Brakes, bleeding oddity

[kage]

Ok so my brakes were stuttering in the rear. ABS light has been on for a while, ive assumed dirty sensors. Everything still worked fine. Until recently the stutter under my seat when going downhill. Made me think warped rear rotors. So I replaced all rotors and calipers. Then would get a good pedal bleeding with vehicle off (two person leg workout). Start the vehicle and the pedal has no resistance until the very bottom. So I replaced the master cylinder and hydrobooster. Bench bled the master and after install cycled the power steering. I've bleed 4 bottles through it, no air bubbles are coming out. Still the same. Great pedal with it turned off but no pedal with engine running. I suspect air stuck in the abs but I dont have a fancy scan tool or the ability to drive it and lock up the brakes because I dont trust the brakes at this point. Is there a way to cycle or bleed the ABS without those options? I think my next step might be to start replacing sensors.
Thanks in advance!

 

[OR VietVet]

Based off of what I have read here, your problem does sound like air in the abs system. I believe that the correct scanner needs to be attached to it but as you insinuated, I have heard of others finding a very open space and slamming on the brakes to work the air out of there. If there is another way, someone will chime in.

 

[Scottydoggs]

any chance you put the calipers on the wrong side? bleeders need to be on the top of the caliper when mounted. if on the bottom you'll never get em bled.

 

[wjburken]

With the vehicle running, are you able to pump the pedal and build up pressure?

If you can get pressure, you can certainly do what @OR VietVet suggests and go to a grassy field or gravel road and hit the brakes hard to activate the ABS. Do this a few times and then go home and breed the brakes again.

Seems to give me decent results.

Also, if you don’t want to get all the leg exercise, get a vacuum bleeder like this one from Harbor Freight.

It’s made my life so much easier and I feel it does a much better job of pulling crap and air out of the lines.

 

[rockola1971]

The infamous air stuck in the ABS. Post up on your local FB and see if someone will give you a hand that owns a bidirectional scan tool. Most have access to the Automatic Bleed feature which uses the ABS pump to pump the brakes up and then you just crack the bleeder loose. Its a fast job with the bidirectional scanner.

 

[kage]

With the vehicle running, are you able to pump the pedal and build up pressure?

If you can get pressure, you can certainly do what @OR VietVet suggests and go to a grassy field or gravel road and hit the brakes hard to activate the ABS. Do this a few times and then go home and breed the brakes again.

Seems to give me decent results.

Also, if you don’t want to get all the leg exercise, get a vacuum bleeder like this one from Harbor Freight.View attachment 403416

It’s made my life so much easier and I feel it does a much better job of pulling crap and air out of the lines.

ive got an air lift that i use, but i live in an apartment building in a somewhat sketchy area and dont want to roll out the big air compressor. the little red pancake compressor just doesnt have the capaciy to do much at a time. And My Girlfriend has been patient with the leg excercise while im down under bleeding.

 

[kage]

any chance you put the calipers on the wrong side? bleeders need to be on the top of the caliper when mounted. if on the bottom you'll never get em bled.

yeah theyre on there correctly. well at least the rear is. the front i think is almost center on the rear of the caliper. ill look again, they did have L and R stamped on them. Never hurts to double check stupid mistakes. and 80 hour work weeks tend to give way for that.

 

[Fless]

Motive bleeder; no compressor needed. Easy peasy. Ask @Rocket Man.

 

[2slo4u]

Had the some thing happen to me on my 2010 Tahoe. Went out on a wet road and slammed on about 6 or seven times activating the ABS and problem solved.