2010 MERCEDES-BENZ G-CLASS

Typical onset: 60,000-120,000 mi

Symptoms: Metallic rattling noise from engine bay at startup or idle, Check engine light with cam position correlation codes, Sudden catastrophic engine failure with metal shavings in oil, Loss of oil pressure

Fix: The M273 V8 has poorly-designed balance shaft gears that strip and fail, sending metal through the entire engine. Once it lets go, you're looking at complete engine rebuild or replacement. This is NOT a repair-in-place job—engine must come out. Expect 40-60 hours labor for rebuild with new balance shaft delete kit, pistons, bearings, head work. Many shops recommend going straight to a reman long-block.

Estimated cost: $15,000-25,000

Typical onset: 70,000-110,000 mi

Symptoms: Transmission fluid puddles under vehicle, Low transmission fluid warning light, Transmission slipping or harsh shifts due to low fluid, Pink or red fluid visible on frame rails

Fix: The 722.9 seven-speed transmission runs hot in the G-Class due to weight and aerodynamics. The steel cooler lines rust and develop pinhole leaks, or the rubber hoses at the connections deteriorate. Replace all cooler lines and flush the system. Takes 3-4 hours if no cross-threading on fittings.

Estimated cost: $800-1,400

Typical onset: 60,000-100,000 mi

Symptoms: Clunking when shifting from Park to Drive or Reverse, Excessive vibration through cabin at idle, Visible transmission sag when inspected on lift, Harsh engagement into gear

Fix: The transmission mount is oil-filled and fails from heat and age. The G-Class weighs over 5,500 lbs, which accelerates wear. Replacement requires supporting the transmission and unbolting the crossmember. Two mounts typically need replacement. Labor runs 2-3 hours.

Estimated cost: $600-1,000

Typical onset: 80,000-130,000 mi

Symptoms: Rough idle and misfires under load, Fuel pump whining or failing repeatedly, Check engine light with multiple fuel trim codes, Black debris visible in fuel filter

Fix: The plastic fuel tank baffles and internal components deteriorate, sending debris through the system. This clogs injectors and kills fuel pumps. Proper fix requires tank removal, cleaning, and replacement of pump assembly, filter, and often injectors. Fuel tank R&R alone is 6-8 hours due to body-on-frame construction and exhaust routing.

Estimated cost: $2,500-4,500

Typical onset: 90,000-140,000 mi

Symptoms: White smoke from exhaust on cold start, Coolant loss with no visible leaks, Overheating under load, Milky oil on dipstick or oil cap, Misfires on one bank

Fix: The M273 runs hot and the head gaskets can fail, especially if the balance shaft issue caused overheating. Both heads must come off—this is a 20-25 hour job minimum. While you're in there, most techs recommend addressing valve stem seals and doing a full timing chain inspection. If the block is already damaged from balance shaft debris, you're better off doing a full engine rebuild.

Estimated cost: $6,000-9,000

Typical onset: 50,000-110,000 mi

Symptoms: Random no-start condition, especially when hot, Engine stalling while driving, Check engine light with crank/cam correlation codes, Starter cranks but engine won't fire

Fix: The crank sensor on the M273 is buried behind the starter motor and gets heat-soaked. It fails intermittently, leaving you stranded. Diagnosis can be tricky because it often tests fine when cold. Replacement requires starter removal and working in tight quarters. Allow 2-3 hours labor.

Estimated cost: $400-700