Brake Bleeding

[PJorgen]

I understand that the Porsche Service Manual recommends against bleeding the brakes using the old-fashioned pump-the-pedal technique. Any idea why? I've done it this way with my P-car and a whole stable full of Audis for years, with no apparent adverse affects.

Anyone shed some light on this?

[RFM]

The pump-the -pedal technique is a 2 man job for a good result, bleeding the hydraulic system with a machine is a 1 man job.

For older types 4 wheel drive Porsche's ( 964-993 ) is a machine recommended + PST2 to bleed the entire system.

[eshuber]

The only reason I can think of not to use the "pump the pedal" technique is overtravel on the master cylinder - i.e. the master cylinder seal may be damaged when is goes into the bore area not normally used. I know - using this method resulted in master cylinder failure on an Audi immediately after doing a brake bleed.

Get a pressure bleeder - they are cheap and easy to use.

[GOB]

I did bleed my brakes with the help of another person (certified Porsche tech) and it was fine. Here is a hint: put your left foot against the "firewall" so you do not over extend the reach of the brake pedal. That way, you avoid potentially breaking the master cylinder seal. It can be done, but it takes two people (one pumping the pedal, the other opening and closing the nipples on the calipers) and making sure to pump the pedal slowly and not all the way to the bottom. It can be done, just follow the procedures mentioned.

[PJorgen]

Thanks for the info - that makes sense. I always used an assistant (my wife) but she's sometimes not available. Guess I'll break down (ha!) and buy a pressure bleeder.