odd wheering noise, only when in gear

[tomothy94]

Since a few weeks ago now, whenever I get to about 30-40 mph, there's a really odd 'wheeeeeee' noise over the top of the engine. after I get to 40 the noise becomes noticeably more quiet, but it is still present. When rolling along in idle, the noise ceases, and this lead me to believe it may be the gears, but I'm really not sure. I've check the oil in the gearbox and it's fine. The noise doesnt seem to be affecting the way the car runs at all - it still accelerates fine, just with a weird noise. if anyone can help it would be greatly appreciated

[Simon P]

Have you checked the diff oil?
A dry worn diff will whine under load...

[bmcecosse]

Fan belt slipping? Generator bearings ? Try with the fan belt off for a quick run. Otherwise - clutch slipping? Is there 1" free play at the pedal?