QuestionQUESTION: I have a 2000 Grand Am 6 Cyl SE. On start up in the morning, backing out of
the driveway, it feels as though the power part of the power brake system
isn't working. I feel like I need to "stand on the pedal" to stop. It then seems
to "loosen up" to normal. It's like it's stiff, or the mechanism is stuck. It feels
like the pedal is on the floor, until it breaks free and is normal. As soon as
that is over, they are fine. No other problems. I have had them checked. All
pads, etc. are OK.
This only happens after the car has sat for hours. It can be in drive or
reverse. I can push the pedal until it loosens up before I back out. That
works. It's intermittant, though, so some mornings I forget because it was
OK the day before.
I have a great mechanic and he can just start replacing stuff like the master
cylinder and/or power brake parts, but I am searching the internet for
someone who may have seen this issue before and know the answer.
ANSWER: Hi patti:
This is a tough one to tell you over the internet. Without actaully feeling what your talking about. It could be one of three things. #1 the brake booster is leaking down and the first pedal effort is really tough untill the unit is full of vacuum again. It can be the check valve leakiing or the diaphram inside the unit leaking. #2 the master cylinder is on it' way out. The first brak apply the fluid leaks past the seals in the unit and when the fluid leaks past it it created enough heat that the seals swell up and from that point forward it's fine. #3 and least likely "crappy" quality pads that give you a vaugue brake pedal feel untill they have warmed up. My guess is #2 is the most likely cause but like I said it's hard to actually tell you for sure with out experiencing it myself. Everyones interpitation of a problem is different. It can be the same problem and 3 people discribe the feel a different way. Hope that helps you out some? Good luck :}
---------- FOLLOW-UP ----------
QUESTION: Thanks for the quick reply and thorough response! For #1 would there be any
way to see if the unit was leaking, or is it internal? Both #1 & #2 sound like what
it feels like. I'm just hoping to find evidence before I flip a coin and get one of
them replaced. :-)
Answerit is internal. If you have a hand held vacuum pump and an adaptor to hook up to the booster you could fill it up with vacuum and see if the vacuum bleeds down. you could also after the car sit for a while pull the check valve out of the boster and you should hear the air rushing into the booster. If it has no vaccum in it then try this to check if it's a booster check valve use a pair of vise grips and pinch off the hose and let the car sit then try again if you still don't hear the air rush in the booster is leaking.
