Help! Brakes Buzzing?

[Ju2]

Ok, so I searched and found a couple threads that kind of helped. But I'm looking for something a bit more specific. I have a 00 GS300, and as of recently, my car hasn't been getting much use. However, last week when I went to drive it, this loud buzzing noise, noticeable from inside & out of the car started going. Its coming from the brake master cylinder/booster/accumulator, not sure which or where specifically. At the time, the 40 pumps before checking the brake fluid was unknown, so someone (not me) started putting more & more brake fluid in the reservoir, which of course, was not needed. Which then led us to believe there was a leak, when there wasn't. Needless to say, we know there isn't a leak, only a former lack of knowledge.

So here is what my car does, after starting, it does the loud chirp/buzz thing, like an alarm from the cylinder, no lights are on the dash, but if you step on the brakes, you can hear a "click" come from the center console where the shifter is, then after 5 to 10 minutes, the noise is a solid buzz, and the VSC warning light, the VSC OFF light, Brake & ABS light come on for about a minute, then all of the noises stop for a while, 1/2 hour or better, then start again. Guessing its my master cylinder, but any help or suggestions would be much appreciated.

I have a couple videos I took yesterday, can email to you if you think it would.

-Ju2

[Silver 98 GS300]

I am having trouble getting a consistant brake pedal after rebuilding the master only. I had buzzing too after the install untill I got some fluid in the system but the pedal still goes to the floor when pushed slow to normal. Pushing fast seems to apply the brakes but you can't drive like that.

What exactly is the "40 pumps" method?

[nc211]

Interesting thread, as my new-to-me 01 GS430 has this buzzing/humming noise too from the master cylinder area, especially when I start the car, and when I press the brakes for like the first or second time. It's a "buzzzzz" followed by a "click". I can tell my brakes are worn out, and I'm pretty sure they're aftermarket parts "bought it used with 56k miles recently". I know the car was recently serviced at the Lexus dealer for the 60k service, before the previous owner traded it in. On that receipt shows the brake fluid being replaced, and it certainly appears to be new. I'm wondering if there is some air in the system from a rushed or botched bleeding procedure? Or, the caliper piston is damaged, here is why I think that:

I have an 05' 4runner, and right before we moved to Chicago, I replaced all the rotors and pads with new OEM. The 4runner now also makes that buzzing noise. When I was doing that proceedure, I noticed one of the caliper pistons "front driver's side" was actually starting to rust and flake "thanks to the Chicago road salt". This car, altough bought in NC, was a single owner car, from Illinois as well "go figure". Bought it too with about 56k miles "now has 72k". When I was doing that proceedure, I accidentally bled the caliper a bit on the driver's front caliper. I caught the problem, reattached the line to the caliper, but forgot to bleed out the caliper "I simply added some new fluid in the reserve to make up for the lost fluid". So, I'm wondering if there is some air in that caliper housing now too. I'm willing to bet there is. Or, the piston is so damaged that it's hitting the back of the pad at an uneven angle, causing it to twist a little, and creating a pocket of uneven pressure? I have no leaks in either car, but I find it odd that both have had their brake fluilds altered, and now both buzz. Both stop fine, peddle fell is good. The GS wanders a bit "wornout pads", but when asked, it'll stop hard. The 4runner stops like it's a new truck.