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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22893
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a 1989 Audi 100 Avant 2.0E engine code RT whose

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hi, I have a 1989 Audi 100 Avant 2.0E engine code RT whose brake pedal travels to the floor on engine start-up and the red warning light illuminates [engine off pedal is solid], I have replaced the master cylinder and bled the system 4 times but the problem still persists, can you help please, many thanks,dave
Customer: replied 2 years ago.
I have done a preliminary check on the rear brake pressure regulator and it appears to be functioning. When the engine is switched off the pedal immediately goes hard again indicating that the brake bomb may be faulty, could this cause the pedal movement problem. Regards, Dave
hello Dave I'd agree that this sounds like the 'bomb' has failed and is leaking internallyso I'd suggest to test it as follows:One test for the accumulator, is to run the engine for a few minutes, turn off the engine, and then pump the brake pedal until the pedal feels hard, (no more power assist). Normally with a good, working brake accumulator, this test takes 25-35 pumps on the pedal before the pedal gets hard. If the pedal gets hard with only a few pumps on the pedal, the brake accumulator is defective and should be replaced.
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Customer: replied 2 years ago.
Thanks matt i did the check and as soon as the engine stopped the pedal went solid. Will replace when new one delivered