Have I got a master cyl problem?

[breitlingboy]

My 320 brakes have always been fantastic on track. I've always heard a slight hiss when depressing the pedal. Up til now I've ignored it as the brakes have been performing great. Since I've replaced a brake line I'm struggling to get that performance back. I've bled the system twice but the pedal is still spongy. I'll give it another bleed tomorrow.

Is the hiss anything to worry about?

[Brianmoooore]

The hiss is air being sucked out of the servo. Sounds normal to me. The soggy pedal is probably air somewhere in the system still.
Keep bleeding, preferably with a pressure bleeder.

[Jesus325iTouring]

I've had two cars where i've replaced a small flexy hose on and not been able to regain good pressure,turned out both times to be the master cylinder at fault.
Quite a coincidence that they both failed whilst doing the same job

[Ritchie]

Sometimes you can damage the master cylinder seals when bleeding the system. If there is any corrosion in the section of the bore that the seal never usually touches, it will damage the seal when the piston is pushed full stroke when bleeding.