Brake problem

[Sean d]

Right guys, I have had my rear end out and let most of the brake fluid drian, I have bled the life out of to no avail,
Today I was chatting to one of the guys that comes in out place and he tried the pedal, I noticed that every time he pressed it there was a his that ran in tandem with the press and for the length of the press, it is coming from the N/S and gets louder near the rear axle, as the car was on the ground it was just too low to locate it but this seems very odd as I am getting no fliud leaks at all, it definately feels like this is where the pressure from the pedal is going
Any idea's

 

[t-tony]

I think it's servo related Sean.
Can you remove the main vacuum pipe from the servo and plug it. Then see how solid the pedal is.

Tony.

 

[Sean d]

I think it's servo related Sean.
Can you remove the main vacuum pipe from the servo and plug it. Then see how solid the pedal is.

Tony.

I'll have a look tomorrow pal, the hiss is definately underneath, where does the pipe from the servo go mate

 

[t-tony]

The only thing that can "hiss" is vacuum leaking mate, underneath but at the front end, engine bay. The pipe from the servo goes to the inlet manifold.

Tony.

ps. Does the car have a back box with the shut off valve in it? If so that could be the source of the hiss if the vacuum pipe to the back box valve is "open"

 

[Sean d]

The only thing that can "hiss" is vacuum leaking mate, underneath but at the front end, engine bay. The pipe from the servo goes to the inlet manifold.

Tony.

How would that effect the brakes pal, I did have that area apart when I painted the engine bay

 

[t-tony]

The vacuum effect from the manifold is what gives you servo assistance as when you press the pedal the servo vacuum "sucks" the pedal down as well as you pressing.

Tony.

 

[Sean d]

The vacuum effect from the manifold is what gives you servo assistance as when you press the pedal the servo vacuum "sucks" the pedal down as well as you pressing.

Tony.

The problem I have is the pedal feels quite stiff but can be pushed to the stop with pressure, however once the engine is running the pedal goes to the floor with ease

 

[t-tony]

That implies that your getting too much assistance, check that pipe at the back box just to be sure it's blocked off. You have stainless hoses now don't you? Have you had the servo and master cylinder off the car when you did the engine bay?

Tony.

 

[Sean d]

That implies that your getting too much assistance, check that pipe at the back box just to be sure it's blocked off. You have stainless hoses now don't you? Have you had the servo and master cylinder off the car when you did the engine bay?

Tony.

What pipe at the back box, yes I do have braided hoses and no not had the servo or MC off

 

[t-tony]

What pipe at the back box, yes I do have braided hoses and no not had the servo or MC off

See post #4 mate. My Z3 had a vacuum operated flap in one of the tail pipes, if yours has, and it's disconnected/broken that's likely your hissing noise.

Tony.

 

[Sean d]

See post #4 mate. My Z3 had a vacuum operated flap in one of the tail pipes, if yours has, and it's disconnected/broken that's likely your hissing noise.

Tony.

My 2.0l had the vacuum flap on the back box but the 2.8 doesn't, the sound is actually like a squirting sound but can't be as there is no fluid loss

 

[t-tony]

Weird one is this mate. Can you record it and WhatsApp it to me or show us on Saturday?

Tony.

 

[Sean d]

Weird one is this mate. Can you record it and WhatsApp it to me or show us on Saturday?

Tony.

I'm hoping to get it on a ramp tomorrow luch pal

 

[t-tony]

Hope that's helpful mate.

Tony.

 

[Brian H]

You could try putting some different coloured fluid through, this way you know you are definitely bled properly. I do think that the upgraded front brake calipers with the bigger pistons will also change the feel of the pedal. Hope you get it sorted.

 

[the Nefyn cat]

If the pedal goes to the floor, whether the engine's on or off, either you've got a well-dodgy hose which is expanding or there's still air in the system somewhere, being as air is compressible and fluids ain't.

 

[t-tony]

He's fitted stainless steel hoses Mick.

Tony.

 

[the Nefyn cat]

Must be air, then. Could be a tricky one.

 

[Sean d]

He's fitted stainless steel hoses Mick.

Tony.

I most certainly have but there must be air in the system as I can hit the floor with the engine on or off, didn't get it on the ramp today but got it on stands and got under it, I couldn't locate the hiss as I could hear it wherever I was, it seemed to be everywhere underneath.

 

[Sean d]

I was thinking about getting a female union and welding the end sealed, I can themn use it to blank off certain areas, maybe start with both rears and work from there