Bleeding 2001 F'in Brakes

[Nickboudro]

2 days ago: 2001 Silverado Z-71 with 150,000 miles. I was replacing inner and outer tierod ends, bottom ball joints, both front shaft seals, and I had calipers in front sticking, so I replaced both side calipers in front and also brake lines. New pads.$532.00 in parts all together. The master cylinder did not "run dry" as I have read on here. I dont see how I could've gotten air in the ABS thing. (went through almost a quart of brake fluid tryin to regain hard pedal).

I had my wife pump the brakes for me, RR, LR, RF, LF...Did all 4 wheels like fuckin 5 times. made sure the master C was full after each wheel. Still have moderatly mushy pedal, but it is sufficient to drive.

Tonight: Different truck-same year 2001 Silverado 2WD with 220,000 miles. Changed rear pads, noticed after I changed them that the calipers werent releasing, probably due to trash behind piston in caliper. I went ahead and changed both calipers and brake lines. No sticky anymore, but when I tried bleeding the brakes same problem. This time (since I didnt fuck with the fronts), I only bled the rears. This truck has a very mushy pedal, not safe to drive. Came home, bled them both 6-8 times each, NO CHANGE!!!!! Again, I used a ton of brake fluid.....

WTF is the problem here? Why is it so God Damn hard to bleed these brakes on these trucks??????????

Also, How do you "gravity bleed" a system? Is it effective? How long does it take to work? Will it work on these ABS systems?

[j cAT]

when bleeding the brakes you must not push on the brake pedal fast..

slowly pump the brakes then when pedal is high after usually 3 pumps not all the way to the floor open bleed screw slowly...only let out an amount that has good flow which is gonna be not too much ,,,then repeat until all air bubbles are gone...also whenever installing new calipers the piston must be fully pushed back..then when depressing the brake pedal again do not pump fast or to the floor easy and slow....

if you pump too fast you create air bubbles,,,cavitation...

I have done this several times on these vehicles ...replacing al these parts no problems ,,as even when the pads are replaced the calipers are bleed....

if the ABS runs dry/air in it then you will need to have the dealer bleed the system as you will need special ABS controller, for the proper bleed proceedure of this componet..

[kahjdh]

If you run the ABS dry I have had success with gravity bleeding them until fluid comes out of all bleeders. To gravity bleed top-off M/C and leave cap off, open all bleeders and wiat until fluid comes out, then close them all off and bleed like normal. After a gravity bleed it doesnt take much to get the rest of the air out.

[Nickboudro]

Originally Posted by kahjdh

If you run the ABS dry I have had success with gravity bleeding them until fluid comes out of all bleeders. To gravity bleed top-off M/C and leave cap off, open all bleeders and wiat until fluid comes out, then close them all off and bleed like normal. After a gravity bleed it doesnt take much to get the rest of the air out.

Thanks that helped a lot I will try this.

Jcat: there was nothing in your post that I found helpful. Everything you stated I already knew. I am not new to bleeding brakes.

Also I did alot of research on here first and I hate it when people post a problem and someone helps, but then the op never posts up on if it worked or not. Not very helpful. I'll be sure to post of this works on mine. Thanks.

[j cAT]

Originally Posted by Nickboudro

Thanks that helped a lot I will try this.

Jcat: there was nothing in your post that I found helpful. Everything you stated I already knew. I am not new to bleeding brakes.

Also I did alot of research on here first and I hate it when people post a problem and someone helps, but then the op never posts up on if it worked or not. Not very helpful. I'll be sure to post of this works on mine. Thanks.

knowing and doing it correctly is something that does not always workout..

you abilities are unknown to me...my experience with these vehicles is very solid especially with these brakes..since 2 vehicles were screwed up I obviously assumed you did not have much knowledge on bleeding/handling this task...

I have bleed much larger braking systems that take gallons of brake fluid with pressurized equiptment and the slower the bleed the higher the brake pressures...

you have air in the system or the master cylinder got damaged when bleeding...

[Nickboudro]

Well I'm going to ignore that assumption.

Well got the truck on blocks, had my bro pump the brakes "Slowly" and bled all 4 calipers AGAIN 5 times per wheel, stopping between every wheel to top off master cylinder. The first time I bled the RR, I had a shot of air come out, and after that nothing but solid liquid in all 4 corners.

No change whatsoever in the pedal. Went through another quart of fluid. I dont see how air could've gotten into the ABS....The calipers were off the truck for maybe a total of 10 minutes before I had the new hoses and calipers bolted back on. Dont see how air could get that far into the system.

[rrousou]

I believe that you require the GM scan tool to properly bleed the brakes with ABS., thus requiring a trip to your local dealer.

[Nickboudro]

Was a defective caliper, was holding air in it. New caliper, hard pedal.

[cramer_77]

another thing to watch for on these trucks not sure if its just the HD's or not but some don't use a vacuum booster, they use a hydraulic booster i think its called, the truck has to be running on these kind setups in order to bleed correctly.