01 Yukon brake master cylinder fix

[Ventura139]

Sup all.

So I noticed my pedal going down further than usual so I figured I neeed brakes since it’s been about 2 years. Well I changed all my pads which still had meat on them and my pedal still gradually went down to the floor. So now I thinking it’s the master cylinder. I’ve watched a few dyi videos on changing them out. Any tips or is it something that i would be better off dropping it off with mechanics? I can do basic work like oil, tune ups, brakes and even converted my air ride suspension to traditional shocks.
Thanks for any tips

 

[exp500]

Are you handy with tools? Your problem areas are brake bleeder screws and tubing nuts. Make sure you have a good wrench fit on above. It will probably take 2 quarts to bleed, easier with 2 people.
Put a 2x4 on floor so pedal doesn't go to floor.(ruins master cylinder). Pump brakes slowly 3-4 times full stroke, hold to floor or keep hard pressure on pedal, cycle key to on/off 2-3 times, open bleeder rt rear, close bleeder. Repeat till no air and decent pedal. repeat lt rear. lt front rt front. Refill master often. Do not overtighten lines or bleeders.

 

[DIsney]

Mechanically, it's an easy job. I give it a 1 wrench out of 3. Logistically, a little more difficult. You will need to either get a pressure bleeder or a helper. You may also need to run the ABS bleeding procedure using a scan tool.

 

[Ventura139]

Mechanically, it's an easy job. I give it a 1 wrench out of 3. Logistically, a little more difficult. You will need to either get a pressure bleeder or a helper. You may also need to run the ABS bleeding procedure using a scan tool.

Yeah the whole abs thing is what I was worried about. I might just chuck this one up and let them fix it. Thanks for all the input

 

[fasteddy]

One EASY item you may want to check is the little rubber seals under your brake fluid reservoir.
Look to see if they are or surrounding area is wet, which could indicate a leak.
And GENTLY wiggle the reservoir to see if leaks.......

It should not even leak when wiggled under pressure.....either stepping on the brake pedal or with a powerbleeder (15lbs).

Bad seals can easily cause a spongy or lowered pedal.

And on 15+ year old tahoe/Yuk/Sub , most of the fluid seals are borderline.

 

[Bill 1960]

I recently lifted mine and replaced all the calipers at the same time, so plenty of air was introduced to the system. No issues bleeding it and it didn’t require use of the scan tool.

Use a six point socket on the bleeder screws or get a bleeder wrench. Sometimes they’re stuck on older vehicles and you can round it off with the typical 12 points combination.

 

[wildcatgoal]

There is no process more annoying than brake bleeding IMHO, so I just take any car I need that done to my race car's shop and let someone else do it and happily pay them money. Time is money, y'all.

 

[Ventura139]

That’s what I ended up doing. Win some and loose some.

 

[exp500]

Please EDIT your original post title- Add SOLVED, Thanks.