Brake booster

[Bob356]

I have the whistling air leak on my brake booster, hear it from inside the cabin. I do not think that it is the booster itself as it seems to function. When I apply the brake I get the vacume leak. The question is then, has anyone changed the O ring from inside the cabin rather than pulling the entire booster assembly out? The bellows on the inside then is a dust apparatus and has nothing to do with vacume sealing, correct? Any tips greatly appreciated. yes I found and read the excellent tutorial on removing the booster however my question is about the hissing, cause and repair.

Thanks

Bob
2001 XC70

[ericjp]

If you pull the boot on brake pedal shaft back, you'll see a while tube. I had the same whistle air leak and lubricated the outside of the tube with silicone grease which took care of it. Something to try before replacing the whole booster.