2010 MERCEDES-BENZ ML350 BLUETEC W164

Typical onset: 80,000-150,000 mi

Symptoms: Metallic rattling from low in the engine at idle or cold start, Metal shavings in oil during change, Sudden loss of oil pressure with warning light, Complete engine seizure in worst cases

Fix: The balance shaft gear in the OM642 can strip or the module bearings fail, dumping metal through the oiling system and wiping bearings. Repair requires full engine teardown: short block replacement or complete rebuild with updated parts. 25-35 hours labor for engine removal, disassembly, machine work, reassembly, and reinstall. Many shops recommend used/reman long block swap instead.

Estimated cost: $8,000-15,000

Typical onset: 70,000-120,000 mi

Symptoms: Milky or strawberry-colored coolant in expansion tank, Transmission slipping or harsh shifts, Overheating or limp mode, White smoke from exhaust on startup if coolant enters trans

Fix: The internal transmission cooler in the radiator fails, allowing ATF and coolant to mix—either direction kills the transmission. Must replace radiator, flush both systems completely, often requires transmission rebuild or replacement if contamination progressed. 4-6 hours for cooler/radiator, add 12-18 hours if trans needs rebuild.

Estimated cost: $1,500-6,500

Typical onset: 90,000-140,000 mi

Symptoms: Sudden catastrophic loss of power, Extreme metallic rattling from intake side, Check engine light with multiple misfire codes, Possible physical damage to pistons/valves if arm enters cylinder

Fix: Plastic swirl flap arms break off inside the intake manifold and can be ingested into cylinders. Requires intake manifold replacement with updated design, inspection/borescope of cylinders for damage. If damage occurred, you're into head removal or worse. Delete kits available. 6-10 hours for manifold alone, much more if internal damage.

Estimated cost: $2,000-8,000

Typical onset: 80,000-130,000 mi

Symptoms: Reduced power and limp mode, Excessive regeneration cycles, Strong diesel smell during regen, Warning light for exhaust filter, Increased fuel consumption

Fix: Short-trip driving and failed regens clog the DPF beyond recovery. Requires DPF replacement (expensive) or professional cleaning if caught early. Some owners do off-road delete in states where legal. 3-5 hours for R&R. OE DPF is $2,500+ part alone.

Estimated cost: $3,000-4,500

Typical onset: 100,000-150,000 mi

Symptoms: Rough idle or misfires on cold start, Black smoke from exhaust, Hard starting after sitting, Loss of power under load, Check engine light with injector-specific codes

Fix: Piezo injectors on OM642 are sensitive to fuel quality and carbon up or fail electrically. Replacement requires all six injectors at once (they're coded to ECU). 4-6 hours labor plus programming. Use only Bosch or OE injectors—cheap Chinese units fail immediately.

Estimated cost: $3,500-5,000

Typical onset: 90,000-130,000 mi

Symptoms: Harsh or delayed shifts, especially 2-3 and 3-4, Limp mode with no forward gears, Transmission fault codes stored, Slipping between gears

Fix: The 7G-Tronic 722.9 transmission develops electrical faults in the conductor plate (internal wiring harness) and valve body solenoids wear. Requires transmission pan drop, valve body removal, plate replacement, fresh fluid/filter, and adaptation. 8-12 hours labor.

Estimated cost: $2,000-3,500

Typical onset: 60,000-120,000 mi

Symptoms: Hard starting in cold weather, Extended cranking before start, White smoke on cold start, Glow plug warning light or check engine

Fix: Beru glow plugs swell in the head and seize, making removal difficult—broken plugs require head removal for extraction. Replace all six preventively at first sign with updated Bosch units. Budget 2-4 hours if they come out clean, 15+ hours if you break one and need head work.

Estimated cost: $600-4,000