Hi Alan

Thanks for your input, I think it is highly possible the Cam pulley keyway could be damaged.

Both sides of this engine need checking, the other garage will probably be stripping and investigating the Mazda with the evidence I can give them.

I always try to work out/guess what might have gone off to cause the problem (I am known to think to much)

For arguments sake, if the back of the inlet cam (above gearbox) got wedged up and the motion of the engine caused the timing belt to wrench the Cam pulley round the wedged inlet Cam, breaking the keyway and possibly tightening the Cam pulley bolt even more.

The Cam pulley would be fixed in an advanced position but the actual Cam and Cam sensor pickup would infact be retarded?

I know it is nearly impossible to predict what would happen in a catastrophic failiure like this but, this has just got my brain ticking as to how the inlet cam could advance when this is the component that has momentarily stopped moving/slowed down.

I will update the outcome
Thanks for any input/suggestions

James