Mercedes-Benz M157 / M152

AMG's 5.5-litre turbocharged V8, the performance counterpart to the M278 and the engine behind the 63 badge of its generation. Turbochargers inside the vee, like its sibling.

The hot-vee layout is the whole of its service character: everything between the banks runs extremely hot and is very hard to reach, so heat-cycled wiring, coolant lines and sensors there fail earlier than on a naturally aspirated V8 and labour dominates any estimate.

Camshaft adjuster and timing-chain wear is the fault most specific to the family, presenting as a start-up rattle and eventually correlation codes, and oil leaks from the turbocharger feed lines run down into the vee where they are hard to see and easy to blame on something else.

⚑ The M152 on this page is NOT turbocharged. It is the naturally aspirated 5.5 of the SLK 55 AMG — the same block, without the pair of turbochargers in the vee, and with none of the boost-related failures that define the M157. A fault, a part or a service interval quoted for the 5.5 AMG V8 is worth nothing until somebody says which, and this page declares no aspiration for that reason.