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1989 963 breaks stuck on pt2

Mross823 · 2026-02-08 15:38

I recently posted about having my 963 not be able to move due to breaks potentially being stuck on, since then I’ve moved the break spool to “max speed position” with a 5/16 bolt, with no change, I’ve checked charge pump pressure and it’s hard to read on my gauge but static it shows 150 ish psi and then I’m getting pretty well 0 on my break pressure tap when I go into forwards or backwards travel. And my travel motors are getting 2500ish psi. So my question is, do I need to be looking for a screen that is potentially clogged, or am I looking at a potential charge pump issue? I also noted a “u tube” in the machine manual which my machine doesn’t have (pictured below is what’s there instead) just looking for some guidance going forward and where I need to look next. Also I attached a photo of the frame at my rear bumper I have developed a hydraulic leak of some kind near my front bumper and I have no idea where it could be coming from, not sure if this is a related issue, but it just started during my testing on the machine, any input is appreciated thankyou

Replies21
  1. #1pittsburgh cat man2026-02-08 16:04

    First do not tilt the cab with bolt in brake lever and linkage connected. it is made to put brakes on when cab is tilted. here is what you need to do next there is a jic line that goes to the side of the frame (constant bleed valve) plug that line. check pressures again

  2. #2Mross8232026-02-08 16:11

    Which one is it, I see where it goes to the frame right at the final but there are two of them would it be the top or the bottom?

  3. #3pittsburgh cat man2026-02-08 16:17

    On the top of the valve where the brake lever is it goes to the up right on frame

  4. #4pittsburgh cat man2026-02-08 16:19

    This help

  5. #5Mross8232026-02-08 16:25

    Helps alot thankyou, will that release the breaks or is that just testing if it’s leaking by

  6. #6pittsburgh cat man2026-02-08 16:31

    No that will put the brakes on it is for testing do not hold in gear more than 30 seconds then 30 seconds in park I'm concerned about leak at brake (the oil coming out of rear of frame)

  7. #7Mross8232026-02-08 17:43

    Okay I’m going to follow up on this tomorrow morning, also noted the original owner had the left hand drive motor rebuilt and replaced and since then it wasn’t able to move, from talking to him today it sounds like the same issue I have today is there any correlation?

  8. #8pittsburgh cat man2026-02-08 17:50

    Did he happen to say why they did the left motor??

  9. #9pittsburgh cat man2026-02-08 17:59
  10. #10pittsburgh cat man2026-02-08 18:05

    This will probably help on top of motors there is a tap should use about a hundred pound gauge get a reading at full forward and reverse on both motors don’t get too excited if it’s a little over 2 pounds

  11. #11Mross8232026-02-08 18:07

    It was leaking from what I could gather, had a guy pull it off rebuild it and bench test it then when installed back it never moved again,

  12. #12Mross8232026-02-08 18:08

    10-4 I will check in on this as well

  13. #13pittsburgh cat man2026-02-08 18:19

    The plot thickens I'm thinking you are going to see a high pressure on the tap on top of left motor I had a 973 blow a piston out of the barrel after it was rebuilt because they didn't get snap ring seated right but I can't remember if it stopped movement on both sides

  14. #14Mross8232026-02-09 16:13

    so following up, I couldn’t locate a test port on top of my motor but I found one on the side which I would assume would be case pressure, (pic attached) which I couldn’t find another test port on it, my 120psi gauge is broke and needed to be replaced so I tested with my 1,000psi gauge and I could see no movement at full travel if I ordered a new gauge today in case I need to double check psi

  15. #15Mross8232026-02-09 16:18

    Following up I capped line off and tested brake pressure still had 0 then retested charge pressure and I had 200ish

  16. #16pittsburgh cat man2026-02-09 16:56

    Thousand pound is way too high spec is 0-2 a bad leak would be 16-30+ try again when you get the new gauge. And yes that is the case drain

  17. #17Mross8232026-02-09 17:01

    10-4 should be in tomorrow or the day after, what do you think about the brake pressure still being zero I was thinking at full travel should be around 10 of charge psi

  18. #18pittsburgh cat man2026-02-09 17:17

    yes thats what it should be one question is the brake linkage connected? do you have the cab up? If it is connected with the cab up you will have 0 The Cat engineer that had alot to do with the development of the hystats said they made it like that so no monkey could run it around with cab tilted

  19. #19Mross8232026-02-09 17:25

    Yup linkage is disconnected and the 5/16 bolt in threaded in like the book says,

  20. #20pittsburgh cat man2026-02-09 17:33

    One other thing I do remember running into a couple machines that had the tap in wrong port make sure port 35 is in right place

  21. #21pittsburgh cat man2026-02-09 20:00

    another thing for you to check make sure the brake lever (where the 5/16 bolt goes) make sure the key is in the keyway and not in the slot where the clamp bolt is