Weird e92 M3 6MT issue encountered today

[akraus92]

Some things to explain the car...
2008 e92 M3 6MT with 56k miles

I was sitting in the driveway this morning and was in a bit of a rush, so I hopped in my car and started it up with the clutch depressed, after about 5-10 seconds with the clutch still depressed I put the car into reverse and suddenly the clutch pedal went limp (very little to no force pushing back on my foot) and the car started to progress backwards. My foot never left left the clutch and was depressed since I started the car. My foot was still slightly pressing the brake as I was getting ready to move over to the gas to start backing up. The only way that I can describe this was it was as if someone unhooked my clutch cable in that instant and eased it out, this was by no means a rough instant (clutch cable did not snap or anything) it just eased off of it until it was completely engaged as my foot had the clutch pedal pushed all of the way down. Since it was clear the clutch was not working I pressed the brake harder to stall my car and when I restarted it the problem was gone and it drove like normal for the rest of my commute.

If anyone has experienced this or have heard of this happening/knows why it happened please let me know. Thanks

[tony093]

bleed the clutch when you get a chance.
It sounds like you air in the system.

[DSilk]

Originally Posted by tony093

bleed the clutch when you get a chance.
It sounds like you air in the system.

Either that or the slave cylinder is leaking.

[dparm]

Agreed, visually inspect and make sure you have no leaks, then change the fluid and bleed the system.

[akraus92]

Thank you all I will look into it.

[nitrojunky]

Originally Posted by DSilk

Either that or the slave cylinder is leaking.

this. master or slave cylinder leaking. may not be leaking out of the cylinder either, could be leaking past the master's seals and back into the reservoir.

[Mvy]

When my clutch wore out the same sort of thing happened to me. You might need a new clutch. With that mileage and age, its about time. Get prepared as you will also need to replace the flywheel as they no longer make the 2008 version.

[hlmiii]

Originally Posted by nitrojunky

this. master or slave cylinder leaking. may not be leaking out of the cylinder either, could be leaking past the master's seals and back into the reservoir.

This is the most likely, by a fairly good margin. And cheaper and simpler than other possible issues (clutch, linkage, etc.)

Clutch is pretty young and shouldn't need replacing so soon, unless it's had a lot of wear/abuse with stop/start/launch history. I've had BMW clutches in all M generations go twice as far as yours.

When you are driving in the car now, be very aware of any actions/responsiveness/"feel" for shifting, engagement, etc. This is for your safety as well as diagnosis.

[bkdore]

I had this happen once - about a week after changing brake fluid with a power bleeder. It worked fine for a few days and then did almost exactly the same thing to me. I checked everything, didn't find anything obviously wrong and when I tried again it worked normal. It's worked fine since, although I started it in neutral for several weeks after out of caution. I wrote it off to getting a bubble of air somewhere it wasn't supposed to be.