Clutch pedal gets stuck all the way down

[zalez05]

I was reversing out of my driveway and the clutch pedal got stuck all the way down to the floor...The car would not go into gear and I had to push it...After about 15 min I started to check where the pedal goes up to the master cylinder and all of a sudden the pedal popped back up....Which is super weird to me...Do you guys think i could have triggered something....I checked the brake fluid reservior and it is full..

Does the brake fluid reservoir and the clucth hydraulic system use the same reservoir?? Cause im thinking it they use the same on and my slave cylinder was bad then wouldnt I be low on fluid all the time?? Its not the case my reservoir is full.....So i guess my questions is could either cylinder go bad without leaking??? And why just simply sticking my hand behind the pedal to where the master is engage the pedal again??

Does this sound like air in the system, or a bad throw out bearing??

[e34briliant]

I had the same problem on a E34 a few years ago. I filled up the brake fluid reservoir (yes, its the same as for the clutch hydral system) while pumping the clutch pedal. Then I could drive the car a few days before having to do it again.
After a few weeks I left the car at a workshop and they had to change the slave cylinder I think it was...

The brake fluid reservoir level will sink as you pump the pedal (if I remember correctly). So just try to pump the pedal and see if the level sinks, then add more hydral fluid and pump some more...But I think this is only a temporary solution...

[BennyM]

When my clutch cylinder went, it was the same deal. No leaks, just pedal stuck to the floor. I replaced both slave and master to be safe. The master, I believe, is a more likely culprit. It's also a far bigger PITA to replace.

[zalez05]

Thanks BennyM and e34briliant I really appreciate your help!!!...Im going to look into changing the slave, then the master...........

[genphreak]

And no, they don't share the same circuit/fluid- that'd be dangerous (let alone work reliably, nad the brakes need to be exactly that :).

[e34briliant]

Steering fluid and clutch hydralics is the same! :)

[zalez05]

genphreak, I have been told by a few forums that they use the same reservoir....There is no such thing as hydraulic clutch fluid, its just brake fluid, dot 4.......Well I may be wrong so if they do use different reservoirs where are they...I can find the brake fluid reservoir, where is the clutch fluid reservoir??

[Ross]

It's almost certainly the clutch master cyl. Nothing about a slave failure that would have the pedal stay down. A broken pressure plate could also do this but is unlikely.
Some models draw fluid for the clutch from the brake resevoir. The tapping point is higher for the clutch so leaking clutch hydraulics cannot deplete the brake fluid.

[zalez05]

Thanks everyone for your helpful responses...Ross, is the fact that the pedal came back up and its been working now a good indicator that its the master?? If it were the slave that failed then what would be some of the indicators??

Thanks again!!

[Ross]

A failed slave just leaks. Watch your fluid level.

[genphreak]

Not in either of my manual e34s or e28 or e24 do they 'share fluid'... and as I said, it'd be real stupid to make either system depend on the other. I'm no mechanic, but I've never this be done, imagine if a leak in the clutch cylinder caused your brakes to fail. Courts would award damages against a manufacturer way too fast for anyone to think about saving money that way...

[BennyM]

Genphreak - If this is true, then there should be two DOT4 fluid reservoirs under the hood. I'd be curious to see a picture of them sitting side by side 'cause maybe they have different design requirements in Australia compared to the US. When I redid my clutch hydraulics, I drained the brake fluid reservoir, and waddia know, the clutch line was empty then too. And when I filled the brake fluid reservoir again, the clutch system had plenty of fluid (and air bubles) to bleed too. Brakes and clutch sip from the same bottle, but they are on separate circuits.

[whiskychaser]

Genphreak - If this is true, then there should be two DOT4 fluid reservoirs under the hood. I'd be curious to see a picture of them sitting side by side 'cause maybe they have different design requirements in Australia compared to the US.
Think you will find on RHD cars the clutch does indeed have its own reservoir. It sits just in front of the E-box;) And look - a steering reservoir with a green ring on the lid!! (ref another thread)

[zalez05]

The post was for my 1990 525i not sure what an RHD car or austrailian bmw's.....BennyM you are right...In my 1990 525i which is in United States California, the brake fluid and clutch uses the same reservoir....There is only one dot 4 reservoir, in my car...Now other cars im sure there probably could be more than one...

Thanks for your help guys Im learning a ton and hope to contribute more to the forum once Im a bit more educated...