Brake Problems - Vacuum?

[smlytle]

Okay, so my gf has a 1996 Lexus ES300... she takes great care of it, makes sure it gets regular maintenance, drives it easy, etc...

The other day I when she pulled into my parking lot I heard a screeching sound as she came in and parked. i automatically assumed it was the screech plate that they put on the brake pads when they get low. I told her she needed to get it fixed. The next day she was driving on the road and when she went to stop she said the car would not brake at all and she was pushing the brake pedal to the ground.

Obvioulsy this alerted me that there was a bigger problem. She took it to her mechanic yesterday and he said he can't figure out what the problem is but that she shouldn't be driving it because when he test drove it he saw the same issues. He also said he checked the pads and they were fine. he told her to go to the Lexus dealership and pick up a Brake vacuum check valve (they wanted to charge her $60) and he would see if that was it. However, he said if this is not it then it could be something more serious and could cost her over $1000.

Heres the two issues... one I would like to figure out what the problem possibly could be and two I dont know how he could possibly know how to price the "fix" if he doesn't even know what the problem is.

So, in short, the symptoms are the car will not brake without holding the brake down with a lot of pressure and there is a audible squeeking noise which sounds like it is coming from the back wheels and the brake pads are fine.

has anyone heard of this problem before or know anything that may help me determine what the issue is? Thanks so much.

[kingjack133]

some things to check;

1. malfunctioning power brake booster

2. piston in calliper or brake cylinder stuck or sluggish

3. contaminated pads(oil or grease) or not properly seated pads.

[smlytle]

Thanks I will def look into this.