Brake issue - 1997 Chevy Silverado Z71

Discussion in 'Chevy C/K Truck Forum' started by Kohen, Oct 21, 2012.

  1. Kohen

    Kohen New Member

    1997 Chevy Silverado Z71 350 5.7L V8 200k miles

    I'll just get right into the story.

    I'll appreciate it very much if you actually take your time and read all this and try to help me out. Thank you.

    Checked my brake fluid one time. Put the cover back on. Checked it later to find out the seal wasn't sealed right. (I now know to put the seal on the lid THEN put it on the master cylinder haha.)

    I was having some problems with my brakes. Stiff pedal sometimes, then it'd be okay. So I got sick of the problem and my dad seemed to think it was the brake booster. So we went the the junkyard and pulled a booster and master cylinder (PITA), paid $75 and went on our way.

    After we bought it my dad was saying how we should try to do a brake bleed just in case. So we did a brake bleed (it needed one, the fluid was very dirty) and it fixed the problem it seemed. Well that lasted roughly a week and the problem started to come back.

    So I decided to bleed the brakes again. The brake fluid was just a little dirty, but I figured I'd try it. No change this time. The brake pedal is still very stiff especially at first start up. Sometimes I can barely brake unless I push really hard on the stiff pedal.

    So before I go spend a bunch of money on (a) part(s), what do you guys think? Let me know if I need to go further into detail about something.

    BTW, the booster holds vacuum and the check valve is working.

    Thanks again!
  2. Kohen

    Kohen New Member

    Before bed BUMP
  3. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    You picked up a used booster and master cyl and you bleed the system, but I can't tell if you installed the used booster.

    Air in the system will give you a soft pedal, but a hard to push pedal sounds like a lack of vacuum assist. I think the new booster is the right path.
  4. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Did you bench bleed the Master cylinder before installing?
    When you bled the brakes are you using a diagnostic tester for the ABS system?
    Are you bleeding the Bias valve first?
    As far as a booster from the recycling yard goes you never really know if it's good or bad which is why parts of this nature arent recommended for repairs.
  5. Kohen

    Kohen New Member

    Sorry, no I did not install it. I returned it along with the master cylinder.

    Okay, I thought it might have been air. I think I might just have to try a new booster then. Seems to be the way people are telling me on these different forums I'm asking. Thank you

    - - - Updated - - -

    I took the master cylinder off, dumped the fluid out, and gave it a good clean with brake cleaner.
    Not sure what a diagnostic tester for the ABS system is.
    When I bled them, I went pass rear, driver rear, pass front, driver front. The fluid is a lot cleaner now.
    Yeah that's true. I didn't install it though. But I'm thinking I'm just gonna try my luck on a new (used) booster. We'll see what else people have to say. Might just get a new master cylinder too haha.
  6. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Your truck has ABS if you read the repair manual for that year truck I believe it tells you to have a diagnostic tester connected to the truck when bleeding the brake system to cycle the ABS system, otherwise you wont get a good bleed, also if your truck has a Bias or Bypass valve on the rear you need to bleed that before bleeding the rest of the system.
  7. Kohen

    Kohen New Member

    Oh okay. That's interesting. Maybe that's why my fluid got kind of dirty again after only a week. I was kind of thinking it was just because the guy before me never performed a brake bleed and that it was just straight up contaminated.

    But I'm thinking it's my booster because a guy on an other forum told me: "to check the booster:

    -with the engine off, depressed the brake pedal repeatedly to deplete the vacuum reserve

    -keep the pedal depressed and start the engine

    with a properly operating booster, the pedal should sink deeper as the vacuum assists brake apply. A faulty booster won't sink deeper."

    I did that and my pedal didn't move when I started it. Hopefully that's my only problem.. Can't wait to change the booster out. Yay.

    EDIT: When I get a chance, I'll try to find that in my manual to confirm your beliefs. I'm interested in what it says too. I'll have to bleed my brake if I replace my booster anyways, so I'll take a look.

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