slow loss of clutch hydro pressure when in heavy traffic

[211]

2k OBW.
Admittedly the 'ol soob has been sitting for a few months while i've been commuting on my moto.
Today I needed to drive it to work (30mi highway commute) and got caught in traffic. Near standstill traffic for almost 5 miles. I noticed about midway through the jam my clutch began to feel like it was loosing pressure. The freeplay would progressively get further and further towards the floor and the clutch would grab really early on upon release. It got scary... to the point I stopped using the clutch unless I had to, shifting only when engine/trans speeds were matched.
 

When I got off the freeway and made the straight shot to work I felt the clutch starting to build pressure again. Got to work, looked under the hood; no leaks, resivour is full and fluid is clean. I put in a new clutch about 60k miles ago and everything always ran spot-on with this car. Never any issues till today.

Any ideas what may cause this?

Again, its' a hydro/pressure thing, not a clutch disk wear thing. I know how different the two issues feel.

thanks

[idosubaru]

the slave cylinder and hoses on those are known to fail and often replaced as a set. i'd probably think they need replaced but would be nice to hear more verification since that's the only parts of those systems i've worked on.

 

be prepared for a really annoying bleeding process. pump all you want those jokers don't like to bleed.  bleed a little while you can ride your moto and let the thing sit overnight for air bubbles to move up, then bleed again. i think GD has a repeatable process, which any shop does since they need to turn cars quicker. 

[nickb21]

Definitely time for a new slave + hose. I would wager that once it starts warming up, the problem will get a lot worse (at least that's what happened to me). Summer heat + traffic was real bad news.

 

I never really had any issues bleeding the slave, not sure what all the fuss is about. I made it easier on myself the 2nd time around and stuck a speed-bleeder on it.

 

Top off reservoir. Hose on bleed nipple. Open bleeder, push and hold clutch to floor, close bleeder. Repeat.

Edited August 1, 2013 by nickb21

[211]

 

the slave cylinder and hoses on those are known to fail and often replaced as a set. i'd probably think they need replaced but would be nice to hear more verification since that's the only parts of those systems i've worked on.

 

be prepared for a really annoying bleeding process. pump all you want those jokers don't like to bleed.  bleed a little while you can ride your moto and let the thing sit overnight for air bubbles to move up, then bleed again. i think GD has a repeatable process, which any shop does since they need to turn cars quicker. 

Thanks, and I figured as much. Its a pretty simple system. Resivoir, hard line, rubber hose, slave cylinder. The way I imagine it... for a gradual loss of pressure I'd expect to see leakage, its a sealed system so if you're loosing pressure that's gotta mean its exiting someplace.. or the hose is ballooning

[Fairtax4me]

Pull back the boot on the slave cylinder and see if there is fluid inside it.

You could also just have old fluid that was starting to boil while sitting in traffic in the heat. It's just brake fluid which absorbs water as it gets old, and that degrades the fluid and lowers its boiling point.

 

I've always had good luck removing slave cylinders and pumping them by hand to remove air. Open the bleeder (if it has it) and allow the cylinder to fill with fluid via gravity feed or by pumping the pedal once or twice. Close the bleeder, turn the cylinder so the hose is at the top and squeeze until it bottoms out. This forces all of the fluid (and air) back into the line and up and out of the reservoir. Wait a few seconds for any air to rise out of the fluid. Repeat two or three times waiting for a few seconds between steps for air to rise to the top.

[pearlm30]

I am thinking install a speed bleeder on it as well. Do you have the part number handy?

Thanks

 

 

 

 

Definitely time for a new slave + hose. I would wager that once it starts warming up, the problem will get a lot worse (at least that's what happened to me). Summer heat + traffic was real bad news.

 

I never really had any issues bleeding the slave, not sure what all the fuss is about. I made it easier on myself the 2nd time around and stuck a speed-bleeder on it.

 

Top off reservoir. Hose on bleed nipple. Open bleeder, push and hold clutch to floor, close bleeder. Repeat.

[nickb21]

Hmm. You know, I just saw the box with the extra 1 in it the other day. No idea where I put it though. I believe I used the same part that goes on the front calipers. (Googled some other posts + their site to get that part number). If I run into it I'll post it.

 

Edit: Hah!
 

http://www.ultimatesubaru.org/forum/topic/59010-bleeding-clutch-speed-bleeders/

 

I ordered mine from a local 'performance' parts store, was the same price as getting it through the speed bleeder site and easier for me to deal with.

Edited August 2, 2013 by nickb21