Hi,
I just drove my 1984 mercedes 300D from wyoming to portland, or and by the end of the trip my power steering became very loud when turning. A sort of growling that would vibrate throughout the column. It occurs the most loudly when:
1. turning left

2. at low speeds or starting from a stop

3. turning very sharply

I checked the fluid level and it is barely over the circlular part of the pump with the holes in it. Should it be higher? Also what type of fluid should be used if this is actually the problem. If it is of any help on the same drive for about half of the trip the car refused to go above 60 mph. This problem has since disappeared.

Thanks
Sam