To cut a long story short, I've had a knocking noise for a while now from the underside of the engine and on inspection it seems to be my coolant pipe that's loose ad hitting my downpipe, I've tie wrapped it, wrapped It in rubber and yet I still get the knocking noise however the noise is particularly worse when I'm reversing. It seems The noise gets worse as the car finds the biting point and the odd occasion ill hear the noise when going down the gears ie slowing for a roundabout or steep hill