E30 Brake issue

[davepoth]

I'm a bit stuck with my 316. The brakes are really soft and I can't figure out why. It's had a new Master Cylinder, new flexis, and the rear cylinders have been checked by a garage and are fine, but the pedal still has a load of travel and sinks further when the pressure is held.

Does anybody have any idea what else might be wrong?

[phelix]

Master cylinders can be awkward to bleed properly; it may take several goes. Was it primed in any way before installation? If you put the new MC in dry, connect up the lines and then add fluid you can have a devil of a time getting the air bubbles out. How was the system bleed? I assume the system isn't losing any fluid?

[TheEnd]

Pump then sinks would point to a leak somewhere, a couple of pumps then solid points to air in the system.

I'd pump and hold it a few times, let it fall, pump, hold etc, then try and see if you can see anything leaking.

[davepoth]

phelix said:

Master cylinders can be awkward to bleed properly; it may take several goes. Was it primed in any way before installation? If you put the new MC in dry, connect up the lines and then add fluid you can have a devil of a time getting the air bubbles out. How was the system bleed? I assume the system isn't losing any fluid?

Bled that way. But it feels exactly the same as it did before on the old cylinder. I can't see any fluid loss, but then I did spill loads when I was changing it. I took it to a garage to get them to change the flexis partially because I thought I may have bled it wrong, they had a go and couldn't get it any better either.

[phelix]

You say the pedal sinks further when the pressure is held - is this engine on or off? If it does this with the engine on you may have a dodgy servo.

Best way to bleed is with a pressure bleeder attached to the reservoir cap. Gunson Ezi-bleed is cheap and works a treat.