The 2022 McLaren 720S with its M840T 4.0L twin-turbo V8 is a remarkable machine, but it's plagued by catastrophic engine failures tied to piston ring defects and cooling system issues that can destroy motors at shockingly low mileage. These are exotic supercars with exotic repair bills—plan accordingly.
Piston Ring Failure Leading to Complete Engine Rebuild
Occasional · high severityTypical onset: 15,000-40,000 mi
Symptoms: Excessive oil consumption (quart per 500-1000 miles), Blue smoke from exhaust on startup or under load, Loss of compression and misfires, Check engine light with lean/rich codes or misfire codes
Fix: Factory defect in piston ring gap tolerance causes bore scoring and loss of compression. Requires complete engine-out rebuild with updated pistons and rings. 60-80 labor hours at specialty shop. McLaren issued service bulletin but no recall—many owners fighting for goodwill coverage.
Estimated cost: $35,000-55,000
Transmission Oil Cooler Line Leaks
Common · medium severityTypical onset: 20,000-50,000 mi
Symptoms: Transmission fluid pooling under vehicle, Burning smell after hard driving, Transmission temperature warning on dash, Slipping or harsh shifts when hot
Fix: Quick-disconnect fittings on oil cooler lines crack or O-rings fail, especially after track use. Access requires partial undertray removal. 3-5 hours labor. Replace both feed and return lines plus mounts as preventive measure.
Estimated cost: $1,800-3,200
Transmission Mount Failures
Occasional · medium severityTypical onset: 25,000-60,000 mi
Symptoms: Clunking noise during shifts or throttle transitions, Excessive driveline vibration at idle, Visible transmission sag or misalignment, Rough engagement into gear from neutral
Fix: Hydraulic transmission mounts fail from heat cycling and aggressive launches. Requires suspension drop and specialized tooling. 6-8 hours labor. Replace all three mounts simultaneously—they fail in sequence.
Estimated cost: $3,500-5,500
Shift Solenoid Pack Failures
Occasional · high severityTypical onset: 30,000-70,000 mi
Symptoms: Limp mode with transmission fault codes, Harsh or delayed shifts, particularly 2-3 and 5-6, Stuck in single gear (usually 3rd or 5th), Intermittent loss of reverse
Fix: SST dual-clutch transmission solenoid bodies fail from heat and contamination. Requires transmission drop and valve body removal. 12-16 hours labor. Replace entire solenoid pack and mechatronic unit seals, update software. Contaminated fluid accelerates failure—flush is mandatory.
Estimated cost: $6,500-9,500
Fuel Filter Clogging from Tank Liner Deterioration
Occasional · medium severityTypical onset: 25,000-55,000 mi
Symptoms: Fuel starvation under hard acceleration or cornering, Hesitation or stumble at high RPM, Check engine light with fuel trim or fuel pressure codes, Rough idle after spirited driving
Fix: Fuel tank liner sheds particles that clog high-pressure filter. Requires rear clamshell removal for tank access. 8-10 hours labor. Replace filter and inspect/clean tank—some cases require full tank replacement if liner contamination is severe.
Estimated cost: $2,800-4,500
Crankshaft Main Bearing Wear from Oil Starvation
Rare · high severityTypical onset: 40,000-80,000 mi
Symptoms: Deep knocking noise from bottom end at idle, Low oil pressure warnings, Metal shavings in oil during changes, Catastrophic engine failure (seized motor)
Fix: Linked to piston ring debris contaminating oil system or sustained high-G cornering on track. Requires complete engine removal and short-block replacement or crankshaft regrind. 70-90 hours labor. Often found during post-mortem of piston failures.
Estimated cost: $45,000-65,000
Buy only with comprehensive warranty or if you can afford a $50k engine replacement without blinking—the piston ring issue is a ticking time bomb even on low-mileage examples.
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.