56 Focus (1.4 Sport) Engine whine/whirring/wobbling at lower gears?

[Reliance]

Hi folks, I'll try to explain the issues I've been experiencing lately, in the hope someone can give me a little advice. I haven't had the chance yet to fully investigate due to a lack of free time, but I will be doing so soon, hopefully with some pointers from you good folks.

 

In the last couple of weeks I've noticed my car makes a weird sort of whine/whirring noise from the engine bay in lower gears, usually 1st and 2nd. Once upto speed I don't hear it so much. At first I assumed it was something to do with the actual engine. It doesn't do it when idleing, but when I accelerate. It doesn't do it too bad until the engine has warmed up. Last weekend I had a quick look under the bonnet, and only thing I could see that was off, a few screws on my air filter box had worked themselves loose. I tightened them and they made no difference, if anything the noise has gotten louder since then. 

 

It's hard to described the sound, I've just noticed it and it has gotten louder over time. It does not affect the cars performance in any way as far as I'm aware. Although, I was driving in the valleys in Lancashire earlier this week and the car struggled SO bad getting upto speed while driving up hills. This could just be me being paranoid, but along with that noise I was cacking my kecks incase something blew out there in the sticks. 

 

Also, when parked on a hill earlier this week, I gave the engine a few revs and the noise sounded like it may have been coming from underneath the car or even out of the exhaust? This obviously made me think it could be an exhaust blow, as sometimes it does sound like a whine or a slight whistling/whirring noise. But most often I heard it coming from in front of me when driving, maybe towards the left or centre of the engine bay?

 

Any ideas would be greatly appreciated, or if anyone has experienced similar? I will be hopefully having a proper look to try get a better idea of what is the cause this weekend, and thereafter will be likely taking it in to a garage if it's something I can't fix myself. Car has 98k miles, and has had cambelt done in past 8 months and also the sparkplugs done, had an oil and filter change in Feb, changed air filter around the same time, all levels are as they should be, etc. 

[ashmicro]

Timing belt cover loose/not put back on properly? Long shot, but I've seen it happen, and the pulleys and/or belt rubbing on the cover makes a hell of a racket.