JD15

After returning from a four and a half day trip, I found that my brake pedal was close to the floor and my brakes had no pressure when trying to start the car. After starting the car, pressure returned as expected and the brakes felt normal when driving. Is it normal for the A4 to lose brake pressure when sitting for long periods?

I've never had this happen with any of my previous cars, so I am trying ascertain whether this is normal behavior or whether my car has a brake issue. My A4 is less than a month old and this is the first time that it has gone more than two days without being driven.

GR8-LIFE

I had an interest in an 04 SL55 AMG a couple of weeks ago. Sweet car, 43K miles and selling for only $35K. When I saw the car's service history, the car had 2 Brake Hydrolic Pump Recalls. So I post on the MERC forums and an AMG owner described similar symptoms as what you described. The AMG had a chit load of other reapirs too so I didnt wantto touch it. Man, I can been I'm, walking away from an SL55 AMG for a pre-owned AUDI A4 to add to my stable!

snagitseven

Not normal. Have it checked asap.

matthewsjl

Not sure that I agree it's "not normal".

If you get in the car cold and it's been sitting for a while, if you press hard, your foot can go significantly towards the floor with the engine not running. If you release and re-press, you should feel more resistance and the pedal shouldn't go to the floor.

If the car is started and you press, you shouldn't be able to put your foot to the floor. You should just press and feel normal resistance.

It's all to do with the braking assistance and how the pressure is managed.

John.

JD15

The brake pedal felt fine this morning. It seems that, for now, this issue will only occur when the car has been sitting for at least a few days. Last night, however, the pedal was practically stuck close to the floor until I started the engine. Could this be indicative of a slight leak in the brake vacuum booster?

matthewsjl

If you pump the brake with the car *not* running, does it firm up?

I still don't think it's a problem.

John.

JD15

Yes, if I pump the brake several times with the car off, the pedal firms up and loses its range of motion, which is the same as with other cars that I've owned. The issue that I had last night is that the pedal felt like it had been pumped with the car off, but had not. Since the pedal must be pressed to turn on the ignition, I had to apply significantly more force to the brake pedal than usual to start the car.

trlyka

If you felt you had to use more pressure to start the car, then have it checked to be safe. No need to worry needlessly and brakes aren't something to mess with, especially if there is a leak.

I used to own a '72 Corvette...aka money pit....Now I know todays cars are obviously built different, but I used to drive it when I knew the booster was going bad (or at least I think it was the booster) and I was loosing pressure. I would slow down using the gears and it was an automatic. Not good I know, but I did what I had to do until I could get it fixed each time this would happen.

My point is to be safe then sorry. And the money we pay for these cars, it should be flawless out of the box and shouldn't be making you feel like something isn't quite right.