M156 engines produced between the years of 2007-2011 are prone to premature camshaft and valve lifter bucket failure. Customers will describe a loud ticking or top-end knocking noise from either the left or right bank cylinder head. The issue has been pinpointed to sub-grade cast nodular iron camshaft material and 9310-grade steel valve lifter buckets. The repair involves replacing all the four camshafts with the latest updated part from Mercedes Benz, additionally upgraded SLS valve buckets are recommended with this service.
The service involves, draining the oil, removing both valve covers, removing both camshaft actuator solenoid assemblies, installation of specialty M156 camshaft timing tools, installation of cam adjuster locking tools, and removal of camshaft adjusters. At this point, the camshafts can be removed and valve buckets can be inspected and replaced if required. If your M156 engine has not had the head bolts replaced with the latest updated external Torx head bolt from Mercedes or the recommend ARP stud update, we would recommend you perform this service at this point. Once the engine is reassembled and new oil is added, the engine is ready to start. The new buckets will need to time to pump up before the engine completely quiets down. This can take many minutes to many hours. Multiple test drives are performed to ensure all lifter noise has dissipated and the engine sounds quiet. We typically recommend an immediate oil change after the camshaft break-in procedure is complete.
If you have any questions or are in need of a similar service yourself, just send us a note or give us a call.