2018 MERCEDES-BENZ S63 AMG

Typical onset: 40,000-80,000 mi

Symptoms: Sudden loud knocking or rattling from bottom end at idle, Metal shavings in oil during routine changes, Check engine light with low oil pressure codes, Complete engine seizure in worst cases—happens without prior warning in many instances

Fix: Complete engine teardown and rebuild required: rod bearings, main bearings, crank polishing or replacement if scored, piston inspection. 35-50 labor hours for full rebuild. Many owners opt for factory reman longblock due to complexity and precision required. This is the M157's Achilles heel—oiling system can't keep up under high load, starves bearings, and carnage follows.

Estimated cost: $18,000-35,000

Typical onset: 50,000-90,000 mi

Symptoms: Transmission fluid puddles under vehicle, typically passenger side, Burnt transmission fluid smell after driving, Transmission overheating warnings on dash, Slipping or harsh shifting as fluid level drops

Fix: Replace transmission cooler lines and seals. Lines run along frame rail and rot from road salt/debris. Sometimes cooler itself needs replacement if internally contaminated. 4-6 hours labor. Catch it early before trans gets damaged from low fluid.

Estimated cost: $1,200-2,200

Typical onset: 60,000-100,000 mi

Symptoms: Rattling sound from engine bay on cold start that fades when warm, Loss of boost pressure and reduced power, Check engine light with underboost/overboost codes (P0299, P0234), Turbo whistle or whine changes pitch abnormally

Fix: Wastegate actuator arms wear and rattle inside turbos—endemic to this platform. Requires turbocharger removal and rebuild or replacement. 12-16 hours labor per side if doing both. Many shops won't rebuild these—straight to new or reman units.

Estimated cost: $4,500-8,000

Typical onset: 70,000-110,000 mi

Symptoms: Vehicle sits low on one corner after sitting overnight, ABC warning light illuminated on dash, Hydraulic fluid puddles (green fluid) under vehicle, Suspension feels bouncy or uncontrolled, especially over bumps

Fix: ABC struts, hydraulic lines, or pump seals fail. Strut replacement is 3-4 hours per corner. Pump is 6-8 hours. System is expensive and complex—many owners convert to conventional suspension (coilover kits available) if multiple components fail. Hydraulic fluid is hygroscopic and expensive.

Estimated cost: $2,800-6,500

Typical onset: 60,000-100,000 mi

Symptoms: Compressor runs constantly or excessively, Vehicle sags on one or more corners, Airmatic warning on dash with fault codes, Hissing sound from struts indicating air leak

Fix: Air struts develop leaks in bellows or seals; compressor wears from overwork. Strut replacement is 2-3 hours per corner. Compressor replacement is 4-5 hours. Often need to address multiple corners simultaneously as they age together. Aftermarket options exist but quality varies.

Estimated cost: $1,800-4,000

Typical onset: 50,000-80,000 mi

Symptoms: Clunk when shifting from Park to Drive or Reverse, Vibration through cabin at idle in gear, Excessive driveline movement visible during hard acceleration, Transmission feels 'sloppy' during shifts

Fix: The 722.9 transmission in this car is heavy and the mount fatigues from the torque. Replacement is straightforward—support trans, swap mount. 2-3 hours labor. Often done with engine mounts if those are also sagging.

Estimated cost: $600-1,200

Typical onset: 50,000-90,000 mi

Symptoms: White smoke from exhaust (coolant burning), Coolant loss with no visible external leaks, Overheating or fluctuating coolant temps, Milky oil or coolant in expansion tank, Often occurs after bearing damage causes block warping

Fix: M157 head gaskets fail, sometimes secondary to overheating from bearing failure or oiling issues. Heads must come off, surfaces machined, bolts replaced (TTY), new gaskets. 18-24 hours labor. If you're this deep, inspect bottom end carefully—often both problems coexist.

Estimated cost: $6,000-10,000