MERCEDES: DUE TO LEFT AND RIGHT SECONDARY CHAIN TENSIONERS, OF THE CHECK VALVE, BEING INSTALLED AND PRESSED DEEPLY INTO CYLINDER HEADS, THE OIL SUPPLY CAN NOT BE ENSURED FOR CYLINDER HEAD, AND CHECK VALVE, OF LEFT AND RIGHT SECONDARY CHAIN TENSIONERS, MUST BE REMOVED. MODELS 2013 207(E350, 550), 212 (E350, 550, 63), 218 (CLS550, 63), 221(S550, 600, 65, 63, 400, 450, 350), 231 (SL). *PE