Noise

[davidjay]

This is a difficult one to describe, but here goes. 2.0 05 auto. About a week or so ago, a couple of times over the course of a few days I had a loud whistling/humming noise from the engine that lasted for a few seconds then stopped. After the second (or maybe third) time, it was replaced with a constant, quieter, noise of a similar pitch over the normal engine note. I've noticed no difference in performance or fuel consumption but naturally I'm worried that something is about to go wrong big style. Any ideas?

[Max Headroom]

Roger Whittaker is stuck in your engine bay? 

It's possible its a belt or a pulley bearing. Is it sequential or constant?

[Norfolk Jim]

Shouldn't be a prob on that engine but check your sump.

Don't want to worry you but mine made that noise about a month before turbo went!. What mileage are you at.

The noise I got was a high pitched whistle like a turbine (sounded great) but you shouldn't hear turbo at all unless its a hybrid.

Roger Whittaker - Trenchfoot - you'll be telling us you wear a Val Doonican sweater next!

[sgould]

Could be many things, including...

The whistling caused by a blocked sump oil strainer usually occurs only when the oil is cold and thick. It goes away when the oil heats and thins.

Could be an idler bearing.

Could be a split diaphragm in the turbo thingy.  Although I wouldnt expect that to go away. The check is to blow into the three pipes in turn, blocking off the others.  If you can blow through all combinations the diaphragm has split.

The other one I've heard of, but only experienced on another car, is a resonance in the oil filter.  The filter has a thin "paper" flap in it to prevent all the oil draining from the filter. Sometimes these can vibrate as the oil passes, a bit like the reed on a clarinet.

Could be a split pipe.

Oil and fluid levels OK?

Might be the vacuum pump on the brake circuit or the pipe to the servo.

[davidjay]

It's done around 75k miles and fluid levels seem okay. It's not a turbine-like sound (not that I'd be too sure what one sounded like) and it's pretty much constant when moving. 

[Norfolk Jim]

Not the turbo then as that's only under power.

Daft question - you've not got some leaves in the fan motor? I sometimes get it as we have 3 VERY large oak trees and occasionally some get in the housing and give a constant whirring noise. Only way to shift was make sure all vents open and full blast fan but keep switching locations around like screen then vents then floor then vents...........

Is it constant with car speed and or engine speed?

[sgould]

If the noise starts and stops with the ignition switch without starting, it can't be the engine.

Ignition will start all the fans, heater and cooling if the aircon is on and the outside temperature is high enough.

[Max Headroom]

Roger Whittaker - Trenchfoot - you'll be telling us you wear a Val Doonican sweater next!

You would be surprised at my wardrobe Jim 

[davidjay]

It seemed a bit quieter today; I couldn't really hear it above the usual engine noise after 30mph. It's more of a whine than a whistle - sorry to be so vague but thanks for the advice.

[Max Headroom]

Can you get it to happen at the same engine rpm but when you are stationary?
Could it be wind noise?  Pardon!

[sgould]

Could it be something that sounds like a front wheel bearing?  If so, check the wear on the inside edge of the rear tyres.

[davidjay]

And now, while moving the car a few yards it started before I drove off.

[JB]

I've got a 'funny' whining noise which I've tracked down to the aircon compressor. If I turn the aircon to econ the noise simply disappears. If I then turn the compressor back on then it usually takes a few seconds for the whining sound to build back up again. I think it's to do with the bearings on the compressor.

[sgould]

If it's the aircon, it could be a lack of refrigerant.