Clutch pedal to floor - clutch not disengaging

[toddman35]

Went to start up my car the other day and the pedal went to the floor and the clutch didn't disengage. The pedal stays on the floor unless I pull it back up. Pumping it doesn't build any pressure. I didn't notice any leaks from the underside of the car.

Master cylinder? Slave cylinder?


Clutch is a clutchnet 6 puck with a red pressure plate replaced ~5k ago. I believe I also replaced the slave with a new 325i one at the same time, but it may have been used (3-4 years ago now). Has run fine up until this.

Ideas on where to start with this? I'll probably be towing it to the shop this evening so I can have a look under it then.

[pbonsalb]

Typically the slave, but could be the master.

[weaksauce]

start with teh slave. its cheap and easy.
then go to the master if it won't bleed out.

do you have a clutch stop? if not, you might have overextended the master and blown ou the seals in it if you stomped the clutch pedal really hard.

if its the master, you can get under teh dash and see it leaking. most of the time it will leak onto the carpet in the floor board.

[toddman35]

Just pulled the slave, the piston wobbles around a bit but its still there and there aren't any leaks coming from it. From what I remember the wobbling is pretty normal?

I felt the carpet under the dash and it still seems dry as well. Whats my move now other than to investigate for leaks around the MC?

I spent some time looking under the dash and didn't see any leaks. Brakes work fine, fluid level is where it should be also. No noticeable leaks under the reservoir under the hood either.

[MThrizze]

the pedal recently fell to the ground on my roomates e46 M and it was the master, regardless it is a hydraulic issue, honestly both cylinders are quite inexpensive I would do both plus some clutch pedal bushings and call that a day.

[Albertan]

It is possible that the pivot pin has broken. That would allow the slave to extend but not disengage the clutch.

[toddman35]

the pedal recently fell to the ground on my roomates e46 M and it was the master, regardless it is a hydraulic issue, honestly both cylinders are quite inexpensive I would do both plus some clutch pedal bushings and call that a day.

I'd typically agree, but I'd rather not replace the slave for the heck of it when its only got 6k on it.


It is possible that the pivot pin has broken. That would allow the slave to extend but not disengage the clutch.

I hope not, wouldn't that allow the slave's piston to over extend?

[pbonsalb]

Stick your finger in the hole. Is the fork still firm on the throwout bearing and pivot pin? If so, either the slave is not bled properly or the master has failed. The master is not much more expensive than the slave, but in an awkward position under the dash behind the pedals. You can do it.

[toddman35]

I'll check out the fork. I bled the slave when I replaced it 6k ago and its worked great until now so I doubt that air is my problem. I'll report back. Anything in particular I should know when replacing the master?

The fork moves back and forth ~3/4" when I pull on it and it feels like its pivoting. The pin is on the passenger side correct? I don't have any vertical movement when pushing up or down on the fork. Sound normal?

[95s52]

Had the clutch left laying on the floor problem and it turned out to be the throw out bearing.

[toddman35]

Bump, anyone know if the fork operation sounds normal?

[weaksauce]

yes, in and out a little is normal.

[jonb94118]

I'm having a similar problem - although in my case the clutch pedal does return and the pedal is firm. I replaced the slave with a spare just in case and bled it pretty well and still my clutch will not disengage. Just put in a new clutch, pp and throwout bearing a few months ago as well. In my case, it seems the clutch disc is actually stuck to the flywheel, the clutch fork is bent or the pivot pin is cracked. The fork seems to be in the all the way extended position and with a 2 foot long extension, I was not able to move the clutch fork at all - telling me that something is stuck in there. This happened during a track event where when having no problem shifting from 3-4, on the upcoming turn when I went to downshift to 3, it would not go into any gear. No money shift, just wouldn't go into gear. Was working perfectly prior to that for 2 events. I have it at my friends shop right now and will be taking the trans out today or tomorrow to see what's up. I'll update when I know more.

In your case, if you get no pedal return and the pedal is soft, it has to be hydraulic as others have stated - master, slave or air. With the slave out, pushing the slave pin in by hand should require a good amount of force - think of the force required to press the clutch fork/overcome the pressure plate springs. If it's pretty soft, it will not be able to push in the fork. If you have a pressure bleeder, you might also be able to attach it and pump it up to about 15 psi to check for a leak. leave it attached and see if it bleeds down on its own. Frustrating problem I know.

[toddman35]

I'm having a similar problem - although in my case the clutch pedal does return and the pedal is firm. I replaced the slave with a spare just in case and bled it pretty well and still my clutch will not disengage. Just put in a new clutch, pp and throwout bearing a few months ago as well. In my case, it seems the clutch disc is actually stuck to the flywheel, the clutch fork is bent or the pivot pin is cracked. The fork seems to be in the all the way extended position and with a 2 foot long extension, I was not able to move the clutch fork at all - telling me that something is stuck in there. This happened during a track event where when having no problem shifting from 3-4, on the upcoming turn when I went to downshift to 3, it would not go into any gear. No money shift, just wouldn't go into gear. Was working perfectly prior to that for 2 events. I have it at my friends shop right now and will be taking the trans out today or tomorrow to see what's up. I'll update when I know more.

In your case, if you get no pedal return and the pedal is soft, it has to be hydraulic as others have stated - master, slave or air. With the slave out, pushing the slave pin in by hand should require a good amount of force - think of the force required to press the clutch fork/overcome the pressure plate springs. If it's pretty soft, it will not be able to push in the fork. If you have a pressure bleeder, you might also be able to attach it and pump it up to about 15 psi to check for a leak. leave it attached and see if it bleeds down on its own. Frustrating problem I know.

I've heard of the clutch disk fusing to the flywheel during rough drag launches, but never something like that happening with the stock disk?

It turned out to be the master cylinder though:

http://img.photobucket.com/albums/v229/toddman36/8b695f77.jpg

Which explains why I didn't have any fluid leaking. Replaced it and we're back in action. :D

[weaksauce]

nice!

[Uliman]

I've heard of the clutch disk fusing to the flywheel during rough drag launches, but never something like that happening with the stock disk?

It turned out to be the master cylinder though:

http://img.photobucket.com/albums/v229/toddman36/8b695f77.jpg

Which explains why I didn't have any fluid leaking. Replaced it and we're back in action. :D

This just happened to me a couple of days ago on my 99 M3 with 127k miles on it. I simply cannot believe that this piece that broke is made out of plastic. My mechanic said it was a royal pain in the ass to change and all the Jap cars he has worked on have this particular part of the master cylinder made out of metal. He told me that BMW does not even offer an upgraded part with a metal end. On the other hand, it did last 127k miles so that means something anyways.

[NoLastName]

I wonder if worn clutch pedal bushings contribute this type of breakage? The eyelet is designed for rotational movement and compressive force, but if the clutch pedal arm is flopping around the eyelet will see side loads too. Just a thought.

[dano670]

I wonder if worn clutch pedal bushings contribute this type of breakage? The eyelet is designed for rotational movement and compressive force, but if the clutch pedal arm is flopping around the eyelet will see side loads too. Just a thought.

I wouldn't be surprised. I had my master cylinder go out and it turned out that when i replaced it, 1 of the bushings were cracked. I replaced them both with delrin ones but the peddle still isn't sturdy. You can feel that plastic loop shift when you push in the pedal.

I used the later model master cylinder and I am not sure that tip is plastic anymore.

[Uliman]

I wonder if worn clutch pedal bushings contribute this type of breakage? The eyelet is designed for rotational movement and compressive force, but if the clutch pedal arm is flopping around the eyelet will see side loads too. Just a thought.


Good point! I'm going to check this out over the weekend. Never even thought about this possibility. It totally sucked when this happened; absolutely rendered the car inoperable. Good thing it happened in a parking lot just as I was cruising into a slot. And thank goodness for AAA and the tow to my mechanic. He definitely did not like this job, however, complaining of side body aches from the positions he had to place himself in to do this. Guess I'll have to buy him some hooch (he is from the Czech - the highest beer consumption nation in the world!!)