2008 Mercedes-Benz R350
The 2008 Mercedes-Benz R350 is a luxury crossover SUV that offered a blend of passenger space, comfort, and performance. For 2008, the R350 was available with a 3.5L V6 engine that produces 268 horsepower and 258 lb-ft of torque and was mated to a 7-speed automatic transmission. Some owners appreciate the R350’s spacious interior and smooth ride, while others find the vehicle’s reliability and repair costs to be drawbacks.
Engine
3.5L V6
- Balance Shaft Sprocket Wear
- Description/Symptoms: This is a common issue on M272 engines (the 3.5L V6 used in the R350). Premature wear of the balance shaft sprocket can lead to engine noise, rough running, and eventually, engine failure. Symptoms include a check engine light with codes related to camshaft timing, rattling noises from the engine, and decreased performance.
- Solution: Replacement of the balance shaft, along with associated timing components (timing chain, tensioner, guides).
- Estimated Cost to Fix: $3,000 - $6,000+
- Recalls: None Found
- Intake Manifold Tumbler Flap Failure
- Description/Symptoms: The plastic tumbler flaps in the intake manifold can break, leading to vacuum leaks and reduced engine performance. Symptoms include a check engine light, poor fuel economy, and rough idling.
- Solution: Replacement of the intake manifold.
- Estimated Cost to Fix: $800 - $1,500+
- Recalls: None Found
- Camshaft Position Sensor Failure
- Description/Symptoms: The camshaft position sensors can fail, leading to rough running, stalling, and a check engine light.
- Solution: Replacement of the faulty camshaft position sensor.
- Estimated Cost to Fix: $150 - $300+
- Recalls: None Found
Transmission
7G-Tronic 722.9 7-Speed Automatic
- Valve Body Issues
- Description/Symptoms: The valve body in the 722.9 transmission is prone to wear and can cause various issues, including harsh shifting, delayed engagement, slipping, and failure to shift. This is often due to wear of the solenoids and the valve body itself.
- Solution: Replacement or rebuild of the valve body, often including new solenoids.
- Estimated Cost to Fix: $800 - $2,500+
- Recalls: None Found
- Torque Converter Failure
- Description/Symptoms: The torque converter can fail, causing shuddering, vibration, and poor performance.
- Solution: Replacement of the torque converter.
- Estimated Cost to Fix: $1,000 - $3,000+
- Recalls: None Found
- Conductor Plate Failure
- Description/Symptoms: The conductor plate, which houses the transmission’s electronic control unit (TCU) and sensors, can fail. This can lead to erratic shifting, limp mode, and a check engine light.
- Solution: Replacement of the conductor plate.
- Estimated Cost to Fix: $800 - $2,000+
- Recalls: None Found
Suspension
- Air Suspension Issues (Airmatic)
- Description/Symptoms: The Airmatic air suspension system, if equipped, is known for problems. Air leaks can develop in the air struts, compressor failure, or issues with the air lines and valve block can occur. Symptoms include the vehicle sagging, uneven ride height, and a warning light on the dashboard.
- Solution: Replacement of the faulty air strut(s), air compressor, or repair of air lines/valve block.
- Estimated Cost to Fix: $800 - $2,000+ per strut; $500 - $1,500+ for compressor.
- Recalls: None Found
- Ball Joint Failure
- Description/Symptoms: The ball joints can wear out, causing noise, vibration, and poor handling.
- Solution: Replacement of the faulty ball joints.
- Estimated Cost to Fix: $200 - $500+ per ball joint
- Recalls: None Found
Electrical
- EIS/ESL Failure
- Description/Symptoms: The Electronic Ignition Switch (EIS) and Electronic Steering Lock (ESL) are prone to failure. This can prevent the car from starting or unlocking the steering wheel.
- Solution: Replacement of the EIS and/or ESL.
- Estimated Cost to Fix: $800 - $2,000+
- Recalls: None Found
- SAM (Signal Acquisition Module) Failure
- Description/Symptoms: The SAM controls various electrical functions. Failure can lead to a range of issues, including lighting problems, malfunctioning wipers, and other electrical gremlins.
- Solution: Replacement of the faulty SAM.
- Estimated Cost to Fix: $500 - $1,500+
- Recalls: None Found
- Battery Drain
- Description/Symptoms: The R350 can suffer from parasitic battery drain due to various electrical components not shutting down properly.
- Solution: Diagnosing and repairing the faulty component causing the drain.
- Estimated Cost to Fix: Varies widely depending on the cause.
- Recalls: None Found
Exterior
- Sunroof Issues
- Description/Symptoms: The sunroof mechanism can fail, leading to difficulty opening or closing, or leaks.
- Solution: Repair or replacement of the sunroof mechanism.
- Estimated Cost to Fix: $500 - $1,500+
- Recalls: None Found
Interior
- Navigation/Infotainment System Failure
- Description/Symptoms: The navigation and infotainment system can experience software glitches or hardware failures, leading to a blank screen, inability to control functions, or other issues.
- Solution: Repair or replacement of the head unit or associated components.
- Estimated Cost to Fix: $300 - $1,500+
- Recalls: None Found
Summary
The 2008 Mercedes-Benz R350 can be a comfortable and spacious vehicle, but it’s important to be aware of the potential issues. The most significant problems relate to the engine (balance shaft), transmission (valve body), air suspension (if equipped), and electrical systems. Repair costs can be high, especially for the balance shaft and air suspension issues. Potential buyers should have a pre-purchase inspection performed by a qualified mechanic familiar with Mercedes-Benz vehicles to identify any existing or potential problems. While the issues aren’t necessarily severe, the potential cost to fix them is.