This may actually be a small red fish!

The Grunting/Hunting stops afer about 4-5 minuits running. This happens every time the engine is started (Hot or cold) so it might actually be something that is meant to occur.

Of course only somebody doing a service is likly to start an engine and not drive away so naturally the owner never noticed it before I commented on it (Should have kept my big mouth shut! )

Anyway. everything else seems fine now so unless anybody has any better offers I am going to assume that this is normal behaviour.