If your 993 has a soft brake pedal caused by the ABS pump and not the master cylinder, I came across a rebuilder who can repair the pumps at considerably less cost than buying a new pump from Porsche.

The issue with the Porsche 993 ABS pumps seems to be that they experience an accumulation of white crystals and/or sludge internally in the channels/narrow orifices that results in a soft brake pedal.

The brake pedal is hard when stopping, however, once stopped, the pedal sinks another 1" or so when your foot is kept pressed on the brake pedal. Over time, I am told the problem gets worse and the brake pedal will sink to the floor.

From what I can gather, his is a widespread problem affecting many 993 cars, especially the 1995 and 1996 model years. The tech who works on my cars says Porsche should have recalled the pumps due to the sludge which is believed to have originated from faulty brake fluid from the factory.

I am told that if the brake system has not been flushed annually using the “hammer” device, the fluid goes bad and clogs up the ABS pump channels. Needless to say, many 993s have not been maintained to that standard - even Porsche recommends brake system flushes every two years, not annually. So many 993 owners may encounter this issue.

The new ABS pump from Porsche costs $1,600-2,000 plus installation (1 - 1 1/2hours). I came across a worldwide company (BBA-reman.com) which rebuilds ABS pumps and control units for many makes, including the 993 pumps. In their factory, they run DOT 3 fluid through the pump at high pressure while activating the pump valves thus cleaning out the sludge. The price is about half of a new pump and comes with a lifetime guarantee.

Just thought I'd pass this along.

 

Why not just flush the fluid every year?

 

Yes, ideally the 10-13 year old used 993 you buy would have had it's brake fluid flushed annually by the prior owner(s) using the "hammer" to activitate the pump during the flushes. However I don't see that very often with used 993 Porsches. Even Porsche's maintenance schedule recommends flushing the fluid only every two years.

Further, some Porsche techs believe that the factory fill brake fluid in the 1995-1996 993 Porsches was bad and resulted in a white crystalline substance clogging the ABS pump valves - like plaque building up on arteries and blood vessels. Over time, the white substance gets stuck in the ABS pump valves preventing the valves from tightly seating when closed, thus resulting in the loss of pressure and the soft pedal.

Last, if the 993 has the white sustance in the ABS pump, flushing the brake fluid in the system will not break it loose. The channels in the ABS pump are too small and narrow and only high pressure flushing while activating all the pump valves will blow this stuff out of the pump.