The F90 M5's S63TU engine is a high-strung twin-turbo V8 that delivers incredible performance but has a documented history of rod bearing wear and cooling system stress under sustained high load. The 8-speed ZF transmission is generally stout, but its cooling and mount hardware need attention as miles accumulate.
Rod Bearing Wear / Spun Bearings (S63TU)
Occasional · high severityTypical onset: 40,000-80,000 mi
Symptoms: metallic knocking at idle or under load, low oil pressure warning, metal debris in oil filter during analysis, catastrophic engine failure if ignored
Fix: Preventive service is 12-16 hours for rod bearing replacement with crank polishing. Full engine rebuild after spun bearing runs 60-80 hours including machine work, new pistons, rings, bearings, gaskets, and reassembly. Many owners do bearings preemptively at 50k-60k miles on track-driven cars.
Estimated cost: $6,000-9,000 preventive bearings; $25,000-35,000+ full rebuild
Transmission Oil Cooler Leaks
Common · medium severityTypical onset: 60,000-100,000 mi
Symptoms: transmission fluid puddles under car, low trans fluid warning, burnt trans fluid smell, harsh or delayed shifts if fluid level drops
Fix: Cooler lines and main cooler assembly develop leaks at fittings or through corrosion. Replacement involves lowering subframe or transmission for access, 4-6 hours labor plus fluid refill and programming.
Estimated cost: $1,200-2,200
Transmission Mount Deterioration
Common · low severityTypical onset: 50,000-90,000 mi
Symptoms: clunking on hard acceleration or deceleration, vibration at idle in drive, excessive driveline movement felt through chassis, visible cracking or separation in rubber mount
Fix: High torque output accelerates mount wear. Replacement requires transmission support and subframe access, 3-4 hours per mount. Front and rear mounts often fail together.
Estimated cost: $800-1,400 both mounts
Fuel System Carbon Buildup (Direct Injection)
Common · medium severityTypical onset: 40,000-70,000 mi
Symptoms: rough idle and misfires, reduced power and throttle response, check engine light with misfire codes (P0300-P0308), fuel trims out of spec
Fix: S63TU uses direct injection only, so intake valves get heavy carbon deposits. Walnut blasting both cylinder heads requires intake manifold removal, 6-8 hours labor. Some shops pair this with spark plug replacement.
Estimated cost: $1,200-1,800
Coolant System Leaks (Turbo Coolant Lines & Expansion Tank)
Occasional · high severityTypical onset: 50,000-90,000 mi
Symptoms: coolant loss with no visible external leak, low coolant warning, steam from engine bay, overheating under sustained load, coolant smell in cabin
Fix: Turbo coolant feed and return lines crack at fittings or develop pinhole leaks. Expansion tank can crack at seams. Access requires bumper removal and working around hot-side turbo hardware, 4-6 hours depending on line location.
Estimated cost: $1,000-2,000
High-Pressure Fuel Pump Failure
Occasional · high severityTypical onset: 60,000-100,000 mi
Symptoms: no start or long crank, limp mode with reduced power, fuel pressure fault codes (P0087, P0088), rough running under load
Fix: HPFP on the S63TU sits in the valley and requires intake manifold removal for access. Replacement is 5-7 hours including fuel system depressurization and priming.
Estimated cost: $2,000-3,200
Buy only with full service records and oil analysis history, or budget $10k-15k in deferred maintenance—the performance is addictive, but the S63TU demands respect and preventive care.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.