M272 balance shaft gear wear (early petrol V6)
Attaches to W164 at chassis level · Engine · carried by 2 variants across 1 chassis
Overview
M272 balance shaft gear wear (early petrol V6) is a occasional fault recorded against W164 at chassis level, typically from 80–200k km. It shows up as a camshaft position fault code, a rough or lumpy idle, and a check engine light that returns after clearing. Where it's documented, the repair runs €3,000–€6,000 (engine out to replace the balance shaft gear at a specialist, costs dated 2026-07), and it can be partly checked before you buy. 2 variants across 1 chassis in this database inherit it.
What happens
Symptom. A camshaft position fault code, a rough or lumpy idle, and a check engine light that returns after clearing.
Cause. Balance shaft gears on M272 engines built inside the early range wore prematurely against the crankshaft gear. Later engines used a revised gear, so the engine number decides the risk rather than the mileage or the service book.
Later parts. Revised balance shaft gear on later production engines
Sources. Mercedes-Benz technical information on the revised M272 balance shaft gear
How to check it
Paperwork
Take the engine number and check it against the affected range before you look at anything else, because no amount of service history answers this. A stored camshaft correlation code is the other warning.
On these cars the folder is most of the value.
Every variant that carries this
| Variant | Chassis | Body | Years | Risk | Good buy | Cost as % of good buy |
|---|---|---|---|---|---|---|
| ML 320 CDI OM642 | W164 | SUV | 2005–2011 | R4 | €7,250 | 62% |
| ML 350 M272 | W164 | SUV | 2005–2011 | R4 | €6,600 | 68% |
The last column is the point. The same repair is an inconvenience on one variant and a reason to scrap the car on another. A failure costing a quarter of the vehicle's value changes the purchase decision regardless of how rare it is.