2009 MERCEDES-BENZ GL

Typical onset: 60,000-120,000 mi

Symptoms: Metallic rattling from engine on cold start that disappears when warm, Check engine light with timing-related codes, Sudden catastrophic engine failure with metal shavings in oil, Loss of oil pressure

Fix: The M273 V8 has plastic balance shaft gears that disintegrate and send debris throughout the engine, scoring bearings and cylinder walls. Once failed, requires complete engine rebuild or replacement. Short block replacement is 25-35 hours labor, full rebuild 35-45 hours. Many shops won't rebuild these—just quote reman engine.

Estimated cost: $12,000-22,000

Typical onset: 70,000-110,000 mi

Symptoms: Transmission fluid pooling under vehicle, Red fluid dripping from bell housing area, Transmission slipping or harsh shifts, Burnt transmission fluid smell

Fix: The cooler lines running to the transmission corrode and leak at the fittings, allowing trans fluid to escape and coolant to potentially mix with ATF. If coolant enters transmission, complete transmission failure follows within days. Requires dropping transmission for full access, replacing cooler lines and often the transmission itself if contaminated. 8-12 hours labor for lines only, 18-25 hours if transmission needs replacement.

Estimated cost: $1,800-8,500

Typical onset: 80,000-130,000 mi

Symptoms: Loud clunk when shifting from Park to Drive or Reverse, Vibration at idle in Drive, Visible sagging of transmission when inspected from underneath, Harsh engagement into gear

Fix: The hydraulic transmission mount fails and allows excessive drivetrain movement, causing harsh shifts and potential damage to cooler lines. Requires supporting transmission and replacing mount. 2-3 hours labor, straightforward job but expensive part.

Estimated cost: $600-1,200

Typical onset: 75,000-120,000 mi

Symptoms: Vehicle sits low on one or more corners after sitting overnight, Suspension warning light with 'AIRMATIC Visit Workshop' message, Compressor runs continuously, Rough ride quality or bottoming out

Fix: Air struts develop leaks at the rubber bellows, and the compressor wears out from overwork trying to maintain pressure. Each strut is 2-3 hours labor, compressor is 3-4 hours. Most owners end up replacing all four struts plus compressor over time. Some opt for coil spring conversion kit to eliminate the system entirely.

Estimated cost: $1,500-6,000

Typical onset: 90,000-140,000 mi

Symptoms: Check engine light with P2004/P2006/P2010 codes, Rough idle and hesitation, Loss of power especially at low RPM, Rattling noise from intake area

Fix: The variable intake manifold actuator motors fail, and the plastic flap arms inside can break off and get sucked into the engine. Requires removing intake manifold to replace actuators and inspect for broken flaps. If flaps broke off, may need cylinder head removal to extract debris. 4-6 hours labor for actuators only, 12+ hours if heads must come off.

Estimated cost: $1,200-4,500

Typical onset: 100,000-150,000 mi

Symptoms: Gear oil leak from front differential, Whining or grinding noise during acceleration, Clunking from front end on turns, Vibration at highway speeds

Fix: The front differential seals leak and if not addressed, the unit runs low on fluid and destroys itself. Seal replacement is 3-4 hours if caught early. Complete differential replacement or rebuild is 8-12 hours and requires special tools for 4MATIC system.

Estimated cost: $800-4,500

Typical onset: 80,000-130,000 mi

Symptoms: Hard starting especially when hot, Rough running and misfires, Long cranking before engine fires, Loss of power under load

Fix: The high-pressure fuel pump on the M273 can fail, and direct injectors develop carbon buildup and internal failures. Pump replacement is 4-5 hours, injectors are 6-8 hours for the set due to intake removal requirements. Often needs both pump and injectors by 120k miles.

Estimated cost: $2,200-5,500