Down a hill out of gear with the engine on, there is a regular kind of low hum in a straight line, when the car goes round a slight left curve the noise stops, when it goes straight the noise returns and I think it is still there on a right hand curve.

The noise is probably still there when in gear, just not as easy to tell with the engine noise.

Is this slack in the drive shafts?

Any ideas?

Sounds like a nearside wheel bearing, though if a front one the noise is usually louder turning right, (throwing the weight onto the nearside wheels) does the hum decrease as speed drops when out of gear ?

 

Jack the car up and spin wheels, you may hear the difference between good and bad, but more difficult during early stages of wear.

 

Alan.

Edited 20 April, 201511 yr by AlanRHB