Can anyone shine a light on this possible problem I have?......sounds like a soft, almost melodic low pitched noise/whirr/whoo. Sometimes...sat in the car stationary, engine running, the sound will raise slightly in pitch that seems to coincide with the radiator fans kicking in and is there at all other times at low revs. Not heard higher up the rev range or at constant speed although it does seem speed dependent/alter pitch at low revs, ie: less than 2k RPM.

Doesn't appear to have anything to do with the steering which is light and quiet, doesn't alter in intensity/drop off when loading alternator or when turning fan/AC on/off and is not (as far as I can tell) related to the turbo...it has been like this for quite some time now and has no ill effects on the cars performance in general, it sounds just like a ghost trapped under the bonnet for want of a better description

Ay up Dunk,
When you say 'radiator fans', I think these may well be the aircon condenser fans and the noise is the compressor. Another member of the failed FL2 clutch/DMF club, twice.

Do you think? what would be the best way to pin this down? the noise doesn't seem to change pitch with aircon' activated or off.....the fans I was harping on about are the two big that sit directly behind the radiator.

As you can probably tell, I'm not overly technical....

How are you turning off the aircon?
Also, listen after a cold start. The cooling fan shouldn't be running normally Another member of the failed FL2 clutch/DMF club, twice.

Quite sure fans aren't running from cold, just happened to notice a while back whilst stopped in a field with the dogs, (sounds bad that)! had the bonnet up listening with engine running and noticed the pitch of the noise change when fans chimed in. Noise is there from cold or hot and as for how I turn AC on off?......................I can't remember , possibly by shutting ventilation/fan off completely while AC was on/running but I'm guessing, last time I tried it was weeks back.

Will have another play tomorrow and make a few mental notes

Dunk,
If the heater control is set to 'Auto', the aircon is on no matter what temp you set it to.
You need to set it to 'econ' or turn it off completely.
Let me know how you get on  Another member of the failed FL2 clutch/DMF club, twice.

Yes, I understand that me ol' mucker.....can't remember if I toggled the push switch to economy/off or turned dial that sets speed to off, heads gone

Either way will have another go and come back.

Right, Pegleg.......noise is there at start up, condenser fans not running, air con' off, stays at same pitch if air con is activated. Rev the engine slightly and the noise raises and lowers with engine revs. Only really heard up to 1.5k revs. Noise there at neutral or when in gear being driven at low revs, once on the move and higher up the rev range or in a higher gear the noise disappears.

I did notice earlier while in stationary traffic, the noise seemed to raise without me touching anything, did sound like the condenser fans had kicked in at the same time.

It's all rather strange, it's not really an annoying noise but it would be nice to know what it is....

Ay up Dunk!
Well, that's ruled out the condenser fan and compressor which I was hoping it was!
The only other thing it might be is the power steering pump. I can hear mine slightly as the impeller spins round. That noise goes up and down in proportion with rpm

Apart from that, I've not been much use
Failed. Sacked in the morning!
Sorry Dunk Another member of the failed FL2 clutch/DMF club, twice.

.........thanks for the help Pegleg, had a chuckle at that. Steering feels light, no undue noise on full lock, fluid reservoir not full of bubbles and fluid itself sort of grey in colour, not the dreaded black so if it is that it isn't showing any typical signs, the level is just above the 'low' line so maybe a top would help.

I will have to learn to live with being spooked at low revs until I find it.......I have been wondering if a pulley idler running dry or something like that may be the culprit?

Will keep at it and if I find the problem I will post it up

hi, did you ever find the ghost under bonnet noise?

Am having exactly the same noise you described and have been struggling to find the answer.

Thanks.