We try to figure out what happened to the engine in my W204 C63 AMG, getting a new motor seems to be the best option.

The M156 displaces 6,208 cc (6.2 L; 378.8 cu in) and shares very little with other MercedesBenz engine families like the M155. The bore spacing, block design, and other features are unique to the AMG engine.

Although this engine displaces 6.2 litres, it is marketed as the "6.3" to commemorate Mercedes' famed 6.3 L M100 engine, its first production V8.

The engine uses a bore and stroke of 102.2 mm × 94.6 mm (4.02 in × 3.72 in). When introduced in the 2007 CLK63 AMG, output was 475 hp (482 PS; 354 kW) at 6,800 rpm with 630 N⋅m (465 lb⋅ft) of torque at 5,200 rpm. For the 2007 CLS63 and E63, output was 507 hp (514 PS; 378 kW) at 6,800 rpm with 630 N⋅m (465 lb⋅ft) of torque at 5,200 rpm. The 2007 ML63 had 503 hp (510 PS; 375 kW), and the 2008 C63 had 451 hp (457 PS; 336 kW). The final 2015 C63 had 500 hp (507 PS; 373 kW).

The engine, however, has been uprated to produce 518 hp (525 PS; 386 kW) and 465 lb⋅ft (630 N⋅m) of torque in the late S 63, E 63, SL 63, CLS 63 & CL 63 models[1].

Applications:

20062011 E 63 AMG
20062011 ML 63 AMG
2006 R 63 AMG
20062011 S 63 AMG
20062011 CL 63 AMG
20062010 CLK 63 AMG
20062010 CLS 63 AMG
20082015 C 63 AMG
20082011 SL 63 AMG
2013 Lucra LC470 R

M156 lawsuit:

In 2011, a class action lawsuit was filed in United States District Court in New Jersey against Daimler AG, MercedesBenz, MercedesAMG for alleged defects in the M156 engine contained in AMG vehicles built in 2007–2011 model years leading to premature wear. The plaintiff claimed the combination of cast nodular iron camshafts and 9310 grade steel valve lifters contributed to the premature wear, but the defendants had known about the defect since 2007.[1]

The lawsuit lasted approximately 14months. In November, 2012, litigation came to a halt when the New Jersey District Court dismissed the plaintiffs’ first amended complaint for lack of standing. The plaintiffs were given the opportunity to further amend their complaint to show that they had standing to sue, but plaintiffs made no further filings with the Court. On January 7, 2013, the Court signed an order closing the case. [2]