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A few seconds after starting the car in the mornings there is a whirring/squealing noise. It happens for about 60 seconds then stops. As it cuts off it sounds like a motor 'slowing' down.

I recently swapped the thermostat but all seems good after bleeding and driving round a bit, no overheating etc. So don't think its connected with that.

I have a recording but don't know whether it can be attached to a post here. I have recorded it on a video on my phone.

As the noise happens for a minute then shuts off it lead me to thinking that it is suspension related.

I haven't had any suspension warnings come up on the message centre. The car doesn't look down on any corners. Do I have a small leak in an airspring (which isn't bad enough to generate a fault code) which the compressor is trying to sort out when I start the engine? I have heard problems with air suspension can show up in colder weather.

Is there anything else on the car that would cause a similar noise on startup? I could just ignore it and if it is suspension related then maybe if the air leak gets bad enough a code will be generated?

A 'squealing' type noise can be caused by lots of items including a slipping serpentine belt (that drives the water pump, alternator, power steering). It could also be the idler pulley bearings (that tensions the serpentine belt) the water pump bearings themselves, or the power steering pump. You need to try and pin point the source with the bonnet up when you have started the car.

I have managed to get the audio off the video I mentioned. I dont think mp3s are allowed. So heres a link:

https://www.filehosting.org/file/detail ... _0296a.mp3

Anyone got any thoughts on what it sounds like.

A 'squealing' type noise can be caused by lots of items including a slipping serpentine belt (that drives the water pump, alternator, power steering). It could also be the idler pulley bearings (that tensions the serpentine belt) the water pump bearings themselves, or the power steering pump. You need to try and pin point the source with the bonnet up when you have started the car.

There is a slight squeak squeak which you can hear after the whirring stops which I think is caused by what you refer to. But I think this noise has to be something else as it only happens when you first start for about a minute then its gone.

That sounds like bearings; belt tensioner / idler pulleys, alternator, PAS pump, water pump would be good places to start looking. Mine made similar, but much less severe noises from cold, prior to replacing the pulleys and water pump last year.

I have one slightly noisy idler bearing on the front of my 04XJR. Its not helped by having a super-small supercharger pulley running on 100k bearings.

Drive belts can also get noisy as mileage increases. Its also worth noting that the sprung idler tensioners units can make a very loud clattering sound when ice and snow hit us. They can freeze up and make a heck of a racket until they thaw out. Cars kept in the open are most likely to be affected...tell me about it!

PAS pumps can also become slightly vocal at higher mileages. Then there is the alternator to consider which obviously has bearings that can wear. The metal bladed, later 4.2 litre water pump can also be fitted to the earlier 4 litre V8 models. That pump is far more robust than the original 4litre V8 unit fitted with the disintegrating or slipping plastic impeller and weak bearings. New after market water pumps can be found on eBay for around £40. I have a spare kept in my sock draw for easy access just in case I need it!

Mike

I've not been able to listen to your mp3 file.

However, a squealing sound would typically be caused by a loose/worn drive belt and often only lasts a short while due to the alternator being heavily loaded replacing the charge in the battery following starting the engine. If the belt is really loose/worn, the squeal will often sound when accelerating the car/alternator or otherwise increasing the load on the belt maybe by turning the steering wheel whilst stationary and on tickover only - as I have now on my Subaru. I just tightened the belt a bit so I will see later if it's cured, else it will be a new belt needed.

Worn bearings typically produce the whirring or more likely growling/grinding noise. This can easily be located with the help of a long screwdriver or similar. Press the tip onto suspected components (alternator, water pump, power steering pump) and press your ear to the other end. You will soon locate the source of a worn bearing noise. Obviously you need the engine running for this so take care not to get anything caught in any drive belt.

HTH. Jerry