Hi guys I’ve had a engine rattle or knock when my engines cold and you put your foot down. Almost goes away when warm but you can still hear it. Anyway took it the garage and they’ve replaced the water pump a pulley and the tensioner with a new belt for the price of £540. The noise is still there and the garage are now saying it’s the cam chain and want £750 to do it. So thought I’d get a second option and got my cousin down who’s a bmw mechanic for 25 years. He says it’s not the chain and sounds like a bottom bearing or cam bearing. My heads shot over it and would appreciate any advice thanks.