The 2022 S63 AMG with the M177 4.0L twin-turbo V8 hybrid is still relatively new, but early patterns show troubling engine reliability issues reminiscent of older AMG bearing failures, plus transmission cooling concerns that can cascade into expensive repairs if ignored.
Connecting Rod & Main Bearing Failure
Occasional · high severityTypical onset: 30,000-60,000 mi
Symptoms: Metallic knocking or ticking from lower engine, especially cold start, Oil pressure warning light or fluctuating oil pressure readings, Metal shavings in oil filter during changes, Sudden catastrophic engine failure in worst cases
Fix: This is the nightmare scenario. Requires full engine-out, short block replacement or complete rebuild with updated bearings. 40-60 hours labor plus $15,000-25,000 in parts depending on core damage. Some early failures covered under warranty, but post-warranty this is financially devastating.
Estimated cost: $25,000-40,000
Transmission Oil Cooler Leaks
Common · medium severityTypical onset: 40,000-70,000 mi
Symptoms: Transmission fluid puddles under vehicle, usually pink/red, Transmission temperature warnings on dash, Harsh or delayed shifting when fluid level drops, Sweet smell from engine bay
Fix: The 9-speed MCT transmission oil cooler develops leaks at connections or internal seals. Requires dropping subframe for proper access. 8-12 hours labor plus $800-1,200 for cooler assembly and fresh ATF. Catch it early before low fluid damages valve body.
Estimated cost: $2,200-3,800
Transmission Mount Deterioration
Common · low severityTypical onset: 50,000-80,000 mi
Symptoms: Clunking when shifting from Park to Drive/Reverse, Vibration through center console at idle in gear, Excessive driveline movement visible during hard acceleration, Rough engagement on throttle tip-in
Fix: The hydraulic transmission mount wears from the massive torque of the M177. Replacement is straightforward with proper lift access. 2-3 hours labor plus $400-600 for OE mount. Don't delay—a failed mount can stress the driveshaft and torque converter.
Estimated cost: $900-1,400
Turbocharger Wastegate Rattle
Occasional · medium severityTypical onset: 20,000-50,000 mi
Symptoms: Rattling noise from engine bay on cold start, disappears when warm, Turbo rattle audible during light acceleration around 1,500-2,500 RPM, Check engine light with underboost or overboost codes, Loss of power in extreme cases
Fix: Hot-vee mounted turbos develop wastegate actuator arm play or flapper wear. Turbos are sandwiched under intake manifold. Each turbo replacement is 12-16 hours labor plus $3,000-4,500 per turbo. Mercedes has issued updated turbos for some VINs—check for open campaigns.
Estimated cost: $6,000-9,500
Fuel Filter Clogging from Hybrid System Contamination
Occasional · medium severitySymptoms: Rough idle or stumbling during acceleration, Limp mode activation with fuel pressure fault codes, Hard starting after sitting overnight, Reduced power output
Fix: The hybrid's integrated starter-generator (ISG) shares engine oil, and metal contamination from early bearing wear can circulate and clog the high-pressure fuel filter. Filter replacement is 1.5-2 hours labor plus $150-250 for filter. If caught late, injectors may need cleaning or replacement adding $1,500-3,000.
Estimated cost: $400-800
48V Hybrid Battery and ISG Faults
Rare · medium severitySymptoms: Check engine light with hybrid system malfunction codes, Loss of EQ Boost function (no electric assist), Rough engine starts without ISG starter assistance, Battery warning messages on instrument cluster
Fix: The 48V mild hybrid system can develop ISG controller faults or battery cell degradation. Diagnosis requires Star Diagnostic tool. ISG replacement is 6-8 hours, 48V battery is 4-6 hours. Parts are expensive: ISG $4,000-6,000, battery $3,000-4,500. Most failures under 60k mi are warranty-covered.
Estimated cost: $5,000-10,000
Only buy with comprehensive warranty coverage through at least 80k miles—the M177 bearing lottery and hybrid complexity make this a financial gamble without protection.
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.