The 2017 S63 AMG with the M157 5.5L twin-turbo V8 is a high-performance luxury sedan plagued by catastrophic engine failures stemming from defective cylinder bore liners that crack under heat and stress. When these engines let go, they usually require complete rebuilds or replacements, making this one of the most expensive maintenance nightmares in the modern Mercedes lineup.
Cylinder Bore Liner Cracking / Engine Failure (M157)
Common · high severityTypical onset: 40,000-80,000 mi
Symptoms: Persistent coolant loss with no external leaks, White smoke from exhaust on cold starts, Rough idle and misfires across multiple cylinders, Coolant contamination in oil (milky appearance on dipstick), Check engine light with cylinder misfire codes
Fix: The M157 uses Nikasil-coated aluminum bore liners that crack under thermal cycling, allowing coolant into combustion chambers. Requires complete engine rebuild with updated liners or short block replacement. 40-60 hours labor. Some owners opt for used engine swaps to cut costs, but risk inheriting same defect.
Estimated cost: $18,000-35,000
Twin Turbocharger Failure
Occasional · high severityTypical onset: 60,000-100,000 mi
Symptoms: Loss of boost pressure and dramatic power reduction, Loud whistling or grinding noise from engine bay, Blue smoke on acceleration from oil burning, Excessive oil consumption (1+ quart per 1000 miles), Rattling noise at idle that increases with RPM
Fix: Turbo bearing failure is common, especially if oil changes were delayed. Both turbos are typically replaced together to prevent comebacks. Requires removing subframe and extensive disassembly. 16-20 hours labor. OEM turbos only—aftermarket units fail quickly on these high-output applications.
Estimated cost: $8,000-12,000
7-Speed MCT Transmission Oil Cooler Leaks
Common · medium severityTypical onset: 50,000-90,000 mi
Symptoms: Transmission fluid puddles under vehicle (red fluid), Low transmission fluid warning on dash, Harsh or delayed shifting when cold, Burning smell after highway driving, Transmission slipping under hard acceleration
Fix: The external transmission oil cooler develops leaks at crimp points and seams. Requires cooler replacement plus fresh fluid and filter. If driven low on fluid, internal clutch damage occurs requiring full trans rebuild. Catch it early. 4-6 hours labor.
Estimated cost: $1,200-2,000
Airmatic Suspension Strut Leaks
Common · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Vehicle sitting noticeably lower on one corner overnight, Suspension warning light and 'car too low' message, Compressor running excessively (audible humming), Rough ride quality over bumps, Uneven tire wear on affected corner
Fix: Air struts develop leaks at rubber bellows and internal seals. Typically fail one at a time but best practice is replacing in pairs per axle. Requires STAR diagnostic system to calibrate after replacement. 3-4 hours per strut.
Estimated cost: $2,500-4,000
Transmission Mounts Collapsing
Occasional · low severityTypical onset: 50,000-80,000 mi
Symptoms: Clunk or thud when shifting from Park to Drive/Reverse, Vibration at idle that disappears when in Neutral, Excessive driveline movement visible during hard acceleration, Rubbing or knocking sounds over bumps
Fix: The high torque output destroys rubber transmission mounts faster than normal. Front and rear mounts typically need replacement together. Requires lifting transmission slightly. 3-4 hours labor.
Estimated cost: $800-1,400
Magic Body Control Front Camera Failures
Occasional · low severitySymptoms: Magic Body Control suspended message on dash, Camera view blank or distorted in display, System defaults to standard suspension mode, Intermittent loss of road-scanning function
Fix: The stereo camera behind windshield for road scanning fails due to moisture intrusion or internal circuit failure. Requires camera replacement and recalibration. Does not affect basic Airmatic operation, only predictive suspension adjustment. 2-3 hours labor.
Estimated cost: $2,000-3,500
Only buy if you can afford a $25k engine rebuild or have access to a comprehensive warranty—this platform's catastrophic M157 failures make it a financial landmine for the average used buyer.
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.