bad brakes
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Joined: Jul 2007
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bad brakes
my brakes have been acting up lately. I replaced the master cyclinder, no change. the first brake application opperates normally. applications after that brake pedal is very firm requiring a large effort to get braking action. have checked vaccum booster and it appears to be normal. all brakes have been bled. appears to be no fluid leaks. problem is quickly getting worse. i am thinking a bad brake booster. is there a test to definitly determine a bad booster. ideas please!
FTE Leadership Emeritus
Joined: Sep 2000
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From: Stephensville WI
The vacuum booster could have a leak that won't cause the engine to run rough, due to the check valve.
It sounds to me like it is the brake vacuum booster that is bad. You get enough vacuum assist for one application of the brakes.
It sounds to me like it is the brake vacuum booster that is bad. You get enough vacuum assist for one application of the brakes.
Post Fiend
Joined: Feb 2007
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From: Blairsville,Ga
Originally Posted by redford
The vacuum booster could have a leak that won't cause the engine to run rough, due to the check valve.
It sounds to me like it is the brake vacuum booster that is bad. You get enough vacuum assist for one application of the brakes.
It sounds to me like it is the brake vacuum booster that is bad. You get enough vacuum assist for one application of the brakes.
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 23,174
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From: Stephensville WI
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it is a bad vaccum pump. had this happen before. you can take the vacuum line off the booster and hook a gauge to it.
With the engine running at normal operating temperature, the vacuum pressure should be 57-70 kPa (17-21 in-Hg). Once the engine is stopped, the pressure should not drop more than 3.4 kPa (1 in-Hg) after one minute
With the engine running at normal operating temperature, the vacuum pressure should be 57-70 kPa (17-21 in-Hg). Once the engine is stopped, the pressure should not drop more than 3.4 kPa (1 in-Hg) after one minute
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Post Fiend
Joined: Feb 2007
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From: Blairsville,Ga
Originally Posted by redford
Yes, that would also be a culprit on a diesel.
Or...did the 97's have hydroboost?
Or...did the 97's have hydroboost?
