THSCC Forums

Ok, so i'm bleeding my brakes and clutch today as usual using the motive power bleeder. bleed the brakes fine. go to the clutch slave. its bleeding along fine and then all of the sudden THRRSTSTSTSTS all this air shoots out. i'm like damn wtf.

I go check the reservoir, its full to the top. there is still fluid in the bleeder. but the pressure has dropped a lot.

clutch pedal is dead and just flops to the floor.

So then i have my gf come out and pump up/down, hold. i release, close, up/down/hold, i release, close. it gets a little better and the pedal starts to come back. then i continue and THRESSDSDFDS. more air shoots out. we repeat a bit but nothing but air comes out. fluid levels are still ok. i can't get anything out of the slave anymore but air.

I checked the master cyl. no visible leaks and its only about 25k old. i can open the bleeder valve w/ a full reservoir and nothing comes out. If i add pressure from the pressure bleeder, just air shoots out. pedal is dead.

Any ideas?

My guess is that the seal on the piston in the master cylinder has failed. Time for a kit or master cylinder.

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George Bright Member # 141
One of the youngest of the old farts.
Yes I voted against you joining the club.

Which car? My E36 has a separation in the reservoir that doesn't let fluid get to the clutch side very well. I have to keep the reservoir topped off when I do the clutch.

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Colin O'Connell

'94 BMW NASA SPEC 3
'02 F350 tow vehicle (not bad for a tow vehicle)
'97 Miata STO (autoX and sunny day spoils vehicle)
'97 BMW 328i (loaner to the kids when their cars don't work vehicle)
'05 Toyota Highlander

I had a terrible time bleeding the clutch on my RS last week and discovered that the master cylinder was never fully retracting. Apparently the PO tried to adjust the pedal free play using the clevis under the dash and ended up blocking off the flow from the reservoir into the master cylinder by doing that.

From your description it does sound like the slave seal might be dead but possibly the power bleeder is just overcoming it - the seal isn't made to work against a vacuum.

--Kevin H.

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2003 WRX (again!)

Just use the starter to get going and float the gears. It worked fine this weekend in The Dog.

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Rubbin' is Racin'

Dan - I had the same problem with an E36 as you're describing. I think it's a combination of the location of the fluid feed at the very top of the master cylinder / reservoir (if the fluid level drops slightly below completely full with the bleed screw open, air quickly rushes into the line) and the entire column of fluid running vertical - the fluid drains out at the bleed screw so quickly it may cause air to get sucked in from the bottom of the column (at the slave cylinder bleed screw) due to path of least resistance as the fluid is escaping. After almost missing a track event from this, I learned the hard way just to stick with the old 2-person operation 'up/down pedal w/open/close bleed valve' method for the clutch fluid. And you don't need to bleed the clutch line nearly as often as the brake lines - clutch usage doesn't result in much, if any, mixing of the fluid from the clutch line into and from the master cylinder / reservoir - the fluid in the clutch line almost entirely flows back and forth between the clutch pedal cylinder and the slave cylinder, not to/from the brake master cylinder / reservoir.

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Keith Q.
2008 Top Gun
http://www.youtube.com/watch?v=KmX8XuZ_DCo&NR=1

^that could be right on.

I finally filled it up to the very very top and just kept going at it manually. Finally the pedal came back and all is good in the universe.

Thanks!