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Solution for soft brake pedal caused by ABS pump

Old 03-19-2009, 08:43 PM
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SKM
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Default Solution for soft brake pedal caused by ABS pump

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 ôhammerö 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.
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Old 09-06-2009, 10:58 PM
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Mark in Baltimore
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Back from the dead. Excellent post. I am having a similar issue.
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Old 09-07-2009, 12:07 AM
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Originally Posted by Mark in Baltimore View Post
Back from the dead. Excellent post. I am having a similar issue.
Let's try the one-hour solution first...


Andreas
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Old 09-07-2009, 09:47 AM
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The soft brake pedal caused by the ABS pump being clogged is very distinctive vs. a spongy brake pedal due to air in the system or a bad master cylinder.

I have a freshly rebuilt ABS pump for sale for 993 models with LSD and ABD options.
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Old 09-07-2009, 10:01 AM
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Originally Posted by AOW162435 View Post
Let's try the one-hour solution first...


Andreas
Agreed.

Originally Posted by SKM View Post
The soft brake pedal caused by the ABS pump being clogged is very distinctive vs. a spongy brake pedal due to air in the system or a bad master cylinder.

I have a freshly rebuilt ABS pump for sale for 993 models with LSD and ABD options.
Thanks, SKM. I have a Guards LSD but no ABD, so I'm not sure if the pump is the right application for my car. I'm going to try a thorough flush and then go from there.
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Old 09-07-2009, 10:05 AM
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Mark:

I have a fix for this problem. I have done it 2 times on 2 different cars and has worked perfectly. Nice thing it only costs a little time and a few dollars ($5.00). PM me your number and I'll walk you through it. BTW both cars I did it to had the ABD option w/locking diff. Just FYI.

Mike
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Old 09-07-2009, 05:30 PM
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Would be nice to share with the rest of us! Have hard peddle now but may need help when older.

If you could put the procedure here for future referance that woiuld be great.

Jeff
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Old 09-07-2009, 05:35 PM
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Likewise
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Old 09-07-2009, 06:45 PM
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Originally Posted by Arena993 View Post
Mark:

I have a fix for this problem. I have done it 2 times on 2 different cars and has worked perfectly. Nice thing it only costs a little time and a few dollars ($5.00). PM me your number and I'll walk you through it. BTW both cars I did it to had the ABD option w/locking diff. Just FYI.

Mike
Thanks, MP!
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Old 09-08-2009, 01:54 PM
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I too would really like to see a quick write up of your procedure, Arena 993 if you could? thanks
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Old 09-08-2009, 03:19 PM
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I had similar issues with my first 993 (Targa). As I have documented in other strings, I had a white, waxy thick substance in my brake system. It was due to lack of frequent brake fluid flushes. Moisture accumulates in the fluid and it hardens.

While I paid up and replaced my master cylinder and had it flushed multiple times, I since learned a better solution.

Unfortunately, I have forgotten the exact specs, but the solution was to flush out the old brake fluid and replace it with an older DOT version. Leave the older version DOT fluid in the car for several days and it desolves the waxy stuff. Flush with the correct, newer DOT fluid and all is fixed.

Hopefully this makes sense. If not, search the archives for specifics.

I sent my old clogged master cylinder to Paul Reiser (PCA tech advisor) for him to study per his request. Not sure if he ever did anything with it or found a fix.
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Old 09-08-2009, 06:37 PM
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Originally Posted by Arena993 View Post
Mark:

I have a fix for this problem. I have done it 2 times on 2 different cars and has worked perfectly. Nice thing it only costs a little time and a few dollars ($5.00). PM me your number and I'll walk you through it. BTW both cars I did it to had the ABD option w/locking diff. Just FYI.

Mike
Mike,

I shot you an email at your automotion account.

Originally Posted by pjconner View Post
I had similar issues with my first 993 (Targa). As I have documented in other strings, I had a white, waxy thick substance in my brake system. It was due to lack of frequent brake fluid flushes. Moisture accumulates in the fluid and it hardens.

While I paid up and replaced my master cylinder and had it flushed multiple times, I since learned a better solution.

Unfortunately, I have forgotten the exact specs, but the solution was to flush out the old brake fluid and replace it with an older DOT version. Leave the older version DOT fluid in the car for several days and it desolves the waxy stuff. Flush with the correct, newer DOT fluid and all is fixed.

Hopefully this makes sense. If not, search the archives for specifics.

I sent my old clogged master cylinder to Paul Reiser (PCA tech advisor) for him to study per his request. Not sure if he ever did anything with it or found a fix.
Thanks for the info, Patrick.
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Old 09-08-2009, 07:04 PM
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Mark:

That email is NLA. PM sent with # and new email.

Mike
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Old 09-08-2009, 09:19 PM
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Originally Posted by Mark in Baltimore View Post
Mike,

I shot you an email at your automotion account.


Thanks for the info, Patrick.
No problem Mark. I highly suggest that you at least try what I stated before you start replacing parts. Cheap solution and hopefully effective. Good luck.
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Old 09-09-2009, 02:27 AM
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I spoke to Mike today and he was most gracious and detailed with his explanation. further flushing of my system seems to have solved my problem. But good info to have in the future. thanks again Mike - is RL a great place or what????
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