I think you've still got air in the system. GM has a special tool, which is really just a rubber plug to fit the PS reservoir cap nozzle, a hose barb, and a small reservoir to catch fluid. Here's a video of it in use. Bleeding your power steering - the GM way - AL, United States, AutoPro Workshop Video - Where Professionals Gather for Better Business I've heard of guys using an old cap, drilling it to fit a plastic hose barb, and then using a standard vacuum reservoir to catch fluid to keep it from sucking into the engine.