After driving 20km or so on winding roads a humming sound starts and becomes louder especially while turning the steering wheel in either direction. It's quite loud by the time I stop. If I leave the car for a couple of hours and start driving again and avoid winding roads the sound doesn't return.

The power steering fluid is at the level it is supposed to be and is not over heating.

I bought the car used a few days ago. It has 86,000km on it and has had no accidents or major repairs.

Any advice is appreciated,

MM

 

Check the condition of your tyres and also the front wheel bearings for any sign of play or excessive heat buildup in the hubs.