Viking1064

Hi All,
About 3 weeks ago I brought my '02 Pontiac Montana to the dealer. Something broke with the back brakes. They were fixed under warranty. THe service guy recommended have the brake lines flushed out to get rid of any debris and/or dust. I said OK. Well on Monday tow weeks after it was fixed the brake line broke. Thankfully I was driving it because she would not have know what to do. The dealer said it was very uncommon to see that happen on such a new vehicle and it was unrelated to the work they did on it. I was skeptical but what could I have done? Well I go the van back on Wed. Today, Saturday I am an hour away from home doing 70 MPH on a highway and guess what? No brakes again!!! Can anyone tell me what they thing the service department may be doing wrong? This is scary. It is scheduled to be worked on first thing Monday. I want to see it go on the lift and see the brake line before they get to it.