Chevy Silverado brake help please.

I have a 2000 Chevy Silverado. 4x4. Having brake issues. Like no brakes. It started with the pedal dropping to the floor but still stopping. Then it went full no stop.
I kinda diagnosed a leak in the brake line from the ABS module to the rear wheels. I fabbed a new line and had brake action. Not perfect but brake action. I think it needed a good bleeding.

My master cylinder leaked brake fluid. Until it was empty, several times. I put new rotors, calipers and pads on the back and bled them. Master cylinder ended up empty again. It was leaking. Still had some braking action. Not perfect, but it stopped.

Put a new master cylinder on and zero brake action. I did not "bench bleed" the master cylinder but it is holding the fluid in... as in not leaking it out.

So I guess my question is can that much air get into the system that it actually lose all brakes?

It has 326000 miles on it, still looks ok... andhard to take into a shop now with no brakes....

any advice is welcome.

a reply to: tinner07
I have never lost brakes entirely but,

I have a 2001 GMC Z-71 I had break problems on several years ago and replaced the rear pads but the break pedal still seemed soft. Found out that this is common on this vehicle. I researched air problems in the lines until I was blue in the face and found virtually no information on how to bleed the ABS system. What I did find is to take the truck out onto a dirt road, get up speed ande slam on the breaks making the ABS system work to limit wheel locking. I read that this will bleed air out of the ABS system. I did that several times but the pedal action didn't improve any.

A soft pedal is supposedly common on these trucks.

I'll bet the ABS module needs to be bled.

If you ran the master cylinder dry even once, air gets into the module. Last one that I argued with was a 95. It was a nightmare, which ended in bringing it to a family friend. He's got a computer- plugged it in, pushed a few buttons, bled out like I had a dozen times prior, getting a ton of air out.

Brakes worked great after that.

a reply to: CharlesT

I have read that.... problem is I am back to no brakes... Hard to get it up to speed on a country road lol

a reply to: an325nt

I have heard that... might have to have it towed. Truck is a tank...worth fixing.

a reply to: tinner07

If you did not bleed the master cylinder before putting it on you have gotten air into the ABS module.

Which technically is the actual electrical part (the ABS module) and the hydraulic component, I believe it is called a hydraulic valve assembly.

Unfortunately, at this point you will probably need someone with a Genesis or other computer to hook up to your truck to cycle the valves in the module to get rid of the air.

Helpful Link

Something to remember also on working on vehicles with 4-wheel disc brakes is that rotor thickness is a big deal. The smaller the disc thickness, the lower your petal height.

You can also tow the vehicle to a shop that has a pressure bleeder... it's worth a shot.

As a horrible last alternative, you and a helper can attempt to bleed the brakes manually, but if you have air in the brake module then it probably won't work. You will have to go line by line, from the master cylinder to the ABS block, then out of the ABS block, then bleed the rear line(s) from the block to the flexible line from the body to the rear axle, then the rear brake cylinders. Air compresses a lot easier than liquid, so the more air, the harder it is to get the air out.

The old-fashioned way is to have a helper loosen the bleed screw on the right rear caliper (the longest circuit) and then put his finger on the bleed screw while you slowly pump the brake pedal up and down. The helper's finger on the bleed screw acts as a valve... pressure pushes the fingertip away and releases air/brake fluid, when you release the pedal the bleed screw is closed by the fingertip. Watch the brake fluid level in the master cylinder reservoir. If you can get it to get clean no-air fluid coming out, close the bleed valve and then do the right rear. It will be easier than the first.

Hope that helped...

a reply to: tinner07

Whole system needs bled, not just rear.

You'll want to do this with the battery disconnected as the system will make up the lost pressure in the lines.

a reply to: JinMI

Whole system needs bled, not just rear. You'll want to do this with the battery disconnected as the system will make up the lost pressure in the lines.

Do you think changing the master cylinder , and having the original run dry, would introduce enough air into the system to make 0 brakes?

a reply to: tinner07

If you bled the brakes until the master ran dry, you allowed more air into the system. Any spot in the line which has air will allow the pedal to go to the floor. If your ABS module is functioning properly, you'll also allow air into the front lines.

When bleeding, make sure to keep your master topped off.

a reply to: Lumenari

Unfortunately, at this point you will probably need someone with a Genesis or other computer to hook up to your truck to cycle the valves in the module to get rid of the air.

Yeah, thanks for the reply. Was kinda hoping for better news lol... 325k miles on the truck... I might have to bite the bullet and tow it or put it down lol

a reply to: JinMI

If you bled the brakes until the master ran dry, you allowed more air into the system. Any spot in the line which has air will allow the pedal to go to the floor. If your ABS module is functioning properly, you'll also allow air into the front lines. When bleeding, make sure to keep your master topped off.

Actually I did not bleed the brakes until the MC went dry. It just disappeared.Full tank of brake fluid... empty... no sign of leak... happened several times. no sign of a leak. So if that much air is introduced ino the system, that would make 0 brakes?

a reply to: tinner07

It's necessarily the quantity of the air as much as it can get displaced in each line. Then you compress the fluid/air and it is not allowed to push the caliper closed because the pressure is not great enough.

If you're trying to get out of a sticky situation, you can gravity bleed the brakes.

Fill the master then open all your bleed valves. Watch the master and add fluid as needed and wait for all 4 bleeders to be leaking fluid. Once that happens, tighten and then check the pedal for friction. Pump a quite a few times. If there is not enough to drive safely, repeat.

This should get the vehicle to wherever you wish. I would follow up with Lumenari's post to get it properly done.

I had a similar problem in the past, I take the fuse that runs the abs pump out and it usually works.
The fuse is also for the cruise control too but I don't use it so no big loss there , and I knew how to use brakes before there was abs so again not really a problem for me.
Did it on my 95, and currently on my 99 Tahoe.

a reply to: tinner07

So if that much air is introduced ino the system, that would make 0 brakes?

The tiniest bit of air anywhere in the brake system WILL cause 0 brakes.

I have a 98 z71. Use your parking brake, and downshift. Lock it in 4wd so it stops all wheels. Drive it to a shop carefully when traffic is light.

Also, bleed the brakes. It's not that hard.

originally posted by: tinner07
a reply to: Lumenari

Unfortunately, at this point you will probably need someone with a Genesis or other computer to hook up to your truck to cycle the valves in the module to get rid of the air.

Yeah, thanks for the reply. Was kinda hoping for better news lol... 325k miles on the truck... I might have to bite the bullet and tow it or put it down lol

Wait wait.....

Getitng a scanner hooked up and your vehicle bled shouldn't cost more than 2 shop hours plus shop supplies (the fluid).

So roughly $$200-$250 plus the tow?

It's not time to let go of the rig yet...

Sounds like you got an airlocked master or an airlocked ABS system. When the ABS system gets locked, it is hard to bleed it sometimes if the lines are corroded.

You can bleed the new master on the car by pumping and holding then breaking the lines under the master. I have done that quite a few times, bench bleeding them is something I seem to forget. You can also make a little tube to do it right on the car, just take the lines loose and put bleeding tubes on. Those tubes are cheap, and some master cylinders actually come with them sometimes.

Ok thanks for all the advice. Gonna put a little time into tonight after work.

Thanks to ya'lls advice, I have some brake action again. Don't think it is perfect but enough to get to a pro.

Stopped on my way home from work and bought two short brake lines that fit into my master cylinder. Rolled them up into a 90 degree bend so the would fit and put some clear tubing over those, down into the master cylinder.

It took awhile, lots of air bubbles coming out. Seemed the air bubbles would go back down after releasing the brake... cut the plastic tube shorter and figured out slow pressure.

Bought a vacuum bleeder tool from auto zone... right under harbor freight tools I think. I had to fix it within 10 seconds out of the box but bled the back brakes... all new calipers....
I have brakes. Thanks everybody