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Help - Vacuum leak in Brake Booster 850 1994

posted by  fisher on  Mon Feb 18 17:48 CST 2002
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I just got a new 1994 850 Turbo and I love it. It is my first Volvo. One thing I noticed was, there is a hissing coming from the inside piston area of the brake booster. When I shut of the car, the leak slowly fades (5 sec) until there is no more vacuum asist on the brake booster so I am very confident it is the booster that is the problem. Also - at different brake pedal positions the sound is better or worse.

My question is - do I have to replace the booster or is there a seal in the front I can replace to fix this? I am hoping for an easier rather them more complex solution. Also, if I have to do the booster how difficult is that?

Finally - are these codes realted to this problem? ABS 141 and 142 (Pedal position sesor) and Fuel 435 (Front O2 Sensor slow)? I am guessing yes. The position sensor because maybe it is just a vacuum guage or something and the O2 cause I definately have a vacuum leak.

I do not want to take the car into the garage yet - I want to at least have a plan of attack. Any feedback would be very appreciated.

Thanks








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    Help - Vacuum leak in Brake Booster 850 1994

    posted by  Andries on  Mon Feb 18 20:23 CST 2002
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    Hi,

    Definately sounds like your booster is on it;s way and it could either be the diaphram or the valves inside and you'll most likely have to take the booster out. On LHD models it shoud be easy and is covered in the Haynes manual, basically remove vacuum pipe, undo the master cylinder bolts, undo the pedal clevis pin and 4 bolts inside the car. If you are lucky you don't need to remove the hydraulic pipes and you don't even have to bleed the brakes. If it's a RHD the manual states you almost need to go half way to get the engine out, drop the subframe etc but maybe you can get away by undoing the master cylinder , move it out of theway and get soemone to depress the brake pedal. Hopefully you can grab the pin on the engine side and lock it into place with a vicegrip. hopefully with some jiggling it will make it slightly easier then to take the booster out (this is a porsche 928 trick) .

    On the brake pedal sensor codes, you should have a look at Ozbrick, there is some pictures on what the thing looks like and how to repair.








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      Help - Vacuum leak in Brake Booster 850 1994

      posted by  someone claiming to be Steve on  Tue Feb 19 06:56 CST 2002 [RELATED]

      In addition to the above post be sure you check for leaks at the seals for the vacuum hose and the brake pedal position sensor on the front of the boster. It would be an easy fix if one of them were leaking.







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