There are 2 areas that can produce such noises and one of them is the tensioner.
The other would be the alternator bearing, if a one way clutch is used for the alternator.
March, 24, 2012 AT 4:04 PM
Thanks for your quick reply.
I'd like to add that the car is a right hand drive (Australia) and that the technician has looked at the tension of the belt and found it to be fine. Should I still ask them to take a look at the tensioner? To be fair to the technician, the sound is only intermittent and hence they probably could not identify the sound.
Is there any way they could identify the problem whilst the sound is not being produced?
Thanks once again
March, 24, 2012 AT 4:22 PM
If the noise is not present, it would not be possible for them to find the source of the noise.
When noise occurs, note the tensioner movement. Try turning on and off the A/C to see if there are any changes in the noise.
To test if it is from the alternator, stand by vehicle with hood opened and get someone to turn the engine off. If the noise tapers off after the engine has stopped, it would be the clutch bearing of the alternator pulley.
March, 24, 2012 AT 4:30 PM
I've already tried the A/C. No difference.
I'm leaning towards the alternator pulley bearing. Thanks for your help.
Do you think the technician would be able to take the bearing out and diagnose the problem on its own?
March, 24, 2012 AT 4:44 PM
Remove the serpentine belt and try turning the bearing and checking it for side movements.
On vehicle might be a little difficult to test for abnormal noises but if the alternator is out of vehicle, it would be easier to do so.
A stethoscope might help to locate the source.
When noise occurs, try splashing some water onto the serpentine belt and note if noise changes. If yeas, it would not be the alternator bearing.
October, 28, 2014 AT 1:08 PM
I would agree KHLow, the only difference I would suggest leave the belt on and use the stethoscope to find the noise, With the engine running be vary careful of moving parts. They are rather cheap and you should be able to pinpoint the noise