1998 Cadillac STS

I just recently replaced the rack and pinion and high pressure line on my 98 Cadillac STS. I had read several things online about it's problems and difficulty replacing it and I actually had access to a lift which made it not that bad to replace. Well when I was all done I lowered it down to fill it up with fluid, I filled the resevior up and started it up, it ran fine for a minute and then I noticed the fluid was being sucked down at a rapid rate, no leaks though, I just figured the pump was sucking it down so I kept filling it, after about 30 seconds it seemed weird because it kept sucking it down. All of a sudden out of nowhere I heard a loud pop almost like a gunshot and fluid starting pooring out of the bottom of the car. I checked underneath and it was definately the rack, apparently it blew its seals. I know it is destroyed and will need to be replaced again, but what caused this to happen, did I do something wrong, did I leave something out, is the rack faulty. What do I need to do to keep this from happening again?