The 2007 ML500 W164 with the M113 5.0L V8 is a capable SUV undermined by serious engine durability issues and a transmission cooling system that fails predictably. Balance shaft problems and porous cylinder wall casting lead to catastrophic engine failures that often aren't economically repairable.
Balance Shaft Gear Failure Leading to Catastrophic Engine Damage
Common · high severityTypical onset: 80,000-140,000 mi
Symptoms: Metallic rattling from engine bay especially on cold starts, Check engine light with timing-related codes, Sudden loss of power followed by catastrophic engine failure, Metal shavings in oil during changes
Fix: Balance shaft gear deteriorates and fragments scatter through the engine destroying bearings, cylinder walls, and oil pump. Requires complete engine rebuild or replacement. 25-35 labor hours for proper rebuild including machine work, or 18-22 hours for used engine swap.
Estimated cost: $8,000-15,000
Cylinder Wall Porosity and Piston Scuffing
Occasional · high severityTypical onset: 100,000-160,000 mi
Symptoms: Excessive oil consumption (1 quart per 1,000 miles or more), Blue smoke on startup or acceleration, Loss of compression in one or more cylinders, Rough idle and misfires
Fix: Factory Nikasil-like coating on cylinder walls breaks down or casting porosity allows oil burning. Requires engine teardown, bore inspection, and either sleeving cylinders or complete short block replacement. 28-35 labor hours for proper repair.
Estimated cost: $7,500-12,000
Transmission Oil Cooler and Line Failure
Common · high severityTypical onset: 70,000-120,000 mi
Symptoms: Pink fluid under vehicle or on transmission bell housing, Transmission slipping or delayed engagement, Milky appearance to transmission fluid (coolant contamination), Overheating transmission or engine
Fix: External oil cooler develops leaks or internal cooler in radiator fails allowing cross-contamination of fluids. Requires cooler replacement, complete transmission fluid flush (often multiple cycles), and sometimes transmission rebuild if contamination occurred. 4-6 hours for cooler only, add 8-12 hours if transmission damaged.
Estimated cost: $1,200-2,500 (cooler only), $4,500-7,000 (with transmission work)
Transmission Mount Collapse
Common · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Clunking when shifting from Park to Drive or Reverse, Vibration at idle in gear, Visible sagging of transmission if inspected from below, Harsh shift quality
Fix: Rubber transmission mount deteriorates allowing excessive powertrain movement. Replacement requires supporting transmission, removing crossmember. Often replace all engine/trans mounts while in there. 2-3 hours for trans mount alone, 4-5 hours if doing all mounts.
Estimated cost: $400-800 (trans mount), $1,200-1,800 (all mounts)
Connecting Rod and Main Bearing Wear
Occasional · high severityTypical onset: 120,000-180,000 mi
Symptoms: Knocking sound from lower engine that increases with RPM, Low oil pressure warnings especially at idle when hot, Metal particles in oil filter media, Progressive increase in noise over weeks or months
Fix: Age and oil contamination from balance shaft debris or extended intervals cause bearing wear. Requires complete teardown, crankshaft measurement/possible machining, and bearing replacement. If crank is damaged, needs replacement or regrinding. 22-28 labor hours.
Estimated cost: $5,500-9,000
Airmatic Suspension Failure
Common · medium severityTypical onset: 80,000-130,000 mi
Symptoms: Vehicle sits low on one or more corners, Airmatic warning light on dash, Compressor runs constantly, Rough ride quality or bottoming out
Fix: Air struts develop leaks, compressor fails, or valve block malfunctions. Struts are most common failure. Each strut 2-3 hours, compressor 3-4 hours, valve block 4-5 hours. Many owners convert to coil springs to eliminate recurring costs.
Estimated cost: $800-1,500 per strut, $1,800-2,500 compressor, $3,500-5,500 coil conversion
Hard pass unless you're getting it for $3,000-4,000 with a documented fresh engine - the M113 in this chassis has catastrophic failure modes that exceed the vehicle's remaining value.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.