Beny

Thanks for reply, I'll have to wait until after next week....the old fella took off to OZ once the border opened and the car is at one of those airport carparks. Anyway, after I changed the brake pads, I took it for a test drive and heard the air sound, then I bled all the brakes. One thing I noticed is when I opened up the bleeder on the 2nd brake caliper, no brake fluid came out when I pressed the piston back in, only on the first, just wondering if this had anything to do with it. Other than that, Im stumped too. EDIT: Also the outter right brake pad was worn more than the other 3, thepiston moved freely and the slides were all good (I grease all the slides).

No....would that make a difference?

Yes the brakes are working fine, its just that whooshing noise. So you cant just replace that silencer? been asking around and this booster unit is expensive (been quoted $480 and thats 2nd hand) and to make things worse, its a real arse to get to the booster as you have to take off half the car just to get it out from the engine bay and release it from the brake pedal. Oh well.

I can confirm it didnt make that noise before I replaced the pads. The "3 basic booster tests" were these ones:

Replaced my dads rear brake pads the other day, took car for test drive and now theres a whoosh sound every time I press the brakes (note: its not a constant hissing sound). Already bled the brakes so no air in the system, the noise is coming from the brake booster. I've tested the booster with the 3 basic booster tests from sitting in the car and it seems all good. Brakes are working fine, not spongy or anything, and the pedal isnt hard, its just the whoosh noise. Brake boosters are expensive (even 2nd hand) especially this car (2011 Nissan Serena), wondering if its a quick fix or a whole replacement required. Sounds exactly like this on the youtube clip: