Another brake "job".

[cplurbz]

So Im hoping to have some one double check my math here cause I suck at math and need outside reassurance.

Replacing pads and rotors on my 07 tahoe, no issues before hand, just that time. Usin a power..err, vacuum bleeder..or is that a power bleed- its the one with the master cylinder hopper and its own tank that you hook your air compressor up to and it sucks out the dot 3, its one of those. Kept gettin air out the fronts. The backs seem to bleed fine as in the fluid comes out the calipers with no major bubbles. The fronts "percolate" as in a good head of fluid will build then its major Tylenol sized bubbles here and there.

Aight, hooked up an Icon T7, ran thru the ABS autobleed thing, did all 4 brakes one at a time as it instructed while it made its racket as I pushed on the pedal. Still air out the fronts.

Calipers are all right side up with bleeder on top, took off all 4 bleed screws and made sure they had sealant on them, tried the power vacuum bleeder, the ABS autobleed twice, did the bottle method and the buddy system, brake pedal still feels like im steppin on a pack of Kings Hawaiian rolls.

Hypothesis- my masta cylinder has bought the farm and all of the stuff im doin is just spinning my wheels...figuratively and literlly.

So I've come to that conclusion just by googling my brake symptoms like some auto-webMD and everythings tellin me my master cylinder has cancer. Just hoping its not my booster as apparently those are NOT available.

Any point in the right direction is greatly appreciated.

 

[Big Mama]

I had a similar situation and it turned out to be a cracked bleed screw. I couldn’t get it to stop bubbling and went through a bunch of brake fluid so I took it to my indi.

 

[rdezs]

I've always had a lot better luck using the pressure bleeder, like the Motive Power bleeder.

Always had issues using a vacuum bleeder, but never with a pressure bleeder.

 

[strutaeng]

Was the pedal squishy before the pad replacement? If not, it's highly unlikely the MC went out just in the time you started bleeding it.

Why are you bleeding the brake system for pad replacement BTW? Not that it's bad to replace old brake fluid and new fluid into the system, but not required for pad/rotor job.

Follow the other posters advice and hopefully you'll figure it out.

 

[opfor2]

I just did a similar front brake job where I replaced rotors, pads, rubber brake hoses, and bleeder screws. My power bleeder did the same thing as mentioned above and I bleed them three times. BTW I did not put sealant on the new bleeder screws I was not aware that it was necessary.

 

[cplurbz]

Was the pedal squishy before the pad replacement? If not, it's highly unlikely the MC went out just in the time you started bleeding it.

Why are you bleeding the brake system for pad replacement BTW? Not that it's bad to replace old brake fluid and new fluid into the system, but not required for pad/rotor job.

Follow the other posters advice and hopefully you'll figure it out.

I had a seized caliper, back passenger. Upon pushin the piston back into the caliper it became evident as the other three went in without a hitch, that one wasnt happy.

Popped it out and with the seals out and all squeeky clean the piston would stop half way down. Not canked, not sideways, just full stop.

Polished the shit outta the piston and caliper bore, went in smooth, rebuilt with boot and gasket. No leaks.

So yea, pushin pads in no bleed needed, but had to bleed and now we're here.

And no, it wasnt squishy before hand.

 

[cplurbz]

All signs pointing to good booster, but bad master cylinder, removed master cylinder and torn down.

You can definitely see the wear in the tube from its 19 years of service. But, you can also see a scratch right thru a wear mark.

To be clear, no tools went that deep up in there, just a lint free right off the roll, soaked in brake clean, and my fingers.

Plunger was also stubborn to remove. Instructions stated to push in with phillips head, remove snap ring, slowly retract and plunger will come out with spring pressure. Yea, no it didnt. Had to do som poppin to get it out.

 

[rdezs]

19 years .... Can't complain about that lifespan.

 

[cplurbz]

Nah not at all, keepin up basic maintenance and with the AFM delete I did a few years back (with fan-TASTIC help from the people on here) I have no doubt this thing will take me to the moon and back.

 

[j91z28d1]

did you say new master isn't available?

there's a theory that says a old master can be fine, but once you open the bleeder and the pedal goes to the floor, the piston goes to a part of the bore it hasn't for 10 years of use and can damage seals. someone said put a brick under the pedal before bleeding. I've never tried it.


as said above. pressure bleeder on tops of the master is the way to go. of course if you happen to let it run low during bleeding, you'll have to bench bleed the master first. also when running the abs bleed, the service manual says to have a pressure bleeder on it. mine is a very picky hybrid setup, but gm had to release a tsb to make sure techs were using a pressure bleeder and setting pressure right, as it's about double the standard setup. can confirm the plastic Reservoir can handle 30psi if needed but check your specs before doing it.

 

[cplurbz]

did you say new master isn't available?

No, a new booster isnt available...like, anywhere. But Ive done my checks and its
good.

there's a theory that says a old master can be fine, but once you open the bleeder and the pedal goes to the floor, the piston goes to a part of the bore it hasn't for 10 years of use and can damage seals. someone said put a brick under the pedal before bleeding. I've never tried it.

I have read that same thing as well, dont know the viability of that claim but I lack the mechanical experience required to call ******** on that.

as said above. pressure bleeder on tops of the master is the way to go. of course if you happen to let it run low during bleeding, you'll have to bench bleed the master first. also when running the abs bleed, the service manual says to have a pressure bleeder on it. mine is a very picky hybrid setup, but gm had to release a tsb to make sure techs were using a pressure bleeder and setting pressure right, as it's about double the standard setup. can confirm the plastic Reservoir can handle 30psi if needed but check your specs before doing it.

I have a haynes manual that only states the buddy method to bleed the brakes. The icon T7 tool just states to start at the driver front and go clockwise one at a time drainin the calipers as it activates the abs while another person pumps the brakes.

Im workin on a pressure bleeder and I'll give the 30psi a go. Thanks.

 

[j91z28d1]

No, a new booster isnt available...like, anywhere. But Ive done my checks and its
good.



I have read that same thing as well, dont know the viability of that claim but I lack the mechanical experience required to call ******** on that.



I have a haynes manual that only states the buddy method to bleed the brakes. The icon T7 tool just states to start at the driver front and go clockwise one at a time drainin the calipers as it activates the abs while another person pumps the brakes.

Im workin on a pressure bleeder and I'll give the 30psi a go. Thanks.

start with 15psi.

one of the other guys will be able to confirm what the shop manaul recommends for the standard trucks. mine being a hybrid, the breaking system is a bit of a nightmare. the master cylinder alone has 7 ports on it lol. so it's an odd ball.

 

[donjetman]

gravity is what I use.

 

[Rocket Man]

So Im hoping to have some one double check my math here cause I suck at math and need outside reassurance.

Replacing pads and rotors on my 07 tahoe, no issues before hand, just that time. Usin a power..err, vacuum bleeder..or is that a power bleed- its the one with the master cylinder hopper and its own tank that you hook your air compressor up to and it sucks out the dot 3, its one of those. Kept gettin air out the fronts. The backs seem to bleed fine as in the fluid comes out the calipers with no major bubbles. The fronts "percolate" as in a good head of fluid will build then its major Tylenol sized bubbles here and there.

Aight, hooked up an Icon T7, ran thru the ABS autobleed thing, did all 4 brakes one at a time as it instructed while it made its racket as I pushed on the pedal. Still air out the fronts.

Calipers are all right side up with bleeder on top, took off all 4 bleed screws and made sure they had sealant on them, tried the power vacuum bleeder, the ABS autobleed twice, did the bottle method and the buddy system, brake pedal still feels like im steppin on a pack of Kings Hawaiian rolls.

Hypothesis- my masta cylinder has bought the farm and all of the stuff im doin is just spinning my wheels...figuratively and literlly.

So I've come to that conclusion just by googling my brake symptoms like some auto-webMD and everythings tellin me my master cylinder has cancer. Just hoping its not my booster as apparently those are NOT available.

Any point in the right direction is greatly appreciated.

I’m not sure what math formula you’re using, but since you admittedly suck at math I’ll help you with that portion of it; I’m a math expert especially when it comes to bleeding brakes. The correct answer is 3.927.This should give you the outside assurance you need. You’re welcome. Let me know when you get the brakes bled using the correct math.

 

[Rocket Man]

Seriously, I’d be willing to bet if you use a pressure bleeder and not a suction bleeder, you’ll fix your issue. Push the fluid through the master and lines, don’t suck it from the bleeders.

 

[Fless]

And as long as we're bleeding them we should consider using DOT4.

 

[cplurbz]

The correct answer is 3.927.This should give you the outside assurance you need.

Dammit, I forgot to carry the 2!

Seriously, I’d be willing to bet if you use a pressure bleeder and not a suction bleeder, you’ll fix your issue. Push the fluid through the master and lines, don’t suck it from the bleeders.

Gonna be usin one today or tomorrow depending weather.

 

[cplurbz]

We got brakes. Home made pressure bleeder with a Harbor Freight pump sprayer, a spare cap from oreillys, and some tubing fittings from work, I was able to pressurize the master cylinder and got a horrific amount of bubbles out the front passenger even tho I started with both the back brakes.

At any rate, pressured all for a good while, puttin 10psi to it, after that I went around and did the normal brake pump method to finish it up and alls in workin order.

Thanks to all for the moral support.

 

[rdezs]

Good to hear you found success! There's nothing out there that beats bleeding brakes with the pressure bleeder. It's so easy, I use it to replace all my brake fluid every 2 years.

 

[mikez71]

Nice job finding the problem, and thanks for sharing it with us!

Summary: Sometimes good parts, are bad. Suction bleeders... suck.