well we got ideas,thats a start,just seem strange to me that the problem comes at start up,just thinking,could the motor oil be leaking from the check valve at the filter back thru the oil pump and the pump loses prime and then the chain gets loose from lack of oil presure for that instant the oil pump builds pressure back? one good test would be to let one sit, check the oil level and see if the level rises.
steve on the 5 year cycle that you recommend,do you change the tensioner also?
larry perkins lou ky