Hi, my 560SL has a cracked left valve cover. Searching the forum I see that it needs timing chain and guide replacement along with the tensioner. Does the cracked valve cover mean the car has bent valves or simply the guide broke and cracked the valve cover? The motor has not been running over 500rpm as there seems to be fuel issues. Just replaced the fuel pumps, filter, fuel accumulator and associated fuel lines in that cluster. Also just had Timevalve stainless exhaust installed hoping the sluggish engine was caused by plugged catalytic converters but no such luck. Do I have the timing chain and guides etc replaced or source a replacement engine? Thanks!