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Brake Warning Light: Bad Master Cylinder?

Discussion in 'Chevy C/K Truck Forum' started by OldBlueZ71, Dec 4, 2011.

  1. Scott_Anderson

    Scott_Anderson Member 2 Years 100 Posts

    Well, it sounds like you have eliminated everything else but the master cyl, so that probably is your next step.
  2. Coach24

    Coach24 Rockstar 3 Years 5000 Posts

    Does this model have a vacuum booster? Not sure if it applies but those with vacuum boosters what your talking about is usually the VB valve gave up. Now I havent been wrenching for awhile so not sure if it applies back a few years ago it was an instant fix.
    As far as bleeding did you do it with a power bleeder or just the old fashioned way? Most brake shops will do a flush for under 25 bucks which will clean any contaminants and air from system.
  3. OldBlueZ71

    OldBlueZ71 Member

    Yes, it does have a booster, but I am not familiar with the valve you mentioned, VB? There are two 90 degree fittings on the vacuum line from the booster to the intake manifold, is one of those a check valve?
  4. Coach24

    Coach24 Rockstar 3 Years 5000 Posts

    check valve is the one attached to the booster directly and a line comes into it. usually whitish in color. try that as an inexpensive repair
  5. cooter71

    cooter71 Member

    well heres the thing, if its that little red light for the parking brake...it means that the little button under the dash by the parking brake pedal is stuck...really not that big of a deal, clean it, buy a new one, get the heck over it...whatever you wanna do
  6. OldBlueZ71

    OldBlueZ71 Member

    Uh,...no. You are way off the mark. Same light, different input. Heres the thing, if you have something helpful to say then post it, if you just want to be a smartass, keep it to yourself, get the heck over it.....whatever you wanna do!!!
  7. OldBlueZ71

    OldBlueZ71 Member

    Truck had been sitting for a day when I went to unplug the vacuum line and check the valve. It was still holding vacuum in the booster, so I assumed the valve is still good. Bought a remaned master cylinder today and will install tomorrow.
  8. OldBlueZ71

    OldBlueZ71 Member

    Just wanted to follow up on this. Once it was removed, I could see that the old master cylinder was wet on the back side near the piston, but not leaking enough to run or drip down the vacuum booster. New master installed, system bled....nice firm pedal and no warning light. Driven around a good amount over the last two days and no issues, thanks for the help fellas.

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