Clutch problems
I would like to ask your advice regarding problems I have with the clutch on my 1991 Saab 9000 2.3T manual with 220,000 miles. I decided to replace the clutch pressure plate, friction plate and release bearing on the car, together with the slave cylinder. All parts were new Borg & Beck items bought on ebay. After many hours of work, I was pleased with the smooth operation of the new clutch, with no slipping in fourth or fifth gears. The old friction plate still had some friction material remaining, but one of the springs had become very loose.
The car was then left for about three weeks as it is only used as a second car. The next time it was used, I found the clutch pedal sank to the floor with very little pressure and I could not select any gears. However, all the clutch connections were bone dry, with no signs of leaks, so I assumed that air had somehow entered the system. I bled the clutch again using a Gunson E-Z Bleed tool, but could not detect any air pockets/bubbles, etc, from the clutch bleed tube. Afterwards, the clutch pedal still sank to the floor with little pressure.
Thinking it must be the master cylinder that had failed, I changed it for a new Lockheed unit and bled the system again. Initially, this did seem to improve things, but by the time I had the car back on its wheels, the pedal was still not operating the clutch.
Have you any thoughts about what is going on here? The only possibility I can think of is that the master cylinder had been stored for about 10 years, so could have degraded. Could the new slave cylinder be faulty? I thought slave cylinders could only fail due to external leaks, which would be obvious. There is obviously still air in the system, despite repeated bleeding. Gerald Reeves I am assuming that the clutch does not clear when it sinks to the floor, and that you don’t have an exceptionally light pedal. I say this because I have often been surprised at how light a new clutch can feel. When the slave cylinder fails, it is normally inclined to draw air into the system. Failure of new parts is quite rare, and providing the cylinder had not been lying around for years before it was sold to you, its failure is quite unlikely, albeit not impossible.
However, having been sitting for some years, the master cylinder could have dried out and failed, although I would expect this to result in a detectable leak from the pushrod seal. If I recall the system on your Saab correctly, there is a metal pipe going down towards the gearbox that has a flexible hose between the pipe and the connection to the slave cylinder (part no 4903670). You should ensure that this hose has not failed, as they do have a tendency to break down internally, although if that were the case I would expect at least a small sign of fluid around the pipe.
It may be possible to isolate the problem by bleeding out the clutch again, then clamping off the hose. If the pedal remains firm for some time, then the problem does point to the slave cylinder. However, you must remember that, with the hose clamped off, the pedal should not depress as the fluid cannot travel along to the slave cylinder. The only danger with this method is that if the hose has become fragile, clamping it may finish it off!