Clutch Master & Slave Help Needed

[srider]

Hi, First post here and appreciate your help.

I'm a new E30 owner. Clutch slowly developed the following problem: It wouldn't go into any gear while running. With the engine off, I could run through all the gears, so unlikely it's linkage. If I start the car while it's in gear, with the clutch still in the car rolls slightly, so the clutch is not fully disengaging.

I bled the system and it resumed normal function for around 30 minutes of driving, then the same problem returned. Some previous posts here suggested the slave cylinder as the culprit so I replaced that, re-bled the system, and same thing happened: shifted fine for around 30 minutes and now doesn't.

Could the master cylinder be the cause of this? There is no fluid on the interior carpet.

If not the master cylinder, what else could be causing air to get into the system?

Thanks in advance!

[tomstin]

A few thoughts, as old as these cars are now it's probably a good idea to replace both the slave, master and flexible hose at the same time. Junk in the system could destroy the newer parts if replaced separately. And as much of a pain as it is to get the system bled, do it once and be done.

Could you have a clutch going bad? Oil from the engine rear main or front seal of the transmission could be swelling the clutch disk?

[82eye]

when was the last time it had a new disc and pressure plate? pivot pin could be worn to the point it is part of the issue as well.

[srider]

Thanks for your replies. I don't know the age of the disc, pressure plate or pivot pin unfortunately. I'm (perhaps erroneously) operating under the assumption that those 3 are good only because after the system is bled, it shifts like butter for awhile (~30 minutes). In my imagination, ~30 minutes is the amount of time it takes for air to get back into the system somehow. Sound reasonable?

I hadn't considered the flexible hose but will look at replacing that with the master cylinder next, possibly this weekend.

Regarding bleeding the system, it seems like every E30 owner has a slightly different method (pressurized or not, pumping pedal or not, etc, etc) Anyone have a reliable and relatively fool proof method they're willing to share?

Thanks again

[reelizmpro]

I would first check to see if the clutch pedal is traveling far enough. I had a similar problem where it was very hard to shift. Turned out my aftermarket adjustable clutch pedal stop had loosened over the years and was stopping the pedal prematurely. So first check for anything obstructing the clutch pedal travel. Have you noticed any fluid loss? there's a plastic elbow on top of the clutch master cylinder that gets brittle and can leak/break. I had a shop replace my clutch master once and they reinstalled that elbow backwards which caused it to leak a few months later. When that elbow leaks, it drips into the carpet and soaks into the padding behind it. Finally, Invest in a Motive pressure bleeder with the euro adapter for our cars. It makes bleeding everything a one man operation and so much faster/easier.

[srider]

I just got home and went out and looked at it.

No fluid that I can feel in or behind the carpet near the clutch pedal.

With the car off and hadn't been driven in 24 hours, the clutch pedal was at rest around 75% of it's travel to the floor. I could manually pull it back into its normal unused position.



reelizmpro thanks for the endorsement of Motive I will look into it. Originally I was considering this: how to bleed stubborn BMW clutch hydraulics - YouTube

[reelizmpro]

I also found that a shop installed a cheap off brand clutch master cylinder that failed after I got home. Pedal to the floor and would not return. I bled the system about 3-4x. Finally, I caved in a got an FTE clutch master and it solved the problem. It's unbelievable how such low quality parts are being sold at big chain parts suppliers. If your clutch master is due for replacement, go ahead and change it. They recommend you change the line and the slave cylinder at the same time.

[TobyB]

I agree with your logic- if bleeding it makes it better, then it's the hydraulics.

And yes, air can get pulled past a worn main cylinder seal. It may seal fine with pressure
against it, but once there's no pressure, the cup might be allowing air to slowly leak
into the cylinder.

I'd swap it. Or maybe rebuild it, if kits are still available and the good cylinders
are as expensive as they have been in the last half- dozen years...

t