I just changed the brake pads myself for the first time after reading some of the helpful diy threads. It was fairly straight forward and luckily no issues after a week. I've been reading up on the diy gravity bleeding of brakes and I attempted to do it today. I've run into an issue that I can only pump the brake a few time before it becomes so hard that I can depress it anymore. This happens while I have the hose connected to the bleeder valve and the bleeder valve open and the engine off. I topped off the master cylinder before doing this. I decided to start the car and the brake pedal was fine after that. Questions: Am I doing something wrong? Do I need to start the car after a few pumps on each wheel? Any help would be appreciated.