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Brake master cylinder replacement, problem persists


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Horacio77
New User

Aug 17, 2022, 3:47 PM

Post #1 of 8 (179 views)
Brake master cylinder replacement, problem persists Sign In

Ford Focus 2008 MK1, 1.6 L PETROL, 120000 KM
Hello everybody, I have a Focus MK1 1.6 l petrol zetec rocam. Its a south american cheaper version of the zetec motor. But ir runs great. Lately I have been having problems with the brakes, the pedal goes to the floor and then sudenly it works again.
When the engine was turned off, the pedal was hard as a rock, according to some people this means the brake booster is working. I asked, and different people told me I should replace the master cylinder.

So yesterday I tried to bleed the old brake fluid, before changing the master cylinder. I started with the right back wheel. When I opened the bleeder valve, nothing came out. Eventually I took the whole bleeder valve out and nothing came out. The hole on the valve is not clogged and the drum brakes look in excelent condition, no leaks anywhere.
I thought that no fluid came out because the master cylinder is bad.

Today I changed the master cylinder, put some fresh fluid in the deposit and with the help of a bleeding pump, tried to bleed the front left wheel, again nothing came out. I took out the whole bleeder valve. Nothing. The valve is not clogged.

So I tried to test the last bit of the brake line, which is made of rubber, so I disconnected the steel line at the point where it connects with the rubber part, a lot of fluid came out of the steel line. Then I tried to open the line when it connects to the caliper, just 1/4 of a turn, and fluid came out.

The pedal after the master cylinder change still goes to the floor, even when the engine is turned off.

Could some one please tell what is going on with my brakes? Thank you.


Hammer Time
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Hammer Time profile image

Aug 17, 2022, 4:54 PM

Post #2 of 8 (166 views)
Re: Brake master cylinder replacement, problem persists Sign In

Oh, where do I start.........

You have a whole bunch of incorrect assumptions here.


Quote
I asked, and different people told me I should replace the master cylinder.


Not necessarily, could also be the ABS hydraulic unit.



Quote
I started with the right back wheel. When I opened the bleeder valve, nothing came out. Eventually I took the whole bleeder valve out and nothing came out. The hole on the valve is not clogged and the drum brakes look in excelent condition, no leaks anywhere.
I thought that no fluid came out because the master cylinder is bad.


No, it has to be pushed through and the bleeder can be clogged at the bottom.


Quote
Today I changed the master cylinder, put some fresh fluid in the deposit and with the help of a bleeding pump, tried to bleed the front left wheel, again nothing came out. I took out the whole bleeder valve. Nothing. The valve is not clogged.


The master has to be bench bled before going to the wheels.



Quote
The pedal after the master cylinder change still goes to the floor, even when the engine is turned off.


You still don't have the system bled sufficiently. At this point you have probably drawn air into the ABS unit and that will require a lot more bleeding.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Horacio77
New User

Aug 17, 2022, 5:06 PM

Post #3 of 8 (162 views)
Re: Brake master cylinder replacement, problem persists Sign In

Hello Hammer! Thank you for your answer! I dont have ABS. I will try tomorrow to bleed the system.

I didnt know the master cylinder has to be bench bled.

I will look into that.
Thank you!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 17, 2022, 5:10 PM

Post #4 of 8 (158 views)
Re: Brake master cylinder replacement, problem persists Sign In

You can probably do it on the car by just cracking the lines loose and let it gravity bleed until you have steady flow from all lines.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Horacio77
New User

Aug 17, 2022, 5:36 PM

Post #5 of 8 (152 views)
Re: Brake master cylinder replacement, problem persists Sign In

Ok! I saw a video of a guy called Scotty Kilmer, in that video he does that, pushes the pedal to the floor with the lines on the clinder closed and then opens a little bit until fluid comes out, then he repeats 5 times. Thank you!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 17, 2022, 5:40 PM

Post #6 of 8 (150 views)
Re: Brake master cylinder replacement, problem persists Sign In

Scotty Kilmer is an idiot. Some of his advice is just outrageous.
Any method is OK as long as you end with a steady flow.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Aug 17, 2022, 8:56 PM

Post #7 of 8 (132 views)
Re: Brake master cylinder replacement, problem persists Sign In

Scotty is a blast of fun just fun not instructions for much.

A simple system should gravity bleed if not question why. ABS crap or what.

Don't blame parts and do pre prime master cylinders out of box or you just pumped air into the system exactly what you didn't want.

Air in hydraulics doesn't work take the most primal anything it's really like that so do it again you may have wrecked the new master cyl. you probably didn't need in the first place!

Tom



Horacio77
New User

Aug 20, 2022, 10:05 PM

Post #8 of 8 (85 views)
Re: Brake master cylinder replacement, problem persists Sign In

Hello, thank you for your answers. The morning after replacing the mc, I could feel a little braking power. That afternoon I was able to use the brake pump and recovered a lot of air out of the back passenger wheel, 3 to go but doing very well compared to this last weeks, thank you for your help!






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