So I bought this car and right away I noticed the brakes were spongy. They work really well the first couple of times doing a moderate stop but after going down a big hill or using them a bit they get really spongy and don't work well . I have discs in the front and drums in the rear. I changed my front pads and still not great and then I bled the valves starting with the farthest away from the master filling the reservoir as I go. After I bled all 4 a bunch I decided to go back and do each one once more. When I went back to the rear passenger where I started I had my partner pump the brakes and hold and I turned the valve open but not much fluid came out. I thought that was a bit weird so I went to drivers rear and did the same procedure and no fluid came out... Tried a couple times. The whole time I was doing this I kept the brake reservoir topped to the max. So I stopped there and went for a drive. Still the same. I want to know what I should do next. Master cylinder? Drum brakes? Any advice