The engine runs fine and pulls ok. Its just on start up for a spli second you get a clacking rattling sound which sounds terminal and then goes. Also, it comes back again once you switch the engine off and let it rest for say 15 mins. This time though its more of a tapping sound which disappears when you blip the throttle. It could be tappets but I dont think you would get that extreme clacking sound on start up for a split second.
God knows.
God knows.