Chain tensioner doesnt do much. Dealer is Williams in Manchester, Ive found them very good and extremly helpful in deed. I suppose you have to let the dealers go through the motions, new tensioner, new cam lifters then like i did, keep taking it back, take recording on your phone, play them to your dealer, stress a modern engine should not be sounding like this ask them to go back to BMW for further assistance. Everything has to be carried out to BMW instructions for the dealers to put the warrenty claim in i think. BMW tech rep said they have seen the problem before and it orignates from the cyinder head, valves and variable timing. I had two options either to re build the cylinder head to incorporate the modificatiosns of the new wngines which include new valves, timing chain, cams lifters or other option replace the engine with the modified cylinder head. Apparently its the early
MCS that are giving the problems.