Air Whooshing When Hitting Brakes | Lexus IS Forum

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jwis300 J Hi, I just tried to replace my rear brake pads today because I though they were done for...turns out theres plenty of life left....so I put it back in....I also opened the brake fluid reservoir cap because I thought I was supposed to during this process....anyways I assemble everything back together and go for a test drive and I notice an air noise coming from hitting the brakes.....I'm pretty sure I never heard it in the last few months of owning this car...but I usually have music on...but I noticed it right away after this test drive.....Do I have to open the cap and start the car and pump brakes or something? #1 · Jul 9, 2013 Hi, I just tried to replace my rear brake pads today because I though they were done for...turns out theres plenty of life left....so I put it back in....I also opened the brake fluid reservoir cap because I thought I was supposed to during this process....anyways I assemble everything back together and go for a test drive and I notice an air noise coming from hitting the brakes.....I'm pretty sure I never heard it in the last few months of owning this car...but I usually have music on...but I noticed it right away after this test drive.....Do I have to open the cap and start the car and pump brakes or something? Sort by Oldest first Oldest first Newest first Most reactions #2 · Jul 9, 2013 Since you didn't open a brake line there is no way you have air in your system, especially if your reservoir has a proper level of fluid. You mentioned to me about having to pump the pedal up a bit so the pedal gets stiff again, that's completely normal because the pistons are extending back to where they were. The swooshing air noise you're hearing is at the pedal when the car is running? #3 · Jul 11, 2013 any fluid leaks? it wouldnt make much sense, but on an off chance... #4 · Jul 14, 2013 The other thing I'd check, is if all of your bleeder screws are tight and not leaking. A simple check could be to park the car, put cardboard under each wheel and pump the pedal once or twice. If you see a few drops, the bleeder screw may be loose. You would need to bleed out any air through that bleeder before you close it again, as well. Alternatively, someone might suggest the master brake cylinder is failing, but i'm not familiar with troubleshooting for that. While you were working on your brake pads, did you pump the brakes with the reservoir cap off? You could easily have drawn air in that way. (I've done it on two cars). #5 · Jul 14, 2013 the only reason to pop the cap off the reservoir is to make it easier to compress the caliper pistons back in place. pumping the brakes or messing with lines will definitely pull air into the system without care. NEVER pump any hydraulic system when it's open. either way, the pistons should never be forced (take your time compressing them) but if your car stops like it did before there probably isn't an issue. did you lube your slider screws? does your pedal travel further than before? any other noticeable noise? there is no need to pump your brakes with a simple pad replacement. #6 · Jul 16, 2013 only thing I can imagine is brake booster. park your car and turn engine off. hit the brakes, you should hear a hissing sound that is coming from brake booster. thats normal. pump the brakes few times and brake pedal should get stiffer each time and hissing sound should stop, because you are releasing vacum from brake booster. when engine is started, brake pedal should get soft again, that is because engine creates vacuum for brake booster to work. when all vacuum from brake booster is gone brake pedal should get very very stiff. thats a good sign. when you replaced your brake pads you pressed brake cylinders back? if so then first few brake presses should be longer (deeper), that is because cylinders need to extract untill pads make contact with rotor. anyway - if your brakes get stiff with engine off after pumping pedal few times, you should be fine

#7 · Jul 16, 2013

lex2oos said: anyway - if your brakes get stiff with engine off after pumping pedal few times, you should be fine Click to expand...

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