2006 MERCEDES-BENZ S320 CDI W220

Typical onset: 80,000-150,000 mi

Symptoms: Excessive white smoke on cold start, Sudden loss of compression across multiple cylinders, Metallic knocking or rattling from crankcase, Fuel dilution in oil (check dipstick smell), Abrupt power loss and limp mode

Fix: OM613 is notorious for piston ring land failure and bearing damage when exposed to poor-quality biodiesel or water-contaminated fuel. Pistons crack, rings seize, bearings spin. Repair requires full teardown: pistons, rings, bearings, often crankshaft machining or replacement. Engine-out job, 40-60 hours labor depending on damage severity. Many shops recommend short block or remanufactured long block rather than piecemeal rebuild due to collateral damage.

Estimated cost: $8,000-15,000

Typical onset: 70,000-120,000 mi

Symptoms: Strawberry milkshake appearance in transmission fluid, Erratic shifting or slipping under load, Overheating transmission (limp mode), Coolant loss with no external leaks visible, White residue in coolant reservoir

Fix: Internal transmission cooler in radiator fails, allowing coolant and ATF to mix. Transmission must be dropped, flushed extensively (often multiple times), cooler replaced (external aftermarket recommended), torque converter replaced, valve body cleaned or replaced. If caught early, 12-16 hours labor. If driven after contamination, full transmission rebuild required (add 20+ hours and $3k+ parts).

Estimated cost: $2,500-7,000

Typical onset: 60,000-100,000 mi

Symptoms: Clunk when shifting from Park to Drive or Reverse, Vibration at idle in gear, Excessive drivetrain movement visible during acceleration, Transmission tunnel heat or noise increase

Fix: 722.6 five-speed transmission is heavy; mounts fatigue and tear. Replacement requires lifting transmission slightly, 3-5 hours labor for both mounts. OEM mounts mandatory—aftermarket fail quickly. Should be done with engine mounts if those are also worn.

Estimated cost: $800-1,400

Typical onset: 90,000-140,000 mi

Symptoms: Hard starting or extended cranking, Rough idle with misfires, Black smoke under acceleration, Loss of power and poor fuel economy, P0200-series injector codes

Fix: OM613 injectors are sensitive to fuel quality and water intrusion. Failed injector can dump raw fuel into cylinder, washing cylinder walls and accelerating piston/ring failure. Injectors must be replaced as a set (six), fuel system flushed, fuel filter and water separator replaced. 8-10 hours labor. Testing injectors individually on test bench recommended before replacement to confirm failure.

Estimated cost: $3,500-5,500

Typical onset: 80,000-130,000 mi

Symptoms: Intermittent no-start condition, especially when hot, Stalling at idle or during deceleration, Rough running and misfires, Check engine light with P0335 or P0340 codes

Fix: Sensors fail due to heat cycling. Crankshaft sensor is behind starter motor (4-5 hours labor, starter removal required). Camshaft sensor on cylinder head is easier (1.5-2 hours). Replace both if one fails—they tend to go together. OEM-only parts.

Estimated cost: $600-1,200

Typical onset: 70,000-110,000 mi

Symptoms: Vehicle sagging on one or more corners overnight, Compressor running constantly or not at all, Suspension warning light and 'Visit Workshop' message, Harsh ride or bottoming out over bumps

Fix: Airmatic struts leak at diaphragm seals; compressor wears from overwork. Strut replacement 2-3 hours each corner. Compressor replacement 3-4 hours. Diagnose with Star Diagnostics to identify failed component. Aftermarket struts available (Arnott) at half OEM cost but shorter lifespan. Budget for all four struts if over 100k miles—they fail in sequence.

Estimated cost: $1,800-4,500