So I'm in the process of putting in a new clutch. I finally got the new clutch in and transmission bolted back on tonight. I hooked up the slave cylinder to make sure the new clutch was working alright before I went any further.

When I tried the clutch pedal, it just went to the floor and didn't come back up. Turns out that I somehow air in the clutch hydraulic system, and now I need to bleed the slave cylinder. I did a little research online....and it seems like this is pretty common when you change your clutch for some reason. I'll bleed it tomorrow...and I should be good to go.

My question is......how in the hell does air get in the clutch hydraulic system if you don't crack the bleeder or take off a line? If it's been all sealed up for 13 years, why all of a sudden would air get in the system? All you really do when you take the transmission off is unblolt the slave cylinder from the mount on the transmission, and move it out of the way.....you don't open up the hydraulic system and expose it to air at all.....how does air get in the clutch system if you don't open it up??? Just trying to make sense of this........

 

My guess is that it's what Nik alluded to in the other thread, not so much air in the system, but total failure and you'll need a new one.

Best guess is that after a certain amount of time and heat the seal inside the unit form fits exactly, works fine as long as you don't disturb it out of it's natural movement, but any variation of that movement, angle on the shaft, or extension from not being held in place by the clutch arm, then breaks the prefect seal that it did have.

This is my only thought since new ones seem to not be near as touchy.

 

But if air was getting in through a bad seal.....wouldn't fluid be getting out? The slave cylinder isn't leaking anywhere...so I'm just wondering where the air got in at.

Doesn't really make much sense.

 

I haven't had to replace the clutch or slave cylinder on my Mini yet, I had a BMW530i in which I had to do a new clutch; after I did the clutch and drove it a bit, the peddle would go to the floor. Friend of mine who was a BMW mechanic explained to me that when you change the clutch, the piston from the slave cylinder has less travel because of the new thickness on the clutch plate. The seal on the piston is now seated in a new position which allows air to be sucked in. That made sense to me, changed the slave cylinder, problem solved. This could be the case here...

 

Yes, that makes good sense.

 

Yea, its creeped air into the system when the plunger on the slave cylinder moved when unbolted. Thats my guess.

 

I will try bleeding it first....if that doesn't work, I guess I will replace the slave.

 

We bleed every slave prior to reinstallation due to this problem, some need it others don't, but the less you have to remove and install it the lesser your chances of killing it.

If you don't have the special slave bleed tool you need to be extremely careful when compressing the cylinder, if you **** it in the bore while compressing it you run a very high chance of destroying your slave, even if it's new out of the box.

When we are installing them I always pull the boot back off the end of the plunger so you know if there is fluid leaking past the seal, if there is any fluid in that boot replace the slave.

We've got the slaves on hand if you end up needing it, (though I think I already said that)

Slave Cylinder

 

Well, I got all of the air bled out....and not it's working like it's supposed to.

Thanks for the help! Should have the car back on the road later today to test out that new Valeo cltuch.

Such a soft pedal.....it's going to take some getting used to.

 

It took me all of a day to get used to it. I wouldn't go back.