BMW M5 CS

Revised connecting rod design compared to S63TU with 8 additional oil drillings. Despite this, documented failures exist: a workshop case study shows an F90 M5 with connecting rod and crankshaft damage. The F90 sees the problem less often than the F10.

Symptoms: Noticeable knocking from the engine, metal particles in the sump and filter housing, crankshaft damage as a consequence of delayed diagnosis

The high-pressure fuel pump can fail at high mileages or with aggressive use. Fuel pressure drop causes noticeable power loss and can secondarily damage injectors and turbochargers.

Symptoms: Power loss under high load, hard starting, fault code fuel pressure too low (P0087), stumbling at full throttle.

The turbochargers mounted in the V-valley are subjected to extreme radiant heat. Coolant lines and connections can crack through thermal cycling. Allow an adequate cool-down phase after full-load driving.

Symptoms: Coolant loss in the turbo area, coolant smell after driving, steam from the bonnet, reduced boost pressure.

Electric wastegate actuators on both turbo banks can fail — bank 2 more often. BMW has issued a warranty extension to 15 years/150,000 miles. Cost: €800–€3,500.

Symptoms: Engine fault message, power loss, limp mode activation, boost pressure regulation fault code (typically 4506E/4506F), drivetrain warning in instrument cluster

VANOS solenoids can generate fault codes despite the revised design. The S63T4 uses four solenoids — oil deposits are a common cause. Cleaning or replacement usually resolves the issue. The VANOS gear is a secondary cause if solenoid replacement does not help.

Symptoms: MIL activation, limp mode, fluctuating engine output, rough running at certain rev ranges

Same mechanism as on the S63: V-valley heat hardens valve stem seals. Workshop service £3,540–£4,140 with genuine parts (GND Motors). Typically appears from 120,000+ km.

Symptoms: Blue smoke on acceleration after an idle period, measurably increased oil consumption, sooty spark plugs

The S63B44T4 places heavy demands on the ignition system through high boost pressure and temperatures. A single failed coil signals further failures — standard practice is preventive replacement of all 8 coils at once.

Symptoms: Misfires, rough idle, power loss, fault codes P0300–P0308, noticeable vibration under acceleration.

The S63B44T4 generates extreme heat in the V-valley. Thermostat and plastic expansion tank are prone to premature wear at higher mileages. The overheating risk on failure is considerable.

Symptoms: Coolant loss without visible leak, temperature gauge fluctuates or rises too high, coolant level warning, steam from engine bay.

The xDrive transfer case requires regular fluid changes that BMW does not list as a mandatory service interval. Incorrect factory fill was known on related models.

BMW recalled several F90 model years due to possible failure of the low-pressure fuel pump. Engine can stall at startup or while driving.

Loose bolts on the front subframe cause clacking from the front axle. Retorquing the subframe bolts resolves the problem.

Adaptive dampers can lose oil or generate faults through wiring defects. System then locks into the hardest setting. Increased wear with track day use.

Optional carbon ceramic brake discs tend to grinding noises through pore contamination. Fine cracks are normal; deeper cracks require replacement. Salt in winter attacks the ceramic surface.