Ok heres the problem, about a few months ago I bought one of those do it your self kit to rebuild the vacuum pump (the common oil leak problem). Did it in 20min. Ran fine with great vacuum but it all changed when the cold weather came. I notice every cold morning or day I have no boost in the brakes and same for the heater box. I just replaced the master and booster and starting to think thats the problem. But the weird thing is if I just press the pedal just a little bit all of the sudded I get some vacuum and I see the fresh air door open and close. It usually gets stops at half way because of the lack of vacuum pressure. I pulled of the vacuum hose and notice it is making a slurping sound. But not sure if thats normal. I don't believe its the heater box because I just replaced the lines. The only thing I havn't really check is the cruis control system. But can anyone give me a hint where to start? I don't know if I should just replace the booster or start from the vacuum pump. Also does anyone know what the vacuum pull should be? I have a tool that I havn't used yet. I figure its the best time to use now. Sorry for the long confusing writting but i'm so confused myself. Please help!

 

well I finally managed to get myself off my big fat butt and go do some testing. I isolated everything down to the booster it self. The pump was pulling a steady 27. About 25 in the system. I noticed that when I hit the brakes the gauge will drop to about 15-10. But what was disturbing was it took about 30sec to get back up to around 25 at about 2000-2500 rmps. I pulled a vacuum on the the cruise control system didn't show any signs of leaks. Same with the a/c system. And pump was clearly working at max regardless of rpm range. So the only thing left was the booster itself. I guess I got a defective booster. Really sucks but at least I have the experiance and lifetime replacement plan.

 

Replace the master and booster at the same time. The most common cause of booster failure is brake fluid leaking out the back of the master. Most parts stores will sell you a "loaded" booster with the master already mounted for less than the price of the two parts separately.

 

they were replaced at the same time should I just exchange both of them?

 

How long ago?