[Thekilt]

Originally Posted by RS3100

I believe the part that you have circled is the brake system vacuum pump. However, the part just to the left of your red circle with the steel pipe running up to the fuel rail is the high pressure fuel pump, which is mounted onto the vacuum pump casing.

These engines are direct injection engines which feed petrol directly to the cylinders through individual injectors in a similar way to diesel injection systems. The system operates at high pressures and what you can hear may be the fuel pump resonating through the vacuum pump housing.

Mine has an obvious tapping sound very similar to diesel clatter, although less intrusive, for less than a minute when started from cold, but apart from that I can't say that I find it at all noisy.

Are you talking about a tapping or clattering sound, or is it something else?

Some engines have been know to develop a whistle or whine that changes tone with the engine revs and is attributed to the balance shaft bearings. A modified balance shaft module has been introduced to overcome this.

Thanks for this. After a bit more googling i discovered these are GDi engines which as you said utilise higher pressures for direct injection. I found Delphi have been working on a higher pressure system and reducing noise. Also quite a few papers written on this subject and how to avoid it. Interesting reading but unfortunately it seems that its nothing that can be changed to help it.
I will check the car on friday after it has heated up, see if that changes the sound.