Re: B18b1 Fluttering noise ?!
check oil levels? after the "pop" sound it made did you feel a loss in power? whats the oil look like?
slightly bent rod? if you rev it up high does it sound like a hard slapping noise?
not sure by what a flapping noise is.. just check for signs of headgasket, bent connecting rod, and the oil light goes on and off check oil level maybe ur pump isnt pumping oil correctly?