edwardsryan

Need some help I have recently purchased 2012 S550, It had a ticking sound that I thought and the pre-purchase inspection thought was a timing chain, however the vehicle has now been in the shop for a month, the timing chain did not fix the problem, apparently the tone rings on the M278 camshaft can become loose and throw off timing to the whole engine,I am told of the 4 camshafts in the engine 2 of the rings are bad. any ideas, they said they pinned the tone ring in the right position stated the engine up ticking sound went away and in about 10 minutes everything lossend up and the ticking sound came back. well over a month in the shop, mechanic has indicated he is working on his dime at this point to figure the problem out.