Mercedes M272 V6 / M273 V8 problems

The M272 V6 and M273 V8 share architecture and they share their most famous problem: the balance shaft and idler gears. Mercedes used a sintered metal gear that wasn't hardened correctly during a specific window of production. Over time the teeth on these gears wear down. The car throws a check engine code, often P0016 or P0017 — camshaft position correlation. The repair, if you catch it before secondary damage, is a balance shaft replacement on the V6 or idler gear replacement on the V8, $4,000-$8,000 at an independent Mercedes shop, double that at a dealer. Mercedes settled a class action on this and offered limited extended warranty coverage on affected VINs. If you own one of these engines and it's throwing camshaft correlation codes, the first thing to do is check whether your VIN is in the affected production window. The settlement details matter — Mercedes covered some VINs and not others, and the documentation requirements are specific. Beyond the balance shaft / idler gear issue, both engines develop camshaft adjuster (cam phaser) wear at higher mileage. The phasers are responsible for variable cam timing, and when they wear they produce a rattle on cold start similar to the Ford 5.4 problem. Replacement is $1,500-$2,500. The intake manifold has air flaps inside that route incoming air through different paths depending on engine load. The flap actuator linkages break and the flaps either get stuck or fall out of the manifold entirely. When that happens you get reduced power, check engine codes, and sometimes engine ingestion of the broken plastic pieces. Replacement intake manifold is $400-$800 in parts plus install. Owners of these Mercedes products who maintain them properly and address problems early get long lives — the bottom ends are durable, the chassis is well-built. The trap is buying a high-mileage example with deferred maintenance. The repair bills compound quickly on these engines once you fall behind.