MERCEDES 6420304517 Connecting Rod Piston Benz OM642 3.0L V6

( Manufacturer Part Number: 6420304517 ), ( Part Type: Rod Piston ), ( Manufacturer Warranty: 30 Days ), ( Country Of Origin: Germany )

Review MERCEDES benz 3.0l V6 Connecting Rod Piston #5 fits W211 W164 E350 ML350 2008

The **Mercedes-Benz 6420304517 (2008 W211/W164 E350 ML350 OM642 3.0L V6 Connecting Rod & Piston Set)** is a high-performance, precision-engineered component designed exclusively for the iconic **OM642 3.0L V6 diesel engine**, which powers the legendary **Mercedes-Benz E350 (W211) and ML350 (W164)** models from the late 2000s. This critical assembly plays a pivotal role in maintaining the engine s reliability, efficiency, and longevity, ensuring optimal combustion, reduced wear, and sustained power delivery key factors for both daily driving and demanding performance applications.

Crafted from **high-grade forged steel and precision-machined aluminum alloys**, these connecting rods and pistons are engineered to withstand the extreme stresses of high-pressure combustion cycles, thermal expansion, and continuous mechanical load. The **connecting rods** feature a **forged steel construction with optimized wall thickness and reinforced small-end bearings**, designed to minimize vibration, reduce noise, and enhance durability under heavy loads, whether in urban stop-and-go traffic or highway cruising. Their **hollow design** reduces weight while maintaining structural integrity, contributing to improved engine responsiveness and fuel efficiency a hallmark of Mercedes-Benz s engineering philosophy.

The **pistons**, meanwhile, are precision-forged from **aluminum-silicon alloys** with **titanium nitride (TiN) or ceramic coatings** to resist wear, scuffing, and thermal degradation, ensuring smooth operation even under prolonged high-load conditions. Their **dished or flat profiles** are meticulously calibrated to optimize combustion chamber geometry, improving torque output and reducing emissions while maintaining the engine s signature smoothness. The **piston rings**, typically included in the set, are engineered with **low-friction coatings** and **optimized cross-sections** to minimize oil consumption and maximize sealing efficiency, preventing blow-by and maintaining compression integrity critical for the OM642 s reputation for quiet, refined performance.

This **OEM-quality replacement part** is fully compatible with the **2008 model year E350 (W211) and ML350 (W164)**, ensuring a seamless fit with the engine s original specifications. Whether replacing worn components due to high mileage, engine modifications, or performance tuning, this connecting rod and piston set restores the engine to near-factory condition, enhancing reliability and performance. Ideal for **professional mechanics, performance tuners, and enthusiasts**, this part is a testament to Mercedes-Benz s commitment to precision engineering, offering a direct upgrade path for those seeking to preserve or enhance the legendary durability of the OM642 powerplant.

### **Pros and Cons of Buying a 2008 Mercedes-Benz E350 ML350 (W211/W164, OM642 3.0L V6, Engine Code 6420304517)**

#### **Pros**

1. **Reliability and Durability**

- The **OM642 3.0L V6** is a well-proven engine, known for its longevity when maintained properly. Many examples with high mileage (150,000 miles) still run reliably if serviced regularly.

- The **W211 (E-Class) and W164 (ML-Class)** platforms are robust, with solid chassis and suspension components, though some wear can be expected over time.

2. **Performance and Driving Experience**

- The **OM642** produces **258 265 hp** (depending on tuning) and **236 lb-ft of torque**, providing a smooth, linear power delivery that suits both daily driving and light towing (up to 3,500 lbs with proper setup).

- The **automatic transmission (7G-Tronic, if equipped)** is smooth and reliable, though some early models had minor software quirks that were later addressed.

- The **ML350 (W164)** offers a more upright, practical SUV body compared to the E-Class sedan, making it better for families or those who prefer a higher seating position.

3. **Comfort and Luxury**

- Mercedes-Benz is renowned for its **high-quality interior materials, sound insulation, and refined ride comfort**, especially in higher-trim models (e.g., **Elegance, Sport, or AMG trim** if available).

- **AMG-tuned versions** (if available) offer sportier handling and better performance, though they may require more frequent maintenance.

4. **Resale Value (Compared to Peers)**

- While not as strong as newer Mercedes models, the **W211/W164** retains decent resale value relative to competitors like BMW 5 Series or Audi A6.

- The **OM642** is less common than the **M272 (3.0L V6)** in later models, which can be an advantage if parts are still readily available.

5. **Availability of Parts and Aftermarket Support**

- The **OM642** is widely supported by aftermarket tuners (e.g., **MHD, JB4, or custom ECU tuning**) for power increases (up to **350 hp** with minor modifications).

- **Common issues** (e.g., oil leaks, timing chain wear) have well-documented fixes, and parts are still available from Mercedes dealerships and third-party suppliers.

6. **Fuel Efficiency (For a V6)**

- The **OM642** achieves ** 18 22 MPG combined** (city/highway), which is reasonable for a **3.0L V6** of its era. Later models with **start-stop systems** (if equipped) improve fuel economy slightly.

7. **Potential for Modifications**

- The **OM642** responds well to **intake, exhaust, and ECU tuning**, allowing for noticeable power gains without excessive stress on the engine.

- **Turbocharging (aftermarket)** is possible but requires careful engineering to avoid reliability issues.

---

#### **Cons**

1. **Common Mechanical Issues**

- **Oil Leaks:** The **valve cover gasket, oil filter housing gasket, and rear main seal** are frequent leak points, especially in higher-mileage examples.

- **Timing Chain & Tensioners:** The **timing chain** (not a belt) can stretch over time, leading to **timing issues, rattling noises, or catastrophic failure** if ignored. Replacement is recommended around **100,000 120,000 miles**.

- **Water Pump & Thermostat Housing:** The **water pump** often fails around **80,000 100,000 miles**, and the **thermostat housing gasket** can leak coolant.

- **Transmission (7G-Tronic):** Some early **7G-Tronic** transmissions had **rough shifting or delayed engagement**, though later revisions improved reliability. **Fluid changes** are crucial to prevent premature wear.

2. **Electrical & Infotainment Problems**

- **Older infotainment systems** (pre-2010) can be **glitchy, slow, or incompatible with modern smartphones**.

- **Electrical gremlins** (e.g., faulty sensors, wiring issues) are common, requiring patience and sometimes professional diagnosis.

- **Heated seats, mirrors, or steering wheel** may develop **intermittent failures** over time.

3. **Maintenance Costs**

- **Mercedes-Benz is not cheap to maintain**, especially if using dealership labor. **Oil changes, timing chain replacements, and transmission services** add up quickly.

- **Aftermarket parts** (e.g., gaskets, sensors) can be hit-or-miss in quality, so **brand-name replacements** are often preferred.

- **Towing or heavy loads** can stress the **transmission and drivetrain**, leading to premature wear.

4. **Safety & Crash Test Ratings**

- The **W211 (E-Class)** and **W164 (ML-Class)** were **not as highly rated** in modern crash tests compared to newer Mercedes models. While they are **safe by their era s standards**, they lack **advanced airbag systems and structural reinforcements** found in later models.

5. **Depreciation & Age-Related Wear**

- The **2008 model year** is **15 years old**, meaning **suspension bushings, shocks, and control arms** may need replacement.

- **Rust** can be an issue in **salted climates**, particularly on the **wheel wells, undercarriage, and brake lines**.

- **Tires, brakes, and fluids** will need **frequent replacement** compared to a new car.

6. **Fuel Costs & Emissions**

- **Gasoline prices fluctuate**, and a **3.0L V6** will consume more fuel than a modern hybrid or diesel alternative.

- **Emissions regulations** may make older models **less desirable** in some regions, though this is less of an issue for personal use.

7. **Potential for Hidden Problems**

- **Pre-purchase inspection (PPI) is highly recommended** many **OM642 engines** develop **internal wear** (e.g., **piston rings, cylinder walls**) if not maintained properly.

- **Oil consumption** (common in high-mileage examples).

- **Exhaust gas recirculation (EGR) valve failures** (can cause rough idling).

- **Carbon buildup** in intake valves (common in modern gasoline engines, including the OM642).

- **Transmission fluid condition** (burnt or low fluid indicates major issues).

---

### **Ending Conclusion**

The **2008 Mercedes-Benz E350 ML350 (OM642 3.0L V6)** is a **capable, comfortable, and enjoyable luxury SUV/sedan** that can be a **great value if purchased wisely**. It offers **solid performance, a refined ride, and Mercedes-Benz luxury**, but it comes with **notable maintenance costs and potential reliability concerns** if not properly cared for.

**Buyers who prioritize comfort, luxury, and driving enjoyment** over cutting-edge technology.

**Those who can afford regular maintenance** (oil changes, timing chain, transmission service).

**People who may modify the engine** (tuning, intake/exhaust) for better performance.

**Owners who don t mind occasional electrical quirks** in exchange for a premium driving experience.

**Budget-conscious buyers** expect **higher repair bills** than a modern used car.

**Those who want minimal maintenance** this is a **high-end vehicle that requires attention**.

**People who need the latest safety tech** (e.g., advanced driver aids, modern infotainment).

**Buyers in harsh climates** (salt, extreme heat/cold) without proper rust protection.

---

### **Recommendation**

- **Full service history** (oil changes every 5,000 7,500 miles, timing chain replacement, transmission fluid changes).

- **No oil leaks, smooth power delivery, and no transmission issues.**

- **A pre-purchase inspection (PPI) confirming no major hidden problems.**

** then it can be an excellent purchase.** The **OM642 is a forgiving engine** when treated right, and the **W211/W164 platforms** remain **comfortable and enjoyable** to drive.

- A **newer Mercedes (W204 E-Class, W166 ML)** for better

Details:

Warranty on electronic devices is void if identifying mark removed or has sign of tampering. Item will come as pictured.

part #: 6420304517 prices

• $59.99-$269.95

specifications pistonringro:

• for models: W211, W164, E350, Ml350
• for makes: Mercedes
• for years: 2008
• mpn: 6420304517
• part type: Rod Piston
• manufacturer warranty: 30 Days
• country of origin: Germany

seller pistonringro:

• rating: 99.7%
• city: Tampa, Florida
• # reviews: 8929

returns pistonringro:

• policy: Returns Accepted
• paid by: Buyer
• time: 30 Days

general pistonringro:

• Car Truck Parts Accessories > Engines Engine Parts > Pistons Rings
• condition: Used

offer pistonringro:

• options: Ship-to-home
• started: April 8, 2026
• quantity: 2
• sold: 0
• availability: In Stock

shipping pistonringro:

• cost: $13.00
• transit: 3-7 Days
• service: FedEx Ground / FedEx Home Delivery
• type: Fixed
• class: Standard
• carrier: FedEx

payments pistonringro:

• other
• credit card: Diners-club
• wallet: Paypal

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