I have a 2000 A4 Quattro. At start-up and then for about 3 minutes, the brake pedal goes all the way to the floor. After 3 minutes or so, the brakes tighten up and work properly. Is this normal?

 

Normal to have brakes that do not work????? I dont think so.

Can you pump the brakes and get them to tighten up? My first guess would be air in the lines somewhere. Also, audi reccomends changing the fluid every 2 years no matter what.

So, I would look for leaks anywhere, especially around the master cylinder, andthen try to change the fluid and bleed the brake system, and see if that fixes it.

I sure would be leary about driving that car at all, because a brake failure is a bad, bad thing if you are driving.

 

Listen to ^^

I have had that happen on two previous cars (not the Audi). Its usually air in the lines / master cylinder leak. Master cylinder leak btw, will cause air in the lines, so if you just bleed the system and it comes back in a few weeks, it probably because the master cylinder is shot. Also, master cylinders can get internal leaks (not drip brake fluid all over the floor and not lose fluid etc, so just because its not dripping, doesn't mean it isn't broke.

And yes, be very careful. When your foot hits the floor when you aren't expecting it and start pumping the brakes frantically, its not fun. Could take a few years off of your life.

 

This is either a leak in the brake booster or the check valve at the brake booster. As the car sits, the booster slowly loses vacuum through the leak. it then takes some time to rebuild boost. Fix it pronto.