Date: Fri, 5 Jul 2002 09:49:54 +0100 From: "Andrew Hookins" <andrew.hookinsnopsamamnopsamodata.co.uk> Subject: Re: 91 900 brake problem HELP PLEASE
Could be something simple - check the vacuum hose to the brake servo. Rubber hoses often perish at the ends, if it happens on the brake servo hose then you lose your 'power assisted' brakes. Or it could be the servo's vacuum non-return valve. Vaccum should hold for a few minutes after the engine is switched off. Test this by running the engine, then switching the engine off. Wait a minute then press on the footbrake pedal. Pedal feel should be normal. Pump the brake pedal a few more times and it will get harder as the vacuum is depleted. "KGee" <greenstingnopsam.com> wrote in message news:FD6V8.68689$B%3.13620nopsamnn01.usenetserver.com... > You will want the abs and foundation brakes checked by a Saab-familiar > mechanic as soon as possible. Brakes are not something to give you a second > chance should they fail completely. The most common failure causing hard, > stiff pedal is loss of accumulator pressure or a pressure-switch problem. > However if you notice the abs and brake lights coming on at initial starts > and going out within 20 seconds, it is most likely that some pressure is > building. One quick check you can do is with key and engine off note the > fluid level after pumping the brake pedal about 30-40 times. The fluid > level should be above the "max" level marked in the reservoir. This means > that you have exhaused any reserve (pressurized) fluid in the accumulator > and the fluid has moved into the reservoir. Start the car and wait for the > brake and abs warning lights to go out (may take longer than usual now), and > note the fluid level in the reservoir. This is at the point when the brake > fluid should be dropped back down to the Max or within a safe level > thereabouts. This indicates that the pump is able to pump fluid into the > accumulator and the system is attempting to build pressure for braking. > This should give you something to look at if the problem returns. Pull > over, keep car running, and look under the hood at the reservoir..fluid over > "max" with stiff pedal is a pressure problem. Could be an intermittent > failing switch. "Brandon" <brandon1nopsamultant.com> wrote in message > news:3d2293c5.37362869nopsamries.xmission.com... > > (luvdozer) wrote: > > > > > > >does anyone have any idea what this means? > > > > The fact that heat is a factor could point towards water in the brake > system. It's > > 'vapor-locking' in effect. If the brakes were serviced and the problem > started after > > that, I would check all points of connection for the slightest sign of > leaking. Brake > > fluid has the unusual property of attracting water. If it does so, it will > get in the > > system and when under pressure, boil or vaporize, generally minimizing > effectiveness, > > ie; no brakes. > > > > You may wish to have them flushed again, perhaps by a different shop or > mechanic. If > > there are no failing parts, in theory, the problem should go away. > > > > Cheers. > > >
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