Porsche Enthusiasts Club Forum

Guys

I have replaced the rebuilt/resealed front calipers on my 924 auto, new hoses etc. Bleeding the brakes this morning but cannot get a pedal. There doesn't seem to be air in the fluid, there are no leaks and pumping the pedal repeatedly produces feel, but as soon as I stop pumping, all pressure is lost.

I got Mrs W to pump the pedal whilst watching the master cylinder reservoir. Nothing happens during the pumping to build pressure, but as soon as she stopped, fluid shot upwards from the bottom of the front of the reservoir hitting the top, then pressure is lost.

Am I right in thinking this is master cylinder seals?

Thanks

Yup the master is knackered! Sometimes when this happens you get bubbles make into the reservoir.
One thing I keep repeating is that if you're manually bleeding brakes or clutch. A. suck out fluid from the reservoir BEFORE you start bleeding, it reduces the amount of old fluid you pump through the seals, which is probably 60% crud!
B. And very important never pump the full stroke of the pedal when bleeding. The master only uses around 30-45% of its travel in normal use. By pumping full stroke you push the seals over rough areas that they never run over in normal use.
This is why perfectly good masters die after brake fluid changes.

Logically I would assume the same. Having just refurbished all 4 corners of the brakes on my 924, I had no such trouble, and the master cylinder is the only thing I didn't touch.

Additionally, I use the Gunson Eezibleed kit, which purely by chance, means that I didn't risk the problems that Jim describes.

Thanks guys-I think you've confirmed my suspicions.
Next question, can I get one from anywhere other than Porsche? (Approx cost £220)

I must get a recording done of this! I'd shop around JMG, Berlyn, ProMax, Euro car parts, German Swedish & French etc.

Exactly what I was intending to do-just wondering if anyone had a specific recommendation.....

Seems that they are Porsche only. Luckily, I was sitting down when they told me it will cost £220 and take a week to get from Germany.....

Not sure about autos spec but there are loads on ebay

Hmmm.. I should be able to get one, it could be ATE have been told to stop supplying them in the aftermarket by Porsche, but I should be able to make a call and get the same one as you get in a Porsche box, but without the Porsche box if you are still looking for an alternative to Porsche.

Hopefully you may find a cheaper supplier. That price is a little cheaper than the 944 cylinders for sure!