Als mogelijke oorzaak wordt de remvloeistof genoemd:
Bron: http://www.saabplanet.com/saab-9-7x-noi ... l-problem/
One possible cause for the noise is contaminated brake fluid, which tends to swell the seals in the master cylinder.
To make a definitive diagnosis, have a buddy apply and release the brake pedal while you pop your head under the hood.
GM DOT 3 brake fluid