Faults

Mercedes M270/M274 Timing Chain: A-Class, GLA & C-Class Guide to Diagnosis and Repair

The M270/M274 turbo petrol engine shares its timing chain design with the M271 — and the same stretch problem. But the transverse layout in the A-Class and GLA makes the repair more labour-intensive.

Mercedes M270/M274 Timing Chain: A-Class, GLA & C-Class Guide to Diagnosis and Repair

By the Mercedes Specialist London workshop · · Updated · 2 min read

M270/M274: the same problem, different packaging

The M270 (transverse, for A-Class, CLA, GLA) and M274 (longitudinal, for C-Class and E-Class) are 1.6 and 2.0-litre turbocharged petrol engines that replaced the M271 Kompressor. The timing chain design is similar, and they can suffer the same chain stretch issue — particularly on cars that have missed oil changes or used the wrong oil specification. However, the repair cost differs significantly between transverse and longitudinal installations because of access constraints.

2. Transverse vs longitudinal: why the cost differs

On the longitudinal M274 (C-Class, E-Class), the timing chain is at the front of the engine and is relatively accessible — similar to the M271. Repair cost: £1,200–£1,800. On the transverse M270 (A-Class, CLA, GLA), the engine is mounted sideways and the timing chain end is against the inner wing. Access requires removing the engine or the front subframe, adding several hours of labour. Repair cost: £1,400–£2,000. This is an important consideration when buying a used A-Class or GLA — the repair is more expensive than on a C-Class with essentially the same engine.

3. Diagnosis and prevention

Diagnosis is identical to the M271: read camshaft adaptation values on Xentry. Values above approximately 5 degrees indicate chain stretch. A cold-start rattle confirms the diagnosis. Prevention: use the correct MB-spec oil (typically MB 229.5 or 229.6, check your specific engine) and change it every 10,000 miles. The transverse installation puts the oil sump at a different angle, so the correct oil level is critical — overfilling or underfilling affects timing chain lubrication. Always check the oil level on level ground and use the dipstick or electronic oil level readout, not guesswork.

Frequently asked questions

  • What does a stretched Mercedes timing chain sound like?

    A metallic rattle on cold start, usually lasting 1-3 seconds and going quiet when warm. Often accompanied by a "camshaft / crankshaft correlation" fault code.

  • Is a major Mercedes engine repair worth doing?

    On well-kept cars, yes — most Mercedes engines are easily good for 250,000 miles after one major repair. We will give you a fixed-price quote and an honest view of the car's remaining life before you decide.

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