  7. #7foolish2022-08-16 14:36

    thank you, i'll try and put it together this weekend. looks like i have 1 to go to tank drain and 1 to go to hyd pump.

  8. #8foolish2022-09-12 11:00

    thanks for all the help. once i got the hyd. lines connected correctly it works great. bruce