Ok well I spent alot of time again on the weekend and checked the following:
- Wheel bearing visual inspection only as it is a sealed unit. removed ABS sensor and all grease is fine, no metal particles and bearing makes NO noise when rotated (if it was going I would suspect it would make a noise at any speed)
- All gaskets inclduing inlet and exhaust, no leaks.
-Alternator bearing, no noise at any RPM or load,
- Uni joints, no noise bugger all play...
- As for valve spring then it would be there at various revs, also note that new springs were put into place when the engine was rebuilt 2,000km's ago...
the last thing I am going to look at is the brakes and whether the pads are moving around at all in the caliper...ran out of time to check this...