After buying a new waterpump and idlers, £134, I have found the noise to be the cam belt back plate...
The plate that sits behind the cam belt and the idlers etc.
It seems that when it gets warm, it starts to vibrate at a frequency that isn't affected by engine RPM. And it makes a helluva noise.
This started after I changed the gears in the oil pump so obviously I had to take the plate off to get the oil pump off but this was at least the third time the plate has been off. So why is it Vibrating??
I'm gonna put some silicon behind it or something tonight so that it stops the rattle but I'm interested in the cause not the fault. Any ideas??
Has this happened to anyone else??