In article >, says...
>
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>On 6 Jul 2005 16:39:50 -0700, wrote:
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>>>
>>Now I'm not a mechanic, but I'm having a hard time believing that the
>>master cylinder just happened to give out when it did.
>
>
>You would most likely be correct. The master cylinder tends to get
>rust and gunk in the bore because you only push the pedal so far down.
>When the brakes are bled if you push the pedal to the floor then the
>seals in the master cylinder get torn up by the rough surface. Once
>the seals are damaged fluid leaks by them internally in the master
>cylinder causing your pedal to drop.

This is one reason why you want to change your brake fluid regularly. So
that you don't get this crud accumulating in the MC and so that the water
that mixes with your brake fluid doesn't rust out the brake system.

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Alex