Odd Noise When Cold 2500+rpm (vid)
 

As it's been getting colder, I've noticed that right after start up, anywhere above 2500 or so RPMs I get a strange noise, kind of a cross between a whirring and a screeching. Once the engine is warm, no more noise. If it is warm out, the noise is much less pronounced. It will make the noise just revving in Park as well. This is a 2008 4.4 HSE with 91K miles.

Any ideas what this could be? It's worst around 0:06 and 0:24 as the revs get at/above 2500.

I listened and couldn't really hear anything. Squealing noise at a certain RPM level makes me think that it could be the serpentine belt though.

Can't really hear it either. Suggest turning off the HVAC and trying again. If it is happening or worse when turning the wheel, check your Power Steering fluid, and belts as previously mentioned. The belts are due if I recall at 95k. I suggest also changing the tensioners.

It's definitely not a belt slipping squeal (familiar with that). It's such a strange noise, it's hard to put into words. Definitely from something rotating and dependent on RPMs. It seems to originate from the passenger side of the engine compartment. I'll try to get a better video of it.

When cold mine sounds different until the thermostat opens. maybe the water pump working harder?

Tried to get another video. This morning it wasn't as cold so it wasn't as pronounced, but you can still hear it.

I dont hear anything serious. It could be anything thats belt driven. I wouldn't worry about it until something breaks. If you wanted insurance buy a spare belt, alternator, and tensioner and then they will never break on you. Get a snow blower too and then no more snow :-)

New pulleys etc perhaps?
 

I have about 150,000 miles on my 2005 LR3.

I recently put all new idler pulleys/bearings and tensioner pulley plus two new belts. I however did hear a sort of squeeking at idle and independent of engine temperature from the 'front" somewhere when standing outside by the front bumper.

To my pleasant surprise, my engine quieted down. It now sounds new - that is all the whirring noises that I had got used to that I regarded as just old age went away and when outside by the truck, one does not hear much in the way of noise at idle any longer. From inside, at idle, I have to look at the tach to see if the engine is running.

In your case, there may be one that is wearing early or it could be something to do with the engine cooling fan staying engaged, but I do not hear that.