e9 clutch issues

[skk]

Engine turning is unrelated to clutch hydraulics (only brakes, vacuum boost). You mentioned new master, slave in 1990. They are now 34 years old.
Have you been refreshing the hydraulic fluid every 24 months all these years? If not, its normal, cheap insurance, and relatively easy to refresh master, slave, and hose.
If there's something wrong inside the bell housing, you'll be dropping the transmission, but start with the easy stuff.
Also, 34 year old flex lines to the brakes are way past their expiration date.

 

[taylorcom]

Engine turning is unrelated to clutch hydraulics (only brakes, vacuum boost). You mentioned new master, slave in 1990. They are now 34 years old.
Have you been refreshing the hydraulic fluid every 24 months all these years? If not, its normal, cheap insurance, and relatively easy to refresh master, slave, and hose.
If there's something wrong inside the bell housing, you'll be dropping the transmission, but start with the easy stuff.
Also, 34 year old flex lines to the brakes are way past their expiration date.

I was wondering if engine being on would make a difference. When the clutched failed to disengage 6 days ago, the gear shift became very hard to move, even -- if I recall correctly -- with the engine off. Now, with engine off, the shifter moves easily between gears.

Yes, 34 years is a long time, but mileage is low. The clutch master cylinder is older than that. No, I haven't changed the fluid in that time. Brake hoses seem fine.

 

[Ohmess]

I was wondering if engine being on would make a difference. When the clutched failed to disengage 6 days ago, the gear shift became very hard to move, even -- if I recall correctly -- with the engine off. Now, with engine off, the shifter moves easily between gears.

Yes, 34 years is a long time, but mileage is low. The clutch master cylinder is older than that. No, I haven't changed the fluid in that time. Brake hoses seem fine.

Taylor - I think what several of us are trying to communicate to you is that seals and other rubber parts deteriorate over time and need to be replaced before they fail. It sounds like this is what is happening with your clutch slave cylinder.

As to brake hoses, you need to replace yours. Do not go with "brake hoses seem fine." In addition to the potential for the hoses to fail under stress, when your brake hoses deteriorate, they release very small fragments inside the system. These fragments can and do migrate around. I had these little fragments migrate into the brake proportioning valve, clogging it. This both prevented fluid pressure from getting to the rear calipers (i.e., no rear brakes) and required a replacement of the brake proportioning valve.

 

[taylorcom]

Taylor - I think what several of us are trying to communicate to you is that seals and other rubber parts deteriorate over time and need to be replaced before they fail. It sounds like this is what is happening with your clutch slave cylinder.

As to brake hoses, you need to replace yours. Do not go with "brake hoses seem fine." In addition to the potential for the hoses to fail under stress, when your brake hoses deteriorate, they release very small fragments inside the system. These fragments can and do migrate around. I had these little fragments migrate into the brake proportioning valve, clogging it. This both prevented fluid pressure from getting to the rear calipers (i.e., no rear brakes) and required a replacement of the brake proportioning valve.

Yes, I do replace the brake hoses. But the issue today is the clutch malfunction. And my question is: Is the immediate issue in the cylinders, the hose, or the clutch itself?

 

[Stevehose]

Same principle regarding @Ohmess advice - hydraulic fluid eats the hose for both brakes and clutch components over time.

So we’re recommending to replace or rebuild the slave and clutch master cylinders and get a new line between them. It’s past time and more than likely your issue.

Often times if you only replace 1 then it causes one or both of the other to fail soon after.

 

[dang]

The clutch assembly itself is all mechanical and rarely do you get an issue that gets worse as you use it then works fine again later. Hydraulics can be very unpredictable because of seals, oils, etc. You could just replace the master and slave knowing that it may not fix the problem and still feel good about replacing them anyway. But it will probably fix the issue.

 

[stphers]

Brake fluid by nature is hydroscopic which means it absorbs moisture which in turn weakens the viscosity of the brake fluid and because moisture is introduced into the system slowly over time , that moisture can cause rusting inside the cast iron cylinders This causes the seals to " stick " on the inside wall and can and probably has ripped the edge of the seal causing the fluid to bypass within the cylinder THIS is why the brake fluid is recommended to change every 2 years REGARDLESS of mileage. If you are not doing this, you are neglecting your vehicle. Please don't give your self a pat on the back for not changing the fluid in years

Thanks, Rick

 

[taylorcom]

Brake fluid by nature is hydroscopic which means it absorbs moisture which in turn weakens the viscosity of the brake fluid and because moisture is introduced into the system slowly over time , that moisture can cause rusting inside the cast iron cylinders This causes the seals to " stick " on the inside wall and can and probably has ripped the edge of the seal causing the fluid to bypass within the cylinder THIS is why the brake fluid is recommended to change every 2 years REGARDLESS of mileage. If you are not doing this, you are neglecting your vehicle. Please don't give your self a pat on the back for not changing the fluid in years

Thanks, Rick

Satan himself has insisted I mention that the slave, if that is the problem, has lasted 34 years.

 

[bill]

Bill, Good idea to replace the line. I searched on eBay and found this, which the seller claims fits the '72 3.0 CS, but it appears to have a male end and a female end: https://www.ebay.com/itm/283995769979?fits=Year:1972|Model:3.0CS|Make:BMW&itmmeta=01J3ZGDYAPNY8S5MGM00Z1Y9AJ&hash=item421f778c7b:g:nzgAAOSw3-BgeKLF&itmprp=enc:AQAJAAAA8L3CD7+yupFhBxRjZtQQRUSWagRltaQGshKlh5CYvG94uKs8le97bpl1fLumASEvwXPEpUW3YPOUBYxrz4cjWc0+FogL0C/U/udulsusZfa6XBtnMEL0UuHZJIfxaGtkIebMfuQETjYmT/QhtZ1T0/gEjYpIoXZZFZLIt9/VsbELzk8mCzsKgEnxUQIBuFELLhRCxRCUVxgXyRuzTeqiJC/cs7YYmm2ZV28H94IthPaf3DFvnlB4O2ZjPrNbHpJXlZqZ5qo9DLwihaqqtF7gmLJ+L/dY5fZM2B2Gcgn3LxTWhpx1gFho6Z6wzxG3WJJH1Q==|tkp:BFBMvOW38J9k

Meanwhile, W&N has one with, as you said, two male ends: https://www.ebay.com/itm/283995769979?fits=Year:1972|Model:3.0CS|Make:BMW&itmmeta=01J3ZGDYAPNY8S5MGM00Z1Y9AJ&hash=item421f778c7b:g:nzgAAOSw3-BgeKLF&itmprp=enc:AQAJAAAA8L3CD7+yupFhBxRjZtQQRUSWagRltaQGshKlh5CYvG94uKs8le97bpl1fLumASEvwXPEpUW3YPOUBYxrz4cjWc0+FogL0C/U/udulsusZfa6XBtnMEL0UuHZJIfxaGtkIebMfuQETjYmT/QhtZ1T0/gEjYpIoXZZFZLIt9/VsbELzk8mCzsKgEnxUQIBuFELLhRCxRCUVxgXyRuzTeqiJC/cs7YYmm2ZV28H94IthPaf3DFvnlB4O2ZjPrNbHpJXlZqZ5qo9DLwihaqqtF7gmLJ+L/dY5fZM2B2Gcgn3LxTWhpx1gFho6Z6wzxG3WJJH1Q==|tkp:BFBMvOW38J9k

Carl Nelson, bimmerdoc.com has what you need (probably.) I just ordered one recently…and his price is the best by far.

 

[taylorcom]

The plot thickens. Today I received this advice from my brother, retired owner of Taylor Co., an independent BMW repair shop in Claremont, CA. The other e9 Bruce mentions is a '71 2800 CS:

"As to the clutch, have you observed the slave cylinder operation after the incident when you couldn’t disengage? With no leaks it sounds like it may be mechanical in the clutch housing. Not the pressure plate springs though, because their failure would mean no clutch engagement. But perhaps the release bearing, the fork or the shaft the release bearing rides on is creating the problem. Years ago I had an issue with dad’s CS. The front transmission seal was leaking trans fluid onto the clutch disc, as the oil got worked into the disc it became sticky and even though the mechanical and hydraulic parts were operating correctly the disc was stuck to the flywheel and would not disengage. So use your mirror to confirm the slave is operating the fork and go from there."

I may try to (safely) reproduce the clutch failure, then take a quick look at the slave again.