Is there a trick to bleeding the clutch? ('97 540)

[eyesoreracing]

I just replaced the clutch master and slave and I'm having issues bleeding it.

I figured out the fluid reservoir has to be more than half full to feed the clutch master, and after a bunch of air passed through, I have solid fluid coming out the bleed screw, but when I close the screw, I still have no resistance from the clutch pedal, so it feels like there's clearly a lot of air still in there somewhere. What's the trick?

I've never dealt with this kind of vertically-mounted master cylinder before. Seems like air would easily get trapped in the top of the cylinder, but what do I know?

[qcdstick]

If I remember right, when mounted to the trans, the bleed screw isn't the highest point in the slave cylinder. So no matter what you do, you won't get that air pocket out with it mounted that way. You need to take the slave cylinder off, and make some kind of jig (I think BMW sells some $$$ part for this) that holds the slave piston in place to keep it blowing out when not attached to the trans as you pump. Orient the slave cyl so the bleed screw is at the top, and bleed normally.

Not sure about the master cylinder on this car, but some cars I've had, the master cylinder had to be bench bled prior to installation.

[pleiades]

....I figured out the fluid reservoir has to be more than half full to feed the clutch master, and after a bunch of air passed through.....

You need to fill the reservoir, topping it up so that fluid will flow into the rear quarter partition that's reserved for the clutch.

[edjack]

Here's my procedure.

Make sure the rear portion of the master cylinder reservoir is full.

Dismount the slave cylinder, but leave the hose connected. Push the actuator rod all the way in. Let it out slowly. Repeat 3 times. Remount slave cylinder.

Good idea to orient the cylinder so that the hose connection is at the highest position, so the air can be flushed out.

[cnn]

No need for any fancy tricks. Been there done that. I posted the tricks below.
Scroll down and see thread #37:

1998 528i CDV removed!!!!
http://www.bimmerfest.com/forums/sho...=209031&page=2

[eyesoreracing]

Thanks for the advice. I think a few of these tricks might be easier/use less fluid than what I ended up doing (pressure bleeder, plus someone actuating the clutch pedal to stir up the air bubbles and get them to flow out the bleed screw.

Now that I have the hydraulics working again, I'm pretty sure they were fine in the first place, but the actual problem was a broken assist spring. Have a new one on order...

I did take the restrictor out, though, and that, at least, feels a LOT better!

I've also got a nasty creak noise from the bellhousing when the clutch is actuated. Is this a common issue, and if so, what is the ultimate failure mode? I can tolerate the noise, but if things are gonna go south, I want to know...

[JimLev]

It's either the release bearing or the pivot point for the clutch fork.
If it's from the pivot point you may be able to get a bit of lube on it if you remove the slave cylinder. Won't be that easy to do but neither is removing the tranny.