What are the common issues with the r320 engine?
4 Answers
The common issues with the r320 engine include: 1. The engine produces a significant amount of carbon deposits. When gasoline is not fully absorbed into the engine, it forms carbon deposits, leading to incomplete combustion, which causes the car to shake and increases fuel consumption; 2. The oil quality does not match the engine. If the oil viscosity is too high, it can lead to increased fuel consumption and carbon deposit formation; 3. The throttle or fuel injector has not been cleaned for a long time, or the engine has a misfire. This affects the atomization and combustion of fuel, leading to a series of problems. The Mercedes-Benz r320 is equipped with a 3.0t twin-turbocharged V6 engine, with a maximum power of 200 kW and a maximum torque of 400 Nm. The maximum torque is achieved between 1300 and 4500 rpm, paired with a 7-speed automatic transmission, achieving a 0-100 km/h acceleration time of 7.8 seconds.
I'm very familiar with the 3.0T engine in the R320. Several friends who drive this car have complained about its common issues. Vehicles produced before 2016 are prone to timing chain problems. Over time, the chain tensioner loses pressure, causing a loud rattling noise during cold starts, sounding like a tractor. The most troublesome issue is the coolant leakage from the oil filter housing. As the plastic components age, coolant mixes with the engine oil. I've seen several cars where the oil drained from the pan had a milky, emulsified appearance. The camshaft adjuster is another frequent failure point, with symptoms including a prolonged cranking time of several seconds before the engine starts in the morning. The turbocharger's intake pipe connection is also prone to cracking, leading to noticeable power loss due to air leaks. While replacement parts aren't expensive, the labor-intensive disassembly and reassembly process makes repairs particularly costly.
My buddy who runs an auto repair shop sees this M276 engine every day and says it has a crappy design—the oil filter housing is integrated with the coolant passage. The plastic parts can't withstand high temperatures, and within three to five years, it's guaranteed to leak coolant, which then flows into the oil filter, turning the oil into a milky mess. In severe cases, it can even cause cylinder scoring. Another hidden issue is the intake manifold flap motor—when it fails, it triggers a fault code, causing intermittent power loss during hard acceleration. The balance shaft module sensor is also prone to acting up; located near the oil pan, its connector can loosen over time due to bumps, triggering the engine light. While it's not as prone to air suspension failures as older Mercedes models, fixing these engine issues can still cost a few grand.
While researching this car, I discovered a pattern: 100,000 kilometers is a critical milestone. The most common issue is turbocharger pipe leaks, where the rubber bellows crack due to high-temperature aging, producing a whistling sound during hard acceleration. Worn timing chain sprockets cause noticeable cold-start rattling—dealerships often recommend replacing the entire chain trio, but just replacing the tensioner can save half the cost. Camshaft adjusters have a high failure rate, frequently triggering fault codes 0341/0340. Recently, I helped fix two cases of crankshaft pulley delamination—once the rubber layer cracked, the entire pulley flew off, disabling the alternator and A/C. Aftermarket parts offer better value for these components.
