Yesterday, I took my 86 420sel in for state inspection in Texas. This dude was checking the car and took off the power steering fluid cap off while the engine was running. The car was running very well prior to this. Since then, the power steering is making groaning noises at idle and on extreme turn. Gets better after driving a while. Belt looks tight. I added more power steering fluid. Wasn't sure of the brand. Is it Dexcron II?

Well the problem is still persisting. I had a 450sl manual (not 420sel), it states to keep turning the steering wheel from side to side to bleed the system. Is this correct? Do I have air in the system? What to do next? Is it another system?

Thanks,
John