I don't know why dipping the clutch would make it stop either!
Apparently there is a bracket that holds the lines, that has to be taken off to change the oil filter. (At least i know they changed that!)
It can, quite easily apparently be fitted back incorrectly, causing the routing to be wrong, and it 'can' cause a kink to develop in the line.
This is what had happened. My dealer says that they do see it from time to time (Apprentice/trainee, will usually get the oil change job!)
It may be total B.S from my dealer, or it could be the truth.
Bottom line- Got it back last night, and NO noise at all, and it drives sweeter than ever. Mind you, that could be because Ive been driving around in a Renault van for three days!