Zero brakes - SOLVED

[Cellison]

I have searched and read all over the internet with no answers. I have a 2001 GMC Yukon 2wd. Rear brakes were locking up so decided to replace all calipers and new rubber brakes lines to the calipers. That solved the issue of locked up brakes. Now I have no brakes. Replaced the master cylinder and bench bled it before installing. Did nothing so I replaced the brake booster. Again no brakes. Pedal goes straight to the floor. I have bled the brakes well over 5 times and no air comes out. The ABS pump is unplugged as it keeps running when car is off and I need to replace the module. could that be the cause of all this. I am stumped and frustrated.

Thanks in advance for any and all help.

 

[Tahoe14]

@iamdub, @OR VietVet @Fless, @wjburken may be able to help

 

[wjburken]

I have a few questions:

How did you bench bleed the master cylinder?

How are you bleeding the brakes at each corner? Method and sequence.

If you’re using the pedal, are you making sure you don’t press the pedal all the way to the floor?

Is the pedal firm or soft?

Did you make sure you didn’t let the reservoir run low when bleeding the brakes?

If you plug the ABS module back in, what happens?

 

[iamdub]

I have searched and read all over the internet with no answers. I have a 2001 GMC Yukon 2wd. Rear brakes were locking up so decided to replace all calipers and new rubber brakes lines to the calipers. That solved the issue of locked up brakes. Now I have no brakes. Replaced the master cylinder and bench bled it before installing. Did nothing so I replaced the brake booster. Again no brakes. Pedal goes straight to the floor. I have bled the brakes well over 5 times and no air comes out. The ABS pump is unplugged as it keeps running when car is off and I need to replace the module. could that be the cause of all this. I am stumped and frustrated.

Thanks in advance for any and all help.

Are the bleeder screws on the top or bottom of the rear calipers?

If you let air get into the system and into the ABS module, you're gonna have to plug it back in to activate the solenoids or there will be air trapped in them. If it's constantly running, this might actually be beneficial for bleeding if the solenoids for all the brakes are activating. Plug it up to bleed a little, then unplug it again and finish bleeding.

But check them bleeder screws on the calipers first.

 

[Tahoe14]

@Cellison

 

[Cellison]

Wjburken
Followed directions from manufacturer when bench bleeding the cylinder . Started with rear passenger tire first , rear driver side , front passenger last front driver side . Yes using the pedal but pedal is soft never pumps up and gets firm . Never let the reservoir run low . When ABS module is plugged back in it runs

 

[Cellison]

Are the bleeder screws on the top or bottom of the rear calipers?

If you let air get into the system and into the ABS module, you're gonna have to plug it back in to activate the solenoids or there will be air trapped in them. If it's constantly running, this might actually be beneficial for bleeding if the solenoids for all the brakes are activating. Plug it up to bleed a little, then unplug it again and finish bleeding.

But check them bleeder screws on the calipers first.

I will try that tonight, thank you for the response. I’ll update after

 

[Cellison]

I want to thank everyone for the responses and apologize for the delay in me answering. The whole family came down with the flu and I honestly didn’t even realize y’all had posted.

 

[Mudsport96]

I want to thank everyone for the responses and apologize for the delay in me answering. The whole family came down with the flu and I honestly didn’t even realize y’all had posted.

Been there. Hope all get well

 

[Cellison]

Bled the brakes again with the ABS pump running, no air coming out only fluid. The pedal never gets hard no matter how many times it’s pumped with the car off. Not loosing any fluid while car is sitting. No front brakes at all but have no air and only fluid when bleeding, rear brakes work when pedal is to the floor and when bleeding no air comes out just fluid.

 

[iamdub]

Bled the brakes again with the ABS pump running, no air coming out only fluid. The pedal never gets hard no matter how many times it’s pumped with the car off. Not loosing any fluid while car is sitting. No front brakes at all but have no air and only fluid when bleeding, rear brakes work when pedal is to the floor and when bleeding no air comes out just fluid.

Can you post a pic of your rear calipers?

 

[Cellison]

Can you post a pic of your rear calipers?

Driver side

 

[Cellison]

Can you post a pic of your rear calipers?

Passenger side

 

[iamdub]

View attachment 421318
Passenger side

Dammit. Your symptoms match those of calipers installed on the wrong sides which puts the bleeders at the bottom. My next stabs are defective new master cylinder or there's a crap ton of air trapped in it somewhere.

 

[Cellison]

Dammit. Your symptoms match those of calipers installed on the wrong sides which puts the bleeders at the bottom. My next stabs are defective new master cylinder or there's a crap ton of air trapped in it somewhere.

I have gotten 2 master cylinders from autozone. i was thinking of trying again.. maybe 3rd times a charm. After that I am going to remove the abs pump and just completely bypass it. See if that does anything. I have never had this happen before.

 

[exp500]

After bench bleeding Master cylinder, install plugs, install MC. Pedal should be hard. Then continue installation.

 

[Cellison]

Got third master cylinder, bench bleed it until no bubbles when pushing plunger. Installed it. Bypassed abs pump. Still no pedal. With car off it will never get hard. I am completely at a loss.

 

[Fless]

What was the pedal like after you plugged it, before you connected the lines?

 

[Cellison]

What was the pedal like after you plugged it, before you connected the lines?

It’s not firm, as if it’s never depleting the vacuum in the booster. I can easily push the pedal to the floor, when car is on there is 0 resistance. (New booster, MC, rubber brake lines and calipers)

 

[Fless]

I'm confused, which is a fairly normal trait over here.

After the MC was bled, were the output ports plugged (no lines connected) and, if so, what was the pedal like then?