2005-2010, 2012-2019 BMW M6 Problems: 6 Known Issues

On the S85 5.0L V10 (E63/E64 M6), the VANOS variable-valve-timing system runs off a dedicated high-pressure oil pump mounted in the oil pan that works at up to roughly 115 bar (about 1,670 psi). Over time the pump's internal seals wear and the high-pressure VANOS lines can split, causing pressure to drop dramatically. The pump can eventually disintegrate, contaminating the engine with debris. This is a distinct failure from rod-bearing wear and is one of the most expensive non-bearing repairs on the V10. Left unaddressed it can cause valvetrain and broader engine damage.

The S85 5.0L V10 in the E63 M6 is known for connecting rod bearing wear. An engine reference says the oil clearance on engines built from 2007 to October 2008 with 088/089 bearings is smaller than engine builders generally recommend. With less clearance the bearings get too little oil, so they wear early. BMW later switched to 702/703 bearings with more clearance. Specialists add that heat cycles, cold starts, oil breakdown, hard driving and poor maintenance all speed up the wear. They also say maintenance history matters more than mileage, and some low-mileage engines show worse wear than higher-mileage ones. A worn bearing can spin, and that can ruin the engine. Warning signs include knocking from the bottom end, low oil pressure or an oil pressure warning, metal in the oil, and rising bearing metals (copper, lead, tin) in an oil analysis. Specialists treat bearing replacement as preventive maintenance on this engine, and one suggests doing it at roughly 50,000 to 70,000 miles on the S85.

The S63 4.4L twin-turbo V8 engine in the F06/F12/F13 M6 (2013-2018) has rod bearing concerns similar to but less catastrophic than the S85 V10. While the S63 bearing clearances are better than the notoriously tight S85, bearings can still wear prematurely under hard driving or track use, especially at high mileage. Bearing wear is accelerated by BMW's recommended 10,000-mile oil change intervals (too long for this engine). Preventive rod bearing replacement is recommended at 60,000-80,000 miles for peace of mind, particularly for cars that see track days or spirited driving. Oil changes every 5,000-7,500 miles are mandatory to extend bearing life.

On the E63/E64 6 Series and M6, owners report knocking and developing play from the steering gear (Lenkgetriebe); Active Steering was not available on the M6, which uses a Servotronic power-assisted steering system. German forums (motor-talk.de) describe a clacking/knocking noise and light play in the steering, with replacement steering gears quoted at well over 3,000 euros plus installation. Alongside the steering gear, the front control-arm bushings and other rubber suspension bearings wear out around 150,000-200,000 km, contributing to clunks and loose steering feel.

The S85 V10 engine in the E63 M6 (2006-2010) uses individual throttle bodies with internal throttle actuators containing plastic PPA (polyphthalamide) gears that strip over time, typically around 70,000 miles. The plastic gear teeth are gradually worn down by the metal worm drive, causing the throttle body to lose position control. When the gears strip, the affected bank of cylinders loses throttle control, causing limp mode, rough running, and diagnostic codes 2B15 or 2B16 (throttle actuator faults). The S85 has 2 throttle actuators (one per bank of 5 cylinders) - both should be rebuilt at the same time. Beisan Systems sintered metal replacement gears are the permanent fix - they outlast the plastic OEM gears indefinitely. This is a well-documented issue on M5Board and Bimmerpost.

The S63/N63 V8 family used in the F12/F13 M6 is subject to high-pressure fuel pump (HPFP) and direct-injector problems. A failing HPFP causes long cranking and hard starting (worst when cold), rough running and misfires from insufficient rail pressure. Separately, the direct injectors can develop internal leaks, dumping excess fuel and causing cold-start rough running, misfires and a Service Engine light. BMW issued a service bulletin for N63/S63 engines in F12/F13 addressing rough cold-start running with illuminated service lights traced to internal high-pressure injector failure; injectors must be matched to the correct index per bank.