Clutch help needed (Bill R?)

[TC535i]

So, my girlfriend's clutch petal starts feeling REALLY bad the other day, way too light, and engages just barely above the bottom (pedal completely depressed). We hook it up to a pressure bleeder and bleed the system, get some air out, and it feels fine. Unhook the bleeder, and there's nothing. We try pumping it up to build pressure, but it doesn't really do anything.

Yesterday we replaced the clutch master, thinking it had failed, but still no difference. Slave is new too. It seems like every time we bleed it we get air, but I have no idea where it's coming from...? This must be an air pocket getting in the system, as far as I can tell, but I'm stumped, and the mechanics down at the shop are just as lost.

Any ideas???

-Tim

(btw, this is on the '94 325is with the '95 M3 swap... we looked at AllData, and it said to pull the slave out and compress and depress the piston by hand... still no improvement)

[Jeff N.]

I recall that you are supposed to bench bleed the slave in an inverted position prior to installation. I'd have to check the FSM for sure (don't have it handy at work).

Did you do that?

Maybe someone can corroborate this...?

Jeff

[Bill R.]

slave cylinder and then they fasten a special tool on to it that keeps the pushrod from coming out of the slave.. then once thats held in place they put a pressure bleeder on the master cylinder and turn the slave cylinder so that the bleeder is facing up so all the air bubbles rise to the top of the slave and out the bleeder... They stress the importance of the special tool to hold the pushrod so that when you pressurize the system with the pressure bleeder you don't blow the piston and pushrod out the end..
Something I have always had good luck with on troublesome clutchs that don't want to bleed correctly is to do it like you do the old 230sl mercedes..
they specify that you take a long piece of rubber hose that fits tight over the bleeder valve and raise the car up. Then connect the long hose to the closest front brake caliper bleeder and connect the other end of the hose to the clutch slave bleeder. Then open the caliper bleed screw and the clutch slave bleed screw and have someone push the brake pedal down quickly and firmly..when the pedal is down close the bleeder on the brake caliper and raise the brake pedal.. repeat this just like bleeding brakes.
Its a reverse bleeding method where you're forcing brake fluid from the caliper into the slave and back up through the master into the reservoir.
You're using fluid common to both of them so you don't lose any. or very little.. and the reverse surge sometimes helps to get air out thats trapped.
Its the only thing I have found that works on the 230 and 280sl...

So, my girlfriend's clutch petal starts feeling REALLY bad the other day, way too light, and engages just barely above the bottom (pedal completely depressed). We hook it up to a pressure bleeder and bleed the system, get some air out, and it feels fine. Unhook the bleeder, and there's nothing. We try pumping it up to build pressure, but it doesn't really do anything.

Yesterday we replaced the clutch master, thinking it had failed, but still no difference. Slave is new too. It seems like every time we bleed it we get air, but I have no idea where it's coming from...? This must be an air pocket getting in the system, as far as I can tell, but I'm stumped, and the mechanics down at the shop are just as lost.

Any ideas???

-Tim

(btw, this is on the '94 325is with the '95 M3 swap... we looked at AllData, and it said to pull the slave out and compress and depress the piston by hand... still no improvement)