Engines · Mercedes-Benz
Mercedes-AMG M156 6.2 V8 common problems
The M156 is a 6,208cc naturally aspirated V8, badged 63, and the first V8 AMG designed entirely in-house. Built from 2006 to 2015, it replaced the supercharged 5.4 V8 in the 55 models and was succeeded by the twin-turbo M157 and M177; it was also fitted to the CLS63, ML63, S63 and CL63. Specialists rate it highly, and later engines in particular are largely trouble-free.
Common problems and what to look for on the M156
The known issues most worth checking when you view a car with this engine. None of them means a car is a bad buy, but they're worth knowing about before you buy, and a good history often shows they've been dealt with.
Cylinder head bolts on early engines
What to look for: With the engine cold, check the coolant level in the expansion tank against the markings, and ask whether it has needed regular topping up. Check the oil level and look at the dipstick and filler cap for milky residue. At start-up, watch the exhaust for white smoke that persists after warm-up, and feel for a misfire or rough idle. Ask for the engine number and for any invoice showing new head bolts.
Why it matters: On engines numbered up to 60 060658, built from 2006 to about the first half of 2010, the cylinder head bolts can corrode, stretch or break. Losing clamping force lets coolant into the cylinders and oil, and in severe cases can damage the engine. Mercedes issued a service bulletin in April 2011, and the fix is new head bolts and hydraulic lifters, with the pistons and rods checked while the heads are off; facelifted cars from 2011 have the revised bolts from the factory. Snapped bolts are rare, and a car with the work on file is in a good position.
Camshaft lobe and lifter wear
What to look for: Listen at a cold start with the bonnet open. A ticking or clattering from the top of the engine that carries on as it warms, or a misfire on the drive, is the thing to note. Ask whether the camshafts or lifters have been replaced and when the oil was last changed.
Why it matters: On early engines some lifters and camshaft lobes can wear prematurely. It is rare, and Mercedes acknowledged it in a 2009 service bulletin. The fix is a top-end rebuild with new camshafts and lifters, and later engines from 2011 have revised lifters. Frequent oil changes help, and invoices for a rebuild are a sign of a car that's been looked after.
Rattle at start-up from the camshaft adjusters
What to look for: From cold, listen for a loud rattle from the front of the engine in the first few seconds after start-up. On the drive, note any hesitation or poor throttle response, and have the fault memory read for camshaft timing codes if you can.
Why it matters: The camshaft adjusters, and the plates fitted to them, can wear and stop holding oil properly, which causes a start-up rattle and can lead to camshaft timing codes and misfires. Mercedes-AMG issued a service bulletin covering M156 engines, including later ones, and replacement adjusters put it right. A quiet start, or invoices for adjuster work, is what you want.
More known issues, covered in the full guide for each car
- Sticking injector
Cars with the M156
- Mercedes-Benz C63 AMG W204: All C63 AMG versions, 2008 to 2014, including the Edition 507 and Black Series
- Mercedes-Benz CLK55 and CLK63 AMG: CLK63 AMG and CLK63 Black Series, 2006 to 2010
- Mercedes-Benz E55 and E63 AMG W211: E63 AMG saloon and estate, 2006 to 2009
- Mercedes-Benz E63 AMG W212: E63 AMG 6.2, 2009 until the switch to the 5.5 biturbo in 2011
- Mercedes-Benz SL55, SL63 and SL65 AMG R230: SL63 AMG, 2008 to 2011
A pre-purchase inspection guide for your car
The CrankSight guide is a pre-purchase inspection (PPI) you do yourself, written for the exact model and generation you're viewing. It walks you round the car on your phone, with every check for that version, engine included: what to look for, where to find it, and what anything you find is likely to cost. As you go it builds an assessment of that car, and if you view more than one, it lines them up side by side.
£29 for the model, used on as many cars as you like, delivered within 72 hours or your money back.
General points for the engine, last checked October 2026. Every car is different, so treat this as a guide to what to look at, not a verdict on any car. CrankSight is independent and has no connection with any manufacturer.