Mercedes-Benz ML: M272/M273 Balance Shaft Sprocket Premature Wear

The M272 V6 and M273 V8 engines used a composite plastic balance shaft idler gear sprocket that wears prematurely. As teeth degrade, the timing chain slackens and the right-bank camshafts fall out of time. A class action lawsuit was settled by Mercedes-Benz in 2011 for approximately USD $4,000 per affected vehicle. Engines with serial numbers below 30468993 on M272 are most commonly affected, though failures outside this range are also documented.

• Cold-start timing chain rattle lasting more than 2–3 seconds
• Check engine light with P0016 or P0017 camshaft correlation codes
• Rough idle or misfire at low RPM
• Metallic debris or swarf in engine oil

1. 1

   Check engine serial number against the Mercedes published threshold (below 30468993 on M272).

2. 2

   Scan for P0016 and P0017 fault codes.

3. 3

   Listen at cold start for chain rattle lasting more than 2 seconds.

4. 4

   Confirm whether balance shaft sprocket, idler gear, and timing chain have been replaced as a set.

5. 5

   If a workshop inspection is possible: Drain a small oil sample and inspect for metallic swarf.

Parts involved: Timing chain.

≈A$5,980 to ≈A$11,960 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has the balance shaft sprocket and timing chain been replaced, and can you show a workshop invoice?”
• “What is the engine serial number?”
• “Have there ever been check engine lights or stored cam correlation codes?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.