Mercedes Classe B Turbo

Mercedes Classe B petrol or diesel turbo: does one manufacturer reference fit all power outputs?

No. On the Classe B, each engine variant — and often each power output within the same engine capacity — has its own distinct turbo with its own manufacturer reference. All turbos listed here are new, sold with no old unit to return.

Diesel side: from the OM 640 to the OM 654 — very different architectures

The first diesel generations of the Classe B are based on the OM 640 (160 CDI 90 hp, 180 CDI 109 hp, engine codes OM 640.940 and OM 640.942) and the OM 646 (2.2 CDI). These engines use variable-geometry turbos whose references are numerous and cannot be substituted from one engine code to another — the A640 and A611 prefixes illustrate this throughout the catalogue. More recently, the OM 651.930 (220 CDI) and the OM 654 (B 220 d 190 hp) use distinct turbos, identifiable by the A651 and A654 prefixes. The OM 607.951, fitted to certain B 160 and B 180 diesel models, belongs to yet another family, with its own Renault-Mercedes references (144 and 607 series).

Petrol side: the M 270 block in three power outputs

The Classe B 200 (156 hp), B 220 (184 hp) and B 250 (211 to 218 hp) all share the M 270 (engine codes M 270.910 and M 270.920), but each power output receives a differently calibrated turbo: references A2700900080, A2700901480 and A2700902980 are not interchangeable between 156 hp and 218 hp. The engine code stamped on the block — not just the engine capacity — is the essential starting point for selecting the correct turbo. Common symptoms on these turbocharged petrol engines include a whistling noise under acceleration, blue smoke at idle, or an abnormally slow rise in engine speed. On variable-geometry diesel versions, a faulty actuator frequently causes the engine to enter limp mode; checking the condition of the oil circuit and any potential fouling of the EGR or DPF is essential before replacing the turbo.