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Caterpillar D8R Leaking hydraulic oil into transmission

Discussion in 'Dozers' started by Red637E, Jan 3, 2011.

  1. Red637E

    Red637E Member

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    Jan 3, 2011
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    Location:
    stouffville ontario
    Looking for some insight into this problem. This tractor was loosing hydraulic oil with no visible leaks. When we checked the transmission level we found it to be way high. We tend to loose around 2-5 gallons of hydraulic oil into the transmission daily. The only two places that hydraulic oil gets near the transmission is the steering motor and the brakes. I pulled off the steering motor and had it pressure tested and it has no leak down. I'm thinking the only other possibility is a leak on the brake curcuit. Has anyone ever incountered this? Any help would be appreciated.
     
  2. firedozer

    firedozer Member

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    Location:
    california
    The brake system uses transmission oil. The transmission and implement pumps are piggybacked together. So they could transfer at that point.
     
  3. Greg

    Greg Senior Member

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    I had the same thing happen on a D8K. Seal went out where the two pumps mate up to the flywheel housing. Was bleeding from one through to the other. Seems to me that there are two seals there one to seal each pump from the other. I have not worked on anything as new as an R series. Are they still doing it the same way after all of these years?
     
  4. AmerIndependent

    AmerIndependent Site Sponsor

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    This machine has one hydraulic pump and one hydraulic motor either of which can leak into the power train system if the input shaft seals have failed.

    One is the implement pump located on the back of the engine and the other is a motor located under the cab which drives the differential steering. Note that if the seal has failed it is often an indication of a problem in the pump.
     
  5. Lee-online

    Lee-online Senior Member

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    Could be the imp pump, steering pump, steering motor. Steering is on left side and imp is on the right.
     
  6. firedozer

    firedozer Member

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    Location:
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    On the D8R series 2 machines the pumps are mated. We just had to rebuild them, but they were losing oil out the weep hole betreen sections.
     
  7. dblaneyfan

    dblaneyfan Well-Known Member

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    Jan 26, 2009
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    Location:
    South GA
    We have had this happen before on a 7XM s/n, and the shaft seal on the steering motor was leaking.

    It should not be the transmission pump that is piggybacked on the hydraulic pump, there should be a weep hole that prevents oil from forcing through.

    Also, check to make sure that the case drain on your steering pump is not blocked.
     
  8. Red637E

    Red637E Member

    Joined:
    Jan 3, 2011
    Messages:
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    Location:
    stouffville ontario
    Just finished removing the steering pump and found that the input shaft seal had a small slice cut off the edge of the seal. The machine was rebuilt end to end by a dealer in california 850 hr ago

    so it was probably from assembly. There was no trash in the oil and the seal wasn't chewed so the pump should be fine. Re-seal and slide it back in, hopefully that was our culprit.

    Thanks for your Help!