Eh all.

My 89 260E makes a weird noise at all times. Its not the bearings as the sound continues even at a stop. Its hard to describe but a constant "wah wah wah" sound like a pump. I did the old turkeybaster method to replace the power steering fluid and it did'nt make a difference. Steering feels fine with no noise lock to lock. The master cylinder has been replaced before I bought the car not long ago. The fuel pump gives a healthy electric buzz sound.

Suggestions as to where to look?