I haven't been on the forums in a while, but this thread is highly relevant to my vehicle.
My '09 CE 1.8L auto has 141,000km or 87600 miles on it. I am diligent about letting it come off fast idle before driving when started cold, keeping it under 3000rpm until warmed up, smooth on the throttle to make life easy for the tranny etc etc. That said, the car has been put through it's paces. There is NO carbon in that motor, guaranteed. Plenty of WOT in it's lifetime.
I replaced the water pump at just under 100,000km (62k miles), if I recall correctly. I don't have sound on my work computer, but I assume it's the same metallic "scape/light rattle" that my car made before replacing the pump. I am not surprised at all about the one dealer doing 7 water pumps already. No sounds or failure from the new pump after over 40,000km.
Since about 60,000km (37k miles) or so, my car "purrs" at idle, when warm. No, I'm not talking about it running well, it's always done that. When idling in park/neutral OR drive, a soft rattle oscillates (think sine wave pattern) at the rate of about 1.5 seconds between peaks, coming from the back (firewall side) of the cylinder head. It's not loud, but noticeable from the cabin. It has been suggested to me that the VVTi actuators could be causing this, and that it could be proven by using a code reader that can display diagnostic info to view the cam angle data and see if the rattle coincides with change in the angle. I didn't think the VVTi would be modulating cam angle at a constant RPM, but I don't know the workings of the system very well. This sound has been occuring at the same rate/intensity ever since, and has not seemed to affect the operation of the motor whatsoever. It does not run poorly at idle, and has the same response/power as new, if not a bit MORE power than when it was new.
One of these days I will hook up a code reader that can pull cam angle data and actually see if it is a VVTi solenoid. Perhaps it's worth a seperate thread?