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Discussion Starter #1
Hi my brake pedal on 207 sinks to the floor even with engine of when i pump the pedal it does not get hard and just sinks. Theres no fluid leaks anywhere the fluid looks on and not low. Any ideas thought it was master cylinder but surelly when engine of the pedal pumped up should be hard and not sink
 

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Discussion Starter #3
But wouldnt the pedal go hard when the engine is off? I thought it might be the brake servo
 

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I am no expert on brakes, but if there are no external leaks and the fluid level in the reservoir is still on the MAX level line. Then it must be the master cylinder that is not working.

Some clues to this is the colour of the brake fluid, if it is dark brown, then your brake fluid is contaminated, possibly one of the seals on the master cylinder has rotted.
 

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I think all the servo does is increase the braking power, which it can't do if the master cylinder is leaking.
 

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Mine sinks even when engine is of so im usure if its master cylinder or servo
Your problem is nothing to do with the servo.
The servo is just a vacuum tank, all it does is increase the pedal pressure on the master cylinder. What is happening is that the piston seals in your master cylinder are failing and brake fluid is getting past,hence the pedal going to the floor. Get a new cylinder fitted pronto before you have brake failure.

The "hard pedal"your talking about is when everything is working properly.You turn the engine off,pump the pedal a few times to empty the servo vacuum tank and the pedal goes hard.That is normal on every car.

Servo`s very rarely fail,but if it did you will have a hard pedal and no brake assistance,so you would need to press the pedal really hard to make the car stop.
 

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Discussion Starter #11
Ok thank you i just looked through the wheel and the front pads look abit low the sinking pedal wouldnt have anything to do with low pads would it. There not metal to metal just abit low
 

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Low pads are nothing to do with a sinking pedal.
So why not bite the bullet, fit new pads at the same time as a master cylinder,new brake fluid and bleeding the whole system is part of the job.
 

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This is definitely a master cylinder issue. I know because I spent all of last weekend resolving this in my ohter car.

In my case the pedal was hard as rocks due to a vacuum leak (torn diaphragm) in the "brake servo". It caused the pedal to be hard like rocks. I could still stop the car but it took ALL my energy to come to a quick stop.

If it was a bad master cylinder I'd have a pedal sinking as you do. What's happening is the hydraulic fluid is leaking past the seals for whatever reason and isn't compressing properly.

Let us know how it goes
 

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A sinking pedal means there is air in the system - brake fluid is non compressible.

How did you bleed the ABS unit? It can trap air if not pulsed while bleeding.
 

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its ment to be done with software to engage the pump while bleeding (a few vids on youtube using pp2k)

a drained system (air in abs pump) is a pig to get pressure without pump engaged.

can try manual bleed and go hard and fast on brake pedal.
 
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