156/147 clutch hydraulics
Discussion
This subject comes up with monotonous regularity and is a serious pain in the butt.
These cars are prone to failure of the slave and master cylinders. There are 2 problems associated with this. In the majority of cases there is no leak of fluid, only loss of pedal pressure. In my experience this is almost unique in systems with annular slave cylinders. Furthermore, bleeding the system results in instant restoration of pressure, sometimes for weeks, and this is the baffling part of it.
The master cylinder is so badly situated it is quite frankly, a bloody disgrace, and Alfa should be ashamed of themselves for such poor design. Replacement involves a great deal of torturous work under the dash and behind the pedal box. If you are small and skinny it helps!!
The annular slave cylinder was invented by Saab in the mid '70s, but was used in their transaxles mounted under the engine which had the clutch housing at the front with an ingenious system that permitted removal of the whole clutch assembly just by taking a cover off the top of the bell housing and withdrawing the first motion shaft from the clutch. This made it very simple to change if it failed; it very seldom did.
Now to today's technological wonders. Both the cylinders on the Alfa are made of plastic, and my theory as to why they fail in the manner that they do is caused by temperature differences. Plastic shrinks from long term usage, and I think the seal starts to draw in air when the vehicle is sitting and the temperature drops below a certain point, permitting air to pass the seals.
I say this because the 156 I have just done is my wife's car and the problem only started when this cold spell came in. Upon removal I discovered a small leak from the master cylinder but I have replaced it with a steel one. Unfortunately the system is still drawing air but is not leaking fluid so I will have to do the slave as well.
This involves removing the whole transmission assembly; not a 5 minute job, even with the right equipment. This brings us to the heart of the matter. As someone already said in another post, almost all cars are using annular cylinders now. The reason manufacturers are doing this is because it's cheap. This policy is to me totally unacceptable, because the cost of replacement is completely disproportionate to the part being replaced.
Sadly I find design like this in many aspects of modern cars, and it has got to the point where scrap yards are full of perfectly good vehicles that are uneconomical to repair due to bad design: a sad endictment on present day designers.
The problem is they don't have to fix the bloody things when they go wrong!
J
These cars are prone to failure of the slave and master cylinders. There are 2 problems associated with this. In the majority of cases there is no leak of fluid, only loss of pedal pressure. In my experience this is almost unique in systems with annular slave cylinders. Furthermore, bleeding the system results in instant restoration of pressure, sometimes for weeks, and this is the baffling part of it.
The master cylinder is so badly situated it is quite frankly, a bloody disgrace, and Alfa should be ashamed of themselves for such poor design. Replacement involves a great deal of torturous work under the dash and behind the pedal box. If you are small and skinny it helps!!
The annular slave cylinder was invented by Saab in the mid '70s, but was used in their transaxles mounted under the engine which had the clutch housing at the front with an ingenious system that permitted removal of the whole clutch assembly just by taking a cover off the top of the bell housing and withdrawing the first motion shaft from the clutch. This made it very simple to change if it failed; it very seldom did.
Now to today's technological wonders. Both the cylinders on the Alfa are made of plastic, and my theory as to why they fail in the manner that they do is caused by temperature differences. Plastic shrinks from long term usage, and I think the seal starts to draw in air when the vehicle is sitting and the temperature drops below a certain point, permitting air to pass the seals.
I say this because the 156 I have just done is my wife's car and the problem only started when this cold spell came in. Upon removal I discovered a small leak from the master cylinder but I have replaced it with a steel one. Unfortunately the system is still drawing air but is not leaking fluid so I will have to do the slave as well.
This involves removing the whole transmission assembly; not a 5 minute job, even with the right equipment. This brings us to the heart of the matter. As someone already said in another post, almost all cars are using annular cylinders now. The reason manufacturers are doing this is because it's cheap. This policy is to me totally unacceptable, because the cost of replacement is completely disproportionate to the part being replaced.
Sadly I find design like this in many aspects of modern cars, and it has got to the point where scrap yards are full of perfectly good vehicles that are uneconomical to repair due to bad design: a sad endictment on present day designers.
The problem is they don't have to fix the bloody things when they go wrong!
J
I think your reasoning behind the failure could be spot on. My GT master cylinder failed in the cold and got better when the weather warmed up.....until it went cold again and there was no pressure!
I replaced the Master Cylinder and three weeks later the slave went! However I was lucky as the 1.9JTD has the slave mounted on top of the box.
ALSO WARNING TO ANYONE READING THREADS ON SQUEAKY CLUTCH PEDAL
Never use silicone spray or lithium grease to stop the squeak - I did and the seals were as soft as Dairylea when the failed cylinder was removed. If it squeaks leave it or replace it.
I replaced the Master Cylinder and three weeks later the slave went! However I was lucky as the 1.9JTD has the slave mounted on top of the box.
ALSO WARNING TO ANYONE READING THREADS ON SQUEAKY CLUTCH PEDAL
Never use silicone spray or lithium grease to stop the squeak - I did and the seals were as soft as Dairylea when the failed cylinder was removed. If it squeaks leave it or replace it.
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