i'm workin on my brothers 89si and while bleeding the brakes i heard the woot, this added to his complaints of poor braking and idle problems have led me to test the booster. i don't have the mc pressure tester gauge, so how should i test the booster for seal failure?

i did try and pull a vaccume and no way, it's free breathing in and out of the booster. the check valve is working and facing the correct direction. does this mean the booster seal broke? it should hold a vaccume correct?

thanks in advance for your replies

 

nvr mind, it's bad, gonna swap it today