2008 Mercedes-Benz ML350

The 2008 Mercedes-Benz ML350 is a mid-size luxury SUV known for its comfortable ride, spacious interior, and refined styling. The ML350 comes standard with a 3.5L V6 engine producing 268 horsepower and 258 lb-ft of torque. Other available engine options include a 3.0L diesel V6 (ML320 CDI/ML350 BlueTEC) and a 5.5L V8 (ML550). All engines were paired with a 7-speed automatic transmission (7G-TRONIC). Owners often praise the ML350 for its smooth driving experience and luxurious features, but some common complaints include electrical issues, specifically the sunroof, and reliability concerns.

Engine

3.5L V6

• Balance Shaft Sprocket Wear
  • Description/Symptoms: A common issue in M272 engines (including the 3.5L V6 in the 2008 ML350) is premature wear of the balance shaft sprocket. Symptoms include a check engine light, rough running engine, and unusual noises from the engine. The issue is related to the soft metal used in the original sprocket.
  • Solution: Replacement of the balance shaft and sprocket with an updated, hardened version.
  • Estimated Cost to Fix: $2,500 - $5,000+
  • Recalls: None Found
• Camshaft Adjuster Solenoid Failure (Cam Magnet)
  • Description/Symptoms: Malfunction indicator lamp activation, poor engine performance, rough idle, and potential stalling. Often accompanied by diagnostic trouble codes related to camshaft timing.
  • Solution: Replacement of the faulty camshaft adjuster solenoid.
  • Estimated Cost to Fix: $200 - $500+
  • Recalls: None Found
• Oil Leaks (Valve Cover and Oil Filter Housing)
  • Description/Symptoms: Visible oil leaks around the valve covers or oil filter housing, burning oil smell, and low oil level.
  • Solution: Replacement of the valve cover gaskets and/or oil filter housing gasket.
  • Estimated Cost to Fix: Valve Cover Gasket: $300 - $800+; Oil Filter Housing Gasket: $400 - $1,000+
  • Recalls: None Found

3.0L Diesel V6

• Intake Port Shutoff Motor Failure
  • Description/Symptoms: Check engine light, reduced engine performance, and diagnostic trouble codes related to the intake manifold or swirl flaps. The motor that controls the intake port shutoffs can fail, leading to airflow restrictions.
  • Solution: Replacement of the intake manifold with the integrated shutoff motor.
  • Estimated Cost to Fix: $1,000 - $2,500+
  • Recalls: None Found
• Glow Plug Failure
  • Description/Symptoms: Difficult starting, especially in cold weather, check engine light, and rough idling.
  • Solution: Replacement of the faulty glow plugs.
  • Estimated Cost to Fix: $200 - $600+
  • Recalls: None Found
• Oil Cooler Leaks
  • Description/Symptoms: Coolant loss, oil in coolant, or external oil leaks.
  • Solution: Replacement of the oil cooler and associated seals.
  • Estimated Cost to Fix: $800 - $2,000+
  • Recalls: None Found

5.5L V8

• Valve Lifter/Hydraulic Element Noise
  • Description/Symptoms: Ticking or tapping noise from the engine, especially at idle or when cold. This can be due to wear or failure of the hydraulic valve lifters/elements.
  • Solution: Replacement of the valve lifters/hydraulic elements.
  • Estimated Cost to Fix: $1,500 - $4,000+
  • Recalls: None Found
• Oil Leaks (Valve Cover and Oil Filter Housing)
  • Description/Symptoms: Visible oil leaks around the valve covers or oil filter housing, burning oil smell, and low oil level.
  • Solution: Replacement of the valve cover gaskets and/or oil filter housing gasket.
  • Estimated Cost to Fix: Valve Cover Gasket: $300 - $800+; Oil Filter Housing Gasket: $400 - $1,000+
  • Recalls: None Found

Transmission

7G-TRONIC (722.9)

• Conductor Plate Failure
  • Description/Symptoms: Erratic shifting, transmission stuck in gear, limp mode, and diagnostic trouble codes related to the transmission control module (TCM) or conductor plate. The conductor plate houses the transmission’s sensors and control circuitry and is a common failure point in the 722.9 transmission.
  • Solution: Replacement of the conductor plate. In some cases, the entire valve body may need to be replaced. Recoding the TCM may also be necessary.
  • Estimated Cost to Fix: $800 - $2,000+
  • Recalls: None Found
• Torque Converter Failure
  • Description/Symptoms: Shuddering during acceleration, especially at lower speeds, abnormal noises from the transmission, and poor fuel economy.
  • Solution: Replacement of the torque converter.
  • Estimated Cost to Fix: $1,500 - $3,500+
  • Recalls: None Found
• Valve Body Issues
  • Description/Symptoms: Hard shifting, delayed engagement, slipping between gears, and overall poor transmission performance.
  • Solution: Repair or replacement of the valve body.
  • Estimated Cost to Fix: $800 - $2,500+
  • Recalls: None Found

Suspension

• Airmatic Suspension Compressor Failure (If Equipped)
  • Description/Symptoms: Vehicle sagging, especially overnight, failure to maintain ride height, “Visit Workshop” warning light related to the air suspension system. The air compressor may fail due to wear or moisture intrusion.
  • Solution: Replacement of the air suspension compressor. Also, inspect the air lines and struts for leaks.
  • Estimated Cost to Fix: $800 - $2,000+
  • Recalls: None Found
• Airmatic Strut Leaks (If Equipped)
  • Description/Symptoms: Sagging vehicle, especially on one side, hissing sound from the suspension, and “Visit Workshop” warning light related to the air suspension system. Air struts can develop leaks over time, causing the system to lose pressure.
  • Solution: Replacement of the leaking air strut(s).
  • Estimated Cost to Fix: $800 - $2,500+ per strut (depending on location and brand)
  • Recalls: None Found
• Control Arm Bushing Failure
  • Description/Symptoms: Clunking noises from the suspension, especially when going over bumps, vague steering, and uneven tire wear.
  • Solution: Replacement of the control arm bushings or the entire control arm assembly.
  • Estimated Cost to Fix: Bushings only: $200 - $600+ per arm; Complete Control Arm: $400 - $1,000+ per arm
  • Recalls: None Found

Electrical

• Sunroof Issues
  • Description/Symptoms: Sunroof failing to open or close properly, getting stuck, making unusual noises, or leaking. The sunroof mechanism can be prone to failure.
  • Solution: Repair or replacement of the sunroof motor, cables, or entire assembly.
  • Estimated Cost to Fix: $300 - $1,500+
  • Recalls: None Found
• EIS (Electronic Ignition Switch) Failure
  • Description/Symptoms: Key not recognized, inability to start the vehicle, steering lock malfunction, and potential immobilization of the vehicle.
  • Solution: Replacement of the EIS and potentially reprogramming of the key.
  • Estimated Cost to Fix: $800 - $2,000+
  • Recalls: None Found
• Door Lock Actuator Failure
  • Description/Symptoms: Door not locking or unlocking properly, unusual noises from the door lock mechanism.
  • Solution: Replacement of the faulty door lock actuator.
  • Estimated Cost to Fix: $200 - $600+ per door
  • Recalls: None Found
• Fuel Pump Relay
  • Description/Symptoms: Vehicle stalls or fails to start, no fuel being delivered to the engine.
  • Solution: Replacement of the fuel pump relay.
  • Estimated Cost to Fix: $50 - $200+
  • Recalls: None Found
• Brake Light Switch Failure
  • Description/Symptoms: Brake lights not functioning, cruise control not working, difficulty shifting out of park.
  • Solution: Replacement of the brake light switch.
  • Estimated Cost to Fix: $100 - $300+
  • Recalls: None Found

Exterior

• Rust (Especially in areas with road salt)
  • Description/Symptoms: Visible rust on the body panels, undercarriage, and around wheel wells.
  • Solution: Rust repair, panel replacement, and rust prevention treatments.
  • Estimated Cost to Fix: Varies greatly depending on the severity of the rust.

Interior

• Climate Control Issues
  • Description/Symptoms: Air conditioning not blowing cold air, heater not blowing hot air, uneven temperature distribution, or unusual noises from the climate control system.
  • Solution: Diagnosis and repair of the A/C compressor, heater core, blower motor, blend door actuators, or refrigerant leaks.
  • Estimated Cost to Fix: Varies greatly depending on the component needing repair or replacement.
• Steering Wheel Lock Malfunction * Description/Symptoms: Key is recognized but the steering wheel is locked and vehicle fails to start, may be accompanied by a warning message on the instrument cluster. * Solution: Replacement of steering wheel lock and possibly the Electronic Ignition Switch (EIS) * Estimated Cost to Fix: $1000-$2500+ * Recalls: None Found

Summary

The 2008 Mercedes-Benz ML350 can be a comfortable and luxurious SUV, but it’s crucial to be aware of potential problems. The engine issues, particularly with the balance shaft sprocket in the 3.5L V6, can be very costly to repair. Transmission problems with the 7G-TRONIC are also prevalent. The Airmatic suspension, if equipped, can add to the maintenance costs. Electrical problems can range from minor to severe. Overall, the 2008 ML350 has the potential for some significant repair bills. Pre-purchase inspections are highly recommended.