hum from the rear

[cortina]

i am getting a slight hum from the rear (nothing personal)If you twitch the steering to the left it ceases.,then hums again when in straight line.diff?wheel bearing?

[kam-325i]

I would have a guess at the Diff, might need an oil change.

[stuartgallafant]

sounds like a wheel bearing, although the diff is also a possibility as you say it goes when you turn left

however, throwing the steering to the left will take the load off the left rear wheel slightly, and it will make it rotate slightly slower than the right wheel. thats why the hum will go away

the best thing to do is...

-get the rear end in the air (use a ramp ideally, or 2/4 axle stands)
-put the car in 2nd gear and take up to around 40mph
-ask your assistant (not the missus!!) to listen, firstly to the centre of the wheel, and secondly to the diff, to try and locate where the humming is from
-you may find it better to listen yourself and ask someone else to sit in the car???
-stop the wheels, and grab the wheels at a 3 0clock and 9 oclock position and rock the wheel, then do the same at a 12 oclock and 6 oclock position - if there is any free play in the hubs, then this will indicate a knackered wheel bearing

hope this help pal....