bleeding clutch system after clutch master cyl change

[bmwperson]

I have a spec 3+ and I had issues shifting into gear..

When I first installed the clutch it was fine for a 300-400miles, after that I started having issues shifting into gear, so i bleed the system. It was ok for about 100miles, then I bought a slave cylinder. Changed that but didnt help much. Now I just changed the clutch master cylinder and the DAMN thing wont go to gear AT ALL.

I bleed like I have done many other cars, pressure bleeder@15psi, point the slave cylinder bleeder up, open the bleeder nipple.... bleed fine, no airbubbles, but when i try to shift it doesnt go into gear. I repeated the process a few times, including pushing/releasing the plunger on the slave. Didnt help. I pretty much went thru 2 bottles of brake fluid.

Any ideas? I just did the same thing on my buddies car and it worked just fine.

[SQ Bimmer]

Did you pump the clutch pedal after bleeding? Also, there are certain things you have to do when bleeding the slave clutch system...

Here's what you need to do: After bleeding the slave cylinder like you already have, remove your pressure bleeder, unbolt the slave cylinder from the transmission, open the bleed screw on the slave cylinder, and PUSH the rod on the slave cylinder all the way into the slave cylinder, then close the bleed screw, then let the rod release, then repeat until pure fluid comes out a few times.

I know's it's an extra PITA to have to pull out the slave cylinder, and it's a bit of a task fumbling with everything when pushing the rod in and stuff, but you have to do it.

Before you attempt to engage gear with the engine running, pump the clutch pedal 10-15 times or so. Also, make sure your brake fluid reservoir never runs dry.

If this doesn't solve your problem with bleeding, post up in this thread...

[bmwperson]

I have done that before, but just to make sure I did it again. Same result.

[SQ Bimmer]

You did the same thing with the slave cylinder rod?

[bmwperson]

yes, I unbolted the focker and opened the bleeder screw, push the rod, close, let it out. Did that 10 times, 20times pump clutch, same result.
Edit: Thats with the slave bleeder nipple pointing up... so the airbubbles could escape.

[SQ Bimmer]

You need to make sure everything is tight, and make sure that your clutch pedal is moving your master cylinder.

[bmwperson]

you really cant mess that up, the fittings on the master are self sealing as long as the c clip is in there it should be fine and the slave doesnt leak and everything is tight... I know I have air in theire, somehow... cuz when u put the slave into the bellhousing it goes in to easily... the question is how do i get the air out.

The clutch feed is a seperate system correct? meaning there is a gravity feed into the master cylinder where it goes to the master cylinder(when clutch pedal is depressed) then as you push the pedal the piston in the master seals off the feed and compresses whatever is in the cylinder. I looked at the hydraulic system and there is pretty much no places where I can have air pockets sitting around(except the slave when its installed)...

[SQ Bimmer]

When you do the bleeding with the slave cylinder rod, try doing it with the pressure bleeder on, and see if that does it.

Also, maybe try pumping the clutch pedal 10 times with the pressure bleeder on.

You are sure that the clutch pedal is connected to the master cylinder, correct? Also, did you install a brand new clutch when doing all of ths work?

When I installed my clutch and transmission when doing my swap, I actually bent my clutch disk becuase of letting too much weight of the transmission pull on the clutch disk. What it resulted in was I was unable to engage gears without hearing a clunk, and sometimes my car would crawl with the clutch all the way in, 1st gear, no brakes. This showed me symptoms exactly the same as an air bubble in the system, but was in fact an inproperly installed clutch disk which now needs to be replaced, and since I've put 15k miles on it now (clunking stopped after 28 passes at a drag strip, musta worn down the clutch enough...) I probably need to change my friction surface on my flywheel as well as my pressure plate...

[bmwperson]

SQ Bimmer: When you do the bleeding with the slave cylinder rod, try doing it with the pressure bleeder on, and see if that does it.

tried that

SQ Bimmer: Also, maybe try pumping the clutch pedal 10 times with the pressure bleeder on.

tried that too

Hm I reinstalled my old clutch, but I had everything apart... The thing is, when i put the slave in the bellhousing its REALLY easy to put back in. Like normally there was a bit of resistance Id have to hold the slave down with my other hand to get the nuts to go on, now i can kinda push it in there with very little effort. Which makes me think that there is air in there...

[SQ Bimmer]

Yea, it should be a PITA to get that slave cylinder put back in. Being easy would indicate an air pocket.

Here's what I would do then, and it involves a rubber mallet... Put the pressure bleeder on, pump it up, open the bleed valve on the slave cylinder, and BANG THE SHIT out of the master cylinder to loosen up any possible air pockets. Give it a good couple hits, then jump under the car REAL quick and see if any air comes out. If air does come out, give it a bunch more good whacks and see what happens...

[bmwperson]

here is another thing, every time i let the pressure out of the pressure bleeder air bubbles come out, even if i just move the slave rod air comes out the pressure bleeders hose is that normal?

oh and after u bent your friction disk was it easier to put the slave in then usually?

[SQ Bimmer]

As long as there is always fluid in the BOTTOM of the fluid reservoir, no air will go in there, regardless of what your pressure bleeder does.

After I bent my clutch disk, the slave cylinder was just as hard to put in as it is with a non-bent clutch disk. Like you said before, that is a symptom of an air pocket...

Also, I hate to suggest it mainly because we are so dependent on our pressure bleeders, but get a friend and do a manual bleed via clutch pedal, and see if that fixes it...

Also, I'm sure you checked this already, but make sure your fluid line to your slave cylinder is tight.

[bmwperson]

no air bubbles came out after hitting it with a rubber mallet...

[SQ Bimmer]

Alright then... grab a friend and bleed that thing manually. Make sure you top off the fluid reservoir before you start so it doesn't run dry.

[TXBDan]

whenever i flush my brake/clutch fluid w/ my power bleeder, i can never get the clutch slave to bleed w/ just power bleeder. it always takes somebody pumping and lifting the clutch pedal by hand to do it.

for what thats worth