oh, forgot to add its an auto box, which seems to work just fine through the gears, kickdown etc
Sounds like a diff on it's way out.
Sounds favourite but it might be a bearing on the transfer box.
You maybe correct, but usually the bearing would make a noise on the overrun and be less noticable with power on. Unlike a diff which makes a noise under load but usually goes quieter on the overrun. The driven face of the crown wheel usually gets pitted as does the pinion this causes the noise under load. When the pinion is driving the crownwheel. Whereas on the overrun the crown wheel is driving the pinion with it's unworn surface in contact with the unworn face of the pinion.
Makes sense to me! I did wonder if maybe a worn pinion bearing could be a suspect but I've never heard one so am guessing.
Worn pinion bearings usually show more on the over run as you are slowing, as sounding like something winding down. Not as noticeable power on but still there all the same. Power on they sound like a wheel bearing with a slightly changing note, on the overrun they sound like a spin drier slowing down.
thanks for the replies, worn out diff was what i was thinking =/ unless it really really starts to **** me off i may just run it til it goes and then replace it. weve got a toyota van at work thats had a really noisy diff for the last year or so that is still going and doesnt seem to have got much worse.
any way of telling whether its coming from front or rear, other than just having a listen and trying to guess?