Master cylinder or something else?

[Limbo]

Hi guys
Just wanted check, normally i've always known that if you've got leaks of break fluid around the pedal or master cylinder its rooted and it needs to be replaced/resealed.

Now my car while its off the pedal feels very firm, no movement at all.
When the car is on i am able to step the pedal down to the floor.
The brakes still work fine.

I've rebleed the brakes, machined the rotors & have replaced all the pads. Even had the brakes rebleed by a mechanic.
Brakes seem to work great.

Does it sound like the MBC is stuffed or is it the something else?

Not sure if it helps but its an ek4 with ITR front rotors/calipers

[[zeth]]

Shuold check your CLUTCH master cylinder instead...

Your brake sounds fine

[Limbo]

clutch works perfectly, nothing wrong with it at all.

[bennjamin]

Brake pedal should never go that far . Also check your bmc check valve ( hose that goes from bmc to the back of the inlet manifold

[chowdaa]

I'm sorry, have to disagree with the clutch master cylinder, completely different fluid circuit.

Sound like BMC, new brake fluid has a much lower viscosity, allowing it to passed through the old worn BMC/internal cups. When the car is off, the brake booster isn't active and once engine vacuum is present and a pressure differential is created in the booster giving the pedal 5 times more push into the BMC, than when the car is off. A faulty one way valve could only cause a stiff pedal during engine operation in theory.

Take care and check your prop valve is not leaking either.

[Nepolian]

;2687464']Shuold check your CLUTCH master cylinder instead...

Your brake sounds fine

^^WTF??


Brake pedal should never go that far . Also check your bmc check valve ( hose that goes from bmc to the back of the inlet manifold

^^Do what benny says and if still no good, you may have leaky booster....on the assumption that your bmc is good!

[Limbo]

had a look at the check valve, its still one way seems fine.
can't see any leaks either at the prop. valve

maybe could be a leaky booster, any way of fixing that?

[bennjamin]

well possibly the BMC-to-booster seal is bad

loose the BMC ( 2 x 12mm nuts) , get some liquid gasket or similar , smear it on the area that the BMC flattens to. This should seal it abit better.

[Limbo]

cool will give that a go.
I wonder if i can get that seal from somewhere....

[chowdaa]

If that does not fix it.

http://i110.photobucket.com/albums/n81/chowdaa/untitled-2.jpg

It is a basically a direct linkage from the pedal rod to the BMC. Any internal leaks or external will result in a very stiff pedal, dramatically reduced brake performance and possible irregular engine operation. But if you still persist on going in this direction, you can get brake boosters reco'ed.

[bennjamin]

Lim , do u have a itr ( 1 inch ) or ek/dc (15/16) booster ?
Both are quite cheap and fairly easy to find I'd just chuck on another known working and see if that fixes the issue

[Limbo]

i currently have the 15/16 booster, yeah i've i'm getting the ITR booster and MBC from a member, installing it this weekend, hopefully that fixes the problem