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  1. #1
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    SLX loss of hydraulic pressure

    I have a pair of SLX hydraulic discs on my Scott Scale 30 that have performed well for a couple of years now. Recently, though, I experienced what I assume was a sudden loss of pressure in the rear brake such that the lever went almost to the handle. After pumping the lever for a while, the pressure came back up, but in the few days since it has dropped off again. I topped up the reservoir a little, but to no effect. When I topped up the reservoir the fluid in there was completely clear.

    The catch is that I cannot see ANY leak in the system. Would it be too small for me to be able to notice?

  2. #2
    Rub it............
    Reputation: frdfandc's Avatar
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    How much fluid did you have to put in? Was it completely empty? Or 1/2 full? Just below the lip?

    I would try bleeding the system first. Classic signs of air in the system.

  3. #3
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    Cheers for the response. The reservoir was half full. Not sure how air could have got in suddenly as I had never fiddled with the brake before it happened. But I have ordered a bleed kit online anyway - will give it a go. If that doesn't work, it will be a good excuse for a brake upgrade!

  4. #4
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    As the pads wear the fluid in the reservoir takes up the space, so the reservoir level drops. It could be that you laid your bike over at this point and that's how the air got into the system. If you can't see a leak then a bleed should fix it.

    I've had the same issue with my older shimano brakes, but topping up the reservoir has fixed it without a bleed.

    Tim

  5. #5
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    Thanks, that's a good theory - I do keep it hanging vertically in the shed - front wheel pointing up - so the air could be getting in that way. Will try the bleed.

  6. #6
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    I did the bleed and despite getting about 1/3 of the mineral oil in the brake and the remaining 2/3 on me, it seems to have worked. Brake is now nice and stiff. Thank you for the advice.

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