in the past when i started the engine, i would hear a "buzzing/humming" noise for a minute or so from the brakes. my understanding was that this was the brake power booster doing its thing.

recently, the brake pedal has become VERY hard to depress after the car has sat overnight (10 - 12 hrs or so), and i no longer hear the humming sound. after a few minutes, the brakes seem normal.

my understanding is that this is probably the "brake booster hose", volvo part # 30616993 gone bad.

before i spent $100 on this, i just want to see if this sounds like the most likely culprit.

thanks!

 

I have had this problem for a long time on my 2002 and my non-Volvo mechanic has checked and fixed some things but it persists. After starting it up in the morning or not driving for several hours, it takes a few minutes of driving for the brakes to act normally. It's very hard to stop, kinda dangerous at times when pulling out of the driveway into the street... Is this a defect?

 

Yes, it's broke. You should hear the brake booster pump noise when you have your foot on the brake and the car is idling while, say, backing up first thing in the morning. First check all fuses, then look for broken parts around the brake booster itself. If all checks good then I'd suspect the pump itself.

Now I have had an issue with new rotors and carbon metallic brake pads on my 2001. They did not want to work until heated. Switching back to semi-metallic pads fixed it.

 

From the FAQ:

Sorry if this isn't the case here. But it came up in another thread which I just read.

 

The brake recall was for 2000 models.

 

to test if is it the brake vacuum pump, have the key on position II. press the brake pedal for a few times, then you should be able to hear the a buzzing noise around the battery area. if not the either there is no power to the pump or the the pump itself is faulty.