Hello all , great site ,have a question regarding my 97 e420 , have a noise coming from front of motor drivers side behind the belt tension er as near as I can tell,not at the bottom or the top mid level checked lifters they looked good, oil tubes are good ,no cracks or clogs took car to local MB guru or that what it said on his business card (40 years exp ) told me it was timing chain had my doubts , but hey who I am to argue with a guru , anyway 1 k later ,(new chain ) same noise,any hints here ? car has 211k , well looked after , the guru now says its piston slap , and if it is , anyway to check , as in pulling wire going to that plug and starting car or what, sorry for long post , thanks in advance.