Help with brakes before I pull my hair out

[cofferson]

You may need a scan tool to bleed abs. module. Had to do on 2007 escalade

Yes, I am using a scan tool to do the autobleed sequence.

 

[j91z28d1]

Just a quick update:

Over the weekend I received a replacement master cylinder and an ABS valve block. ABS valve block is put to the side but on hand in case I need it, can be returned for full refund.

I bench bled the master cylinder perfectly until no compression (realistically just a teeny tiny bit but that's normal) and put it on the truck.

I'm curious about this? I've bench bleed tons of master cylinders. but this doesn't sound familiar? what do you mean by no compression? the internal piston should he compressed completely till it bottoms out. the last little bit of air in that front res is always the hardest to get to.

 

[cofferson]

I'm curious about this? I've bench bleed tons of master cylinders. but this doesn't sound familiar? what do you mean by no compression? the internal piston should he compressed completely till it bottoms out. the last little bit of air in that front res is always the hardest to get to.

Of course. What I mean is I prefer to use a kit with hoses so I can be sure no more air is circulating. I prefer this over the "plug ports and pump until air stops rising into reservoir" method since it never works for me. BUT, when I am done, I remove the hoses and install the provided plugs for installation so I don't have to worry about dripping. Once they are installed I can now also check for any compression which should be none. Basically, bleed master cylinder, plug off ports, now piston can no longer move. If air is still trapped and the plugs are installed, I would be able to compress the piston still. Kind of a clunky explanation sorry..

 

[NardDog]

Consider the caliper pistons could be getting stuck and either rebuild them or get new ones. Edit looks like you might have replaced them already.

 

[j91z28d1]

Of course. What I mean is I prefer to use a kit with hoses so I can be sure no more air is circulating. I prefer this over the "plug ports and pump until air stops rising into reservoir" method since it never works for me. BUT, when I am done, I remove the hoses and install the provided plugs for installation so I don't have to worry about dripping. Once they are installed I can now also check for any compression which should be none. Basically, bleed master cylinder, plug off ports, now piston can no longer move. If air is still trapped and the plugs are installed, I would be able to compress the piston still. Kind of a clunky explanation sorry..

ahh. that makes more sense. I've never capped off a master after bleeding. I just turn them side ways so they don't drip.


and we bleed brakes at work by pumping up the pedal till hard, hold and open so it sprays out hard. sometimes you might have to start the equipment to get a good stream. you might try that. give up on the power bleeder and go old school haha. we don't even have one at the shop. I do have one at home but only because this hybrid's braking system has a specific TSB about bleeding brakes because dealer techs couldn't do it. you need something crazy like 25psi on top of the master to bleed correctly. that would damage a normal plastic master.

 

[cofferson]

ahh. that makes more sense. I've never capped off a master after bleeding. I just turn them side ways so they don't drip.


and we bleed brakes at work by pumping up the pedal till hard, hold and open so it sprays out hard. sometimes you might have to start the equipment to get a good stream. you might try that. give up on the power bleeder and go old school haha. we don't even have one at the shop. I do have one at home but only because this hybrid's braking system has a specific TSB about bleeding brakes because dealer techs couldn't do it. you need something crazy like 25psi on top of the master to bleed correctly. that would damage a normal plastic master.

Well I couldn't get any more air so I went for a drive and the brakes were fine BUT my initial problem of the brakes staying engaged after hard was still present. To be fair almost everything needed replaced anyway because the car sat with my father in law for 2-3 years with brake fluid that was blackish green.

Anyway, I isolated the dragging to the rear right which was toast when I picked it up from dragging. Took it for a test drive with the scan tool and saw that if I brake heavy enough to make the inlet valve in the ABS module activate, the brake will remain engaged until I pump the pedal. If I brake heavy but just under ABS activation. It doesn't stick. So the ABS valve block is probably all corroded and gunked up from sitting and was also what was probably causing my bleeding issue.