Results 1 to 8 of 8

Thread: Caterpillar D8R Leaking hydraulic oil into transmission

  1. #1
    Junior Member
    Join Date
    Jan 2011
    Location
    stouffville ontario
    Posts
    5

    Caterpillar D8R Leaking hydraulic oil into transmission

    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. #2
    Junior Member firedozer's Avatar
    Join Date
    Mar 2008
    Location
    california
    Posts
    16
    The brake system uses transmission oil. The transmission and implement pumps are piggybacked together. So they could transfer at that point.

  3. #3
    Senior Member
    Join Date
    Jan 2008
    Location
    Wi
    Posts
    1,174
    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. #4
    Site Sponsor AmerIndependent's Avatar
    Join Date
    Nov 2009
    Location
    Riverside, CA
    Posts
    358
    Quote Originally Posted by Red637E View Post
    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.
    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.
    Your heavy equipment powertrain specialists.
    Please visit:
    www.AmericanIndependentInc.com

  5. #5
    Senior Member
    Join Date
    Jan 2010
    Location
    In a van, down by the river
    Posts
    1,023
    Could be the imp pump, steering pump, steering motor. Steering is on left side and imp is on the right.

  6. #6
    Junior Member firedozer's Avatar
    Join Date
    Mar 2008
    Location
    california
    Posts
    16
    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. #7
    Senior Member dblaneyfan's Avatar
    Join Date
    Jan 2009
    Location
    South GA
    Posts
    119
    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. #8
    Junior Member
    Join Date
    Jan 2011
    Location
    stouffville ontario
    Posts
    5
    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!

Posting Permissions

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