GM Truck Club
THE PREMIER CHEVY TRUCK & SUV FORUM
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Results 1 to 8 of 8
  1. #1

    Cool Brakes acting up. Need advice.

    Hi All,
    I have a Chevy Silverado 2500 HD LT with 92,000 miles on it. Recently I have noticed that when coming to a full stop then releasing the brakes to go again it feels like the brakes are sticking. I have removed all of the calipers and checked for any pads hanging up. All pads and calipers move freely. I have also noticed that when at a stop if I push hard enough I can put the brake pedal to the floor. I am not using a great amount of force but enough to make it happen. Someone mentioned that this could be the hydro booster. Does anyone have any insight? How do I test the hydro booster?
    I appreciate any help.
    Thanks

  2. #2

    Default

    Here are the test instructions that came with my remanned hydro boost:


    1. With engine off, apply and release brake pedal 5 to 10 applications to deplete
    accumulator reserve pressure. With foot slightly pressing brake pedal, start engine.
    Pedal should drop and then push back against your foot.
    2. With engine running, turn steering wheel until lightly against steering stop. After
    5 seconds return wheels to the straight ahead position and turn engine off. Apply and
    release brake pedal. There should be at least one power assisted brake application.
    Start engine and allow accumulator to recharge before moving vehicle.
    3. Test drive vehicle. WARNING: Do not operate vehicle until brake and booster
    systems are functioning properly. There should be one power assisted application.

    Common problems and causes.
    1. Hard pedal - Slipping belt, low pump pressure, restricted system.
    2. Pedal stays down - Contamination in booster.
    3. Long pedal/no pedal - Possible brake hydraulic problem. Block master cylinder ports,
    recheck pedal action. If pedal is firm the problem is beyond the master cylinder.

    I would check out any rubber brake hoses on the truck. You would have to have someone press the pedal to the floor and you look around the truck. I suspect that you may have a rubber hose ballooning when you press the pedal to the floor.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  3. #3

    Default

    even in a brand new truck with hydroboost the brake pedal will go to the floor. totaly normal as long as nothing else is wrong (blown brake line etc). yes you should be able to pump the pedal up stiff with the engine off but as long as its running that pedal will travel.


    what do you thinking the brakes are "sticking"
    "i dont think you got the picture. i got a beautiful picture. this baby happens to have an extra turn of speed, which is the only thing i care about. you dont understnad what happens do you? they make cars. they make 'em exactly the same way. one or two of 'em turn out to be something special. nobody knows why. i know why. i may be kiddin' myself, but i think i can make somethin' out of that sad little bucket of bolts." ~ Tennessee Steinmetz

  4. #4
    Sr. Engineer Dana W's Avatar
    Join Date
    Dec 2011
    Location
    Chuluota, Florida
    Posts
    361

    Default

    There may be some trash in the line blocking the fluid from backing off the caliper pistons. Does it seem to pull to one side? If so, that will clue you which side to blow out first.

  5. #5

    Default Brakes

    Quote Originally Posted by Dana W View Post
    There may be some trash in the line blocking the fluid from backing off the caliper pistons. Does it seem to pull to one side? If so, that will clue you which side to blow out first.
    The brakes are not pulling to one side. They brake evenly. So should I flush the system out with new fluid? It sounds like you guys don't think it's the hydro booster?

  6. #6
    Sr. Engineer Dana W's Avatar
    Join Date
    Dec 2011
    Location
    Chuluota, Florida
    Posts
    361

    Default

    Quote Originally Posted by Firemedic724 View Post
    The brakes are not pulling to one side. They brake evenly. So should I flush the system out with new fluid? It sounds like you guys don't think it's the hydro booster?
    It's hard to say, but with that many miles new brake fluid certainly won't make it worse. Since the brakes stop evenly it is unlikely that both sides will be clogged with exactly the same amount of debris.

    It is possible that your caliper slide/retainer bolts and/or the pad slide area in your calipers can be dry/rusty/dirty. Where the moving parts rub need some sort of lube. There is high temp brake grease that you can apply to the slide bolts and the ends of your pads where they slide on the caliper. Some should be used when the pads are changed.

  7. #7
    Legend

    Join Date
    Sep 2010
    Location
    everett, massachusetts
    Posts
    1,323

    Default

    the pedal to the floor with the engine running would indicate the master cylinder is failing. with the 92,ooomi and how old ??? 6 plus yrs ? I would replace all the brake fluid first. this would require to open the bleed screw and push back the caliper pistons fully then bleed out.. do not push back the pistons then open bleed screw as this pushes the contaminated piston fluid into the ABS contral valve section.

    if the brake effort does not improve after this then replace the master cylinder.

    sometimes the cal pistons will stick at a point in the wear of the brake pad material. I have found the rear piston on some to get bell shaped and stick. contaminated fluid will also cause the seals to swell, then the piston binding as well. it does not take much mineral oil to cause these type issues when brake fluid has this mineral oil get into it.

  8. #8

    Default

    Quote Originally Posted by j cat View Post
    the pedal to the floor with the engine running would indicate the master cylinder is failing. with the 92,ooomi and how old ??? 6 plus yrs ? I would replace all the brake fluid first. this would require to open the bleed screw and push back the caliper pistons fully then bleed out.. do not push back the pistons then open bleed screw as this pushes the contaminated piston fluid into the ABS contral valve section.

    if the brake effort does not improve after this then replace the master cylinder.

    sometimes the cal pistons will stick at a point in the wear of the brake pad material. I have found the rear piston on some to get bell shaped and stick. contaminated fluid will also cause the seals to swell, then the piston binding as well. it does not take much mineral oil to cause these type issues when brake fluid has this mineral oil get into it.
    just remember that even brand new trucks (atleast untill 2010, havent cared to check the newest ones) the pedal WILL go to the floor normally if the vehicle has hydroboost.

    i would still like to know why the OP thinks the brakes are sticking.
    "i dont think you got the picture. i got a beautiful picture. this baby happens to have an extra turn of speed, which is the only thing i care about. you dont understnad what happens do you? they make cars. they make 'em exactly the same way. one or two of 'em turn out to be something special. nobody knows why. i know why. i may be kiddin' myself, but i think i can make somethin' out of that sad little bucket of bolts." ~ Tennessee Steinmetz

Similar Threads

  1. Need Tech Advice for brakes on 4x4 Highrider
    By 09BlkColo in forum Chevy Truck Tech Forum
    Replies: 1
    Last Post: 10-25-2012, 08:45 AM
  2. Need Tech Advice for brakes on 4x4 Highrider
    By 09BlkColo in forum Chevy S10 Forum (GMC Sonoma)
    Replies: 0
    Last Post: 10-24-2012, 10:56 PM
  3. Replies: 0
    Last Post: 06-11-2012, 03:22 AM
  4. 4wd acting up
    By GSXR in forum General Chevy & GM Tech Questions
    Replies: 1
    Last Post: 01-14-2012, 10:07 AM
  5. New Brakes, Rotors and Calipers - Squishier then worn out brakes!!
    By bobbyg35 in forum Chevy Silverado Forum (GMC Sierra)
    Replies: 12
    Last Post: 08-09-2011, 05:47 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •