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Brake fluid leak when changing shoes?

I replaced the brake shoes on my 99 Altima for the first time yesterday. Never done this job before. It went well except on the driver side, when I was pushing the piston back in to insert the new shoe, a little brake fluid leaked out of the seal on the wheel cylinder. Is this normal? I plan to check the brake fluid level over the next few days to see if it goes down. I'm worried I could have a dangerous leak.


  • Is this normal?

  • Did you open the bleeder screw and allow brake fluid to escape through there instead of pushing brake fluid upstream? Was the brake fluid resevoir cap on tight, trapping pressure within the system?
  • No, I didn't remove a bleeder screw or the reservoir cap. Guess I deserve a dope slap for that. After I saw the brake fluid leak out I went and removed the cap. It didn't seem that tight but it could have been sealed I suppose.
  • The brake fluid cap breaths so that really is not an issue. Chances are as you moved stuff around, you pushed the seal outward a little too far, or the spring inside the wheel cylinder did it for you. The important thing is that after you replaced the shoes and got everything back together, it doesn't leak.
  • You don't want to REMOVE the bleeder screw, you just want to back it out a little bit, allowing brake fluid to escape (preferably through a hose that you've hooked up.)
  • Um, I think what we have is a failure to communicate. First are you talking disc brake pads or drum brake shoes?? Me thinks you are replacing the front pads on the disc brakes. The bleeder screw that we are talking about is on the brake caliper where the pads are installed, not on the resevoir. The idea is not to allow old fluid to be pushed back up the brake line but to exit at the bleeder screw directly at the caliper. At this point the seal on the caliper is leaking. You can make sure the boot is properly in place but its anybody's guess whether or not it will continue to leak. If it does, it will require changing the caliper itself and the brake pads again, and bleeding the brakes.
  • Me thinks he was replacing the shoes on the rear.
  • No brake fluid should leak from a wheel cylinder when the brake shoes are installed. If some does that wheel cylinder requires replacement.

  • edited September 2011
    I changed the drum brake shoes on the rear. At this point I'm wondering if I should just monitor the fluid level in the reservoir and if it doesn't go down, figure everything is ok; or take it to a mechanic right now and see if I need a new wheel cylinder. Or maybe take the drum off again and check for signs of further leaking?
  • When you replace the shoes on drum brakes, the new shoes force the brake cylinder piston seals to move further into the cylinder. If there is any corrosion or pitting in the wheel cylinder, the seals will be resting on the bad spot and will leak.

    If you are feeling lucky check under the dust boots after a few miles and see if there is more leaked fluid. You may be lucky and the seals may still be sealing. You don't want to let fluid leak out onto the shoes and drums as the shoes will have to be replaced again.

    Follow Testers recommendation and replace the cylinder(s)
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