2015 MERCEDES-BENZ ML

Typical onset: 40,000-80,000 mi

Symptoms: Metallic knocking or ticking from engine at idle that worsens with RPM, Metal shavings in oil during changes, Sudden loss of oil pressure with warning light, Complete engine seizure without warning in worst cases

Fix: M278 engines suffer balance shaft module failures that send metal through the entire engine, destroying bearings, pistons, and cylinder walls. Only fix is complete engine replacement or full rebuild with updated balance shaft module. 25-35 labor hours for engine R&R plus machine work.

Estimated cost: $15,000-25,000

Typical onset: 60,000-100,000 mi

Symptoms: Transmission fluid appears milky or strawberry-milkshake colored, Coolant level drops without external leaks, Harsh shifting or slipping between gears, Check engine light with transmission-related codes

Fix: The transmission cooler inside the radiator fails internally, mixing coolant and ATF. This destroys the 722.9 7-speed transmission within days if not caught early. Requires new radiator, transmission fluid flush (or full trans rebuild if contaminated), and all cooler lines. 8-12 hours labor if caught early, add 20-25 hours if transmission is damaged.

Estimated cost: $1,800-3,500 (early catch) / $8,000-12,000 (with transmission damage)

Typical onset: 70,000-110,000 mi

Symptoms: Clunking when shifting from Park to Drive or Reverse, Vibration through chassis at idle in Drive, Excessive drivetrain movement visible when accelerating hard, Transmission tunnel heat increasing in cabin

Fix: Hydraulic transmission mounts fail internally, allowing excessive drivetrain movement. Common on both engine options but worse with the V8. Requires OEM Mercedes mounts (aftermarket fails quickly). 3-4 hours labor for both mounts.

Estimated cost: $800-1,400

Typical onset: 80,000-130,000 mi

Symptoms: Cold-start rattle for 2-3 seconds that persists or worsens, Check engine light with camshaft position correlation codes (P0016, P0017), Reduced power and rough idle, Metallic rattling under acceleration

Fix: The M276 3.5L V6 develops timing chain stretch, particularly on the right bank. Requires both timing chains, guides, tensioners, cam adjusters, and valve cover gaskets. Early catch prevents valve damage. 18-22 hours labor on ML due to tight engine bay.

Estimated cost: $4,500-6,500

Typical onset: 60,000-90,000 mi

Symptoms: Vehicle sits low on one corner after sitting overnight, Airmatic warning message with suspension malfunction, Compressor runs excessively (audible under vehicle), Rough ride quality with loss of adaptive damping

Fix: Air struts develop leaks at the bellows or internal seals. Compressor overworks and fails secondary to leaking struts. Address struts first before replacing compressor. Each strut is 2-3 hours, compressor adds 3-4 hours. OEM or Arnott remanufactured recommended.

Estimated cost: $1,200-2,000 per strut / $1,800-2,800 for compressor

Typical onset: 50,000-90,000 mi

Symptoms: Fuel smell in engine bay or cabin, Visible fuel seepage on top of engine, Hard starting after sitting overnight, Fuel pressure loss with long crank times

Fix: Plastic fuel filter housing cracks or o-rings fail, causing fuel leaks on top of the engine (fire hazard). The entire housing assembly should be replaced, not just filter. 2-3 hours labor on V6, 3-4 on V8 due to access.

Estimated cost: $600-1,100