Brake master cylinder or front brake calipers fault?

Asked by Feb 29, 2016 at 04:38 AM

Question type: Maintenance & Repair

Hello, I have a Astra H 2004 and after changed brake fluid (pumping method) the brakes get to the floor! Then I bleed again but din t help so I blocked the back brake hoses with pliers and still the same! Then I try to blocked the front ones booth at the same time and the pedal get hard so I took one plier off and the pedal get to the floor. I try to do the last step on the other side and is the same, with only one plier blocking the hose the pedal still soft! What is wrong with my brakes? No chance to be the ABS hydraulic unit?!

15 Answers


It sounds like you emptied the master cylinder out and may have pump it causing air to be trapped in the master cylinder. The master cylinder would have to be bled out first before hooking the brake lines back on. Now if you were pumping air into the system, the ABS unit can only be bled by a scan tool that has a program to move the pistons in the ABS system for bleeding. Then the rest of the brakes would need to be bled out again.

It s never went empty, that I am sure!


The brake calipers are not leaking are they, and were the calipers removed at all? Are you letting it gravity bleed? Just opening the bleeders up?

Hello, the calipers are not leaking and I din t work on the calipers! Only now changed discs and pads to see if get better, but it din t so I bleed again with sameone inside the car pumping the brakes for me!


Sorry to ask, but I sit behind my screen so I need as much detail on this situation. Can you tell me step by step how you are bleeding the brake system. And can you think of anyway air may have ben introduced into the system. One other thing, was the brake pedal fine before you started this project?

It was very nice before! I try to bleed the brakes 2 diferent ways...first with same one inside pumping the brakes with the bleeder opened and then when the new brake fluid starts to came I teel to close the bleeder. I suspect the master cylinder because when my helper was pumping the brakes, he need to pump to the floor what is not usual for the pedal go so far!?It can damage the seal inside!? 2 time or more...pumping with the bleeder closed and when get pressure he pressed the pedal and I open a second and close again...did this around 3 times X4! For another way I suspect the calipers...but booth?! when I blocked them in front it get hard(pedal)...


See thats what gets me is when you block the front lines you get a hard pedal. When the guy pumps the brakes, does he hold it down until you have the bleeder closed off? And he should not be pushing it to the floor, even when you have the bleeder opened. Your gonna have a brake light come on now until it gets reset. If the brake calipers are not leaking, then that is not the problem.

Yes he hold it down until the bleeder closed off!


You have something going on there that I can't see, maybe check out you tube.

I bought 1 brake master cylinder on e-bay...I will let you know after change.


Make sure and bench bleed it before putting it on!

Hello, I already solved the brake problem. was the master cylinder had some dirt inside and after cleaning and bleeding was ok! So the theory of block the brake pipes to see where is the problem is not 100% right!?


I asked about bleeding the master in the my first post, but you said it was fine. I just moved on to the next thing that could fit your symptoms. So no the problem wasn't in the brake hoses evidently, I should have just stuck to my guns on the master cylinder in the first place. Thats all we can do is go off of the information a persons supplies, as we are not there to look at the problem.

I seed it never went empty!? The only thing it was, now we know, when I was changing the brake fluid, using standart bleeding metod, my colege was pumping deep down the pedal and "released" dirty and it parcial blocked the master cylinder!?


Glad you got it fixed. And ya that is very feasible stirring up some dirt & getting caught up in-between the seals in the master. Have a good one...

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