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No brakes?

Discussion in 'Truck & Equipment Repair' started by Bossman 92, Nov 24, 2013.

  1. Bossman 92

    Bossman 92 PlowSite.com Addict
    Messages: 1,771

    Alright here's the deal. I have a 97 chevy K2500 that we did brakes on last week and now we have nothing.

    Truck has brand new pads, rotors and calipers on the front. Truck has drums on the back with new shoes, wheel cylinders, and all new springs/adjuster hardware.

    We put it all together and had nothing. We replaced the master cylinder with the same results. We bled lines multiple times before we realized the parts store sold me the wrong master cylinder. Replaced it with the correct one and nothing has changed.

    With the key turned forward (but truck off) you get decent pedal when you bleed the brakes but it sometimes (50% of the time) it slowly sinks to the floor when you push hard. When you turn the truck on it pushes all the way to the floor every time with almost no effort.

    The last time we bled the brakes the with the correct master cylinder on we got no pedal in the shop but when we pulled it outside it seemed a little different. The pedal goes almost to the floor but the truck stops and it stops solid.

    Sorry for the long post but we are out of ideas. The only thing we havent done is the brake booster but everything I have read and heard says if the booster goes bad you cant push the pedal to the floor and you would hear hissing coming from the booster (which we dont)

    Any ideas? Thanks for Any advise you can give.
  2. dieselss

    dieselss PlowSite Fanatic
    Messages: 11,392

    a) have you installed the calipers on correctly? bleeder on top right?!
    b) have you adjusted the rear brakes until they just start to drag on the drums?
    c) bled the master, i.e. bench bled or just installed lines/hoses from the output holes back into the master and pressed the brakes until no air came out?
    d) right rear, left rear, left front, right front that's the order to bleed
  3. 1olddogtwo

    1olddogtwo PlowSite Fanatic
    Messages: 12,174

    I don't know GM product very well anymore so it might useless info, but does the truck have abs? I know on some ford models, a scan tool helps to cycle the ABS to shake the air bubbles out.
  4. JCByrd24

    JCByrd24 Senior Member
    from Maine
    Messages: 232

    ABS is the only thing I can think of as well. If no scan tool, I've found you can get plenty of ABS action with the truck in the air (on a lift or 4 jack stands) and 1 front and 1 rear wheel/tire on and truck running in D. Just release brakes, then slowly engage. The difference in weight between 1 wheel on and off will tweak the ABS out sufficiently to bleed it. Or at least it did on my truck. Replaced all brake lines over the course of a week with no attempt to keep fluid in and then used the above method before taking it to a shop to bleed. Turns out, no need to take to a shop, this method worked great. To be clear, bleed once before, and once after this. Or more as necessary.
  5. kimber750

    kimber750 PlowSite Veteran
    Messages: 4,681

    How are you bleeding the brakes? You could possible have the dreaded hydra-boost system. This system is much easier to bleed with vacuum bleeder. If doing it the old fashion way have the truck running when doing it. This is after you have made sure the rear shoes are adjusted like SS said.
  6. 1olddogtwo

    1olddogtwo PlowSite Fanatic
    Messages: 12,174

    I thought with a disc/drum set up that the rear drums gave the pedal its feel. Whenever I've set the drums, I've over adjusted until the durm wouldnt rotate, then click back a couple.
  7. dieselss

    dieselss PlowSite Fanatic
    Messages: 11,392

    Well yes. If they aren't adjusted properly they will never contact the drum. That means fluid will goto the path of least resistance and a spongy pedal you will have
  8. Khowie644

    Khowie644 Member
    from Maine
    Messages: 93

    If the brake booster was bad it would be firm and hard to push down.
    The pedal slowly sinking to the floor points to master cylinder, but since you already changed that the only thing left is there's air in the system somewhere.
    Buy a gallon of fluid and bleed for a while and see if it gets any better. If not you have a leak in either a caliper or wheel cylinder, wheel cylinder's are usually the typical culprit, they like to pull air in when they go bad and make you chase around looking for a leak.
    Chevy's don't need the ABS "cycle-er" tool, easiest way is to hang it in the air as said above, or drive it down a bumpy road and bleed.
    Last edited: Nov 24, 2013
  9. Bossman 92

    Bossman 92 PlowSite.com Addict
    Messages: 1,771

    a. I think so. I bought 1 side then the next day the other so they should be correct.
    b. yes. rears are adjusted just to the point of dragging
    c. bench bled the master
    d. thats the order we bled everything.

    We gravity bled (open the resivor and open all 4 bleeders for several hours) and let the system bleed itself. And have bled almost 5 qts of fluid thru the system using the 2 man pump and bleed method.

    The guy who works for me just texted me (cause I called and asked about the placement of the rotors)


    THANK you guys so much!
  10. dieselss

    dieselss PlowSite Fanatic
    Messages: 11,392

    Ok. Well bleeders on the top. Then rebleed
  11. Bossman 92

    Bossman 92 PlowSite.com Addict
    Messages: 1,771

    Thanks again. I was at the end of my rope with this. I am not sure I am gonna have this guy work on any more of my stuff. I dont have time to watch every move he makes so this was a good lesson for me