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  1. #1
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    Oil reservoir plugged

    Hi All,

    I can't get any oil flow between the reservoir and the rest of the system. I need some advise on how to troubleshoot this problem and whether or not this is a concern.

    I have a Shimano Deore LX hydraulic system. While bleeding the rear break I noticed that the flow of oil to and from the reservoir is constricted. There doesn't seem to be any obstruction in the cable or the caliper because squeezing the break lever still activates the pistons normally.

    I first tried bleeding from the reservoir. First I loosen the caliper nipple. Then I squeezed the break lever and as expected oil comes out of the nipple. I then tighten the nipple before releasing the break lever. As I understand, some time after releasing the lever the system should suck some fluid from the reservoir and the level in the reservoir should go down. This does not happen in my case. No fluid is sucked from the reservoir and as a result the pistons won't return to their original position. They remain somewhat retracted inside the caliper.

    I then tried bleeding from the nipple. I inject oil through the nipple and the pistons come out and squeeze the spacer. Continuing to inject more fluid should cause the reservoir level to go up. However, in my case I cannot inject more fluid no matter how hard I press on the seringe.

    Since the second bleeding (from the nipple) made the pistons come out against the spacers, the breaks seem to function. I am wondering if the breaks can be operated like this? If not, then how can I get the oil to flow to and from the reservoir?

    I don't have this problem on my front break. Bleeding from the reservoir makes the level go down, and bleeding from the nipple makes the level come up. But not with my rear breaks.

    Thanks in advance for your help
    Jesus

  2. #2
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    Try leaving the caliper nipple closed while you pump the lever a few times to build up pressure. Then release the lever. But if your technique gets the brakes to work then I think you will be OK.

    As you seem to know how to bleed the front brake it's probably not your technique. It could be your master cylinder (at the lever) or a blocked hose. Perhaps try the front hose on the rear caliper (off the bike) and see if you still have the problem.

    Tim

  3. #3
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    try pushing brake piston back w/ nipple closed, see if you cant get fluid to go to the reservoir that way

  4. #4
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    I tried pumping the lever multiple times with the nipple closed but it didn't help. Assuming the problem is with the master cylinder, can that be fixed or should I just buy new levers ?

    The hose is not the problem as pumping the break lever moves the caliper pistons. I also tried pushing the pistons back and that doesn't work either. On my front break pushing the piston easily forces fluid up the reservoir. But not on my rear break.

    Thanks
    Jesus

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