I'm looking at purchasing a new to me Mercedes. At first I was intrigued at the M156 because of the power output of a naturally aspirated engine, but from what I've seen and read this seems to be a Mercedes Benz disaster. The head bolts are repairable but all the other issues just seem like this thing is an inevitable grenade.

 

AMG V8s are generally grenades.

M156 has head bolts and soft cam lobes to watch out for, plus other less severe issues. If engine replacement or major rebuild is in your budget, go for it. If not, watch out.

 

Why is needed the engine repalcement only for the cam lobes or for the head bolts ?

 

Not an expert, but I have about 96k on my 2010 E63. No serious problems yet. I’ve had the valve covers off and the cams looked ok at about 85k. I am getting some roughness now that’s telling me that my mounts may have gone and some rattling on cold start that is reportedly a common issue. Overall I’d say that it is a relatively maintenance intensive engine and would agree in principle that if you won’t be in the position to drop a few thousand into the engine, you might want to shy away, especially if you’re going to be paying someone to do everything (so far I’ve done all the work on mine but not sure I want to jump into the cams or headbolts myself).

 

M156 head bolts and soft cams = major repair

M157/M278 cylinder scoring, chain related problems, oil in harness and valve guides = engine replacement (scoring) or major relair (guides, chain, oil in harness)

M17x seems to be avoiding scoring, piston cracking and bad valve guides so far, but it’s early for this engine.

 

I have 2011 E63 and I’m coming up on 158,000 miles. The engine number was after the head bolt issue was addressed. The camshafts/lifters were replaced under warranty around 83,000 miles, as was the transmission. Engine mounts were replaced around 100k miles. Had purge valve replaced before that. Also had thermostat replaced due to coolant leak. Had fan belts replaced after the thermostat. Steering fluid reservoir was also replaced due to leak. Recently had the radiator replaced and the coolant reservoir replaced for leaks. Rear tires last about a year and I seem to have gone through 2 sets of brake pads per set of rotors. My sunroof is a tad creaky sometimes and the active side bolsters in the seat are leaking. It’s a phenomenal car and I have zero regrets about it.

 

It’s a phenomenal car and I have zero regrets about it.[/QUOTE]
After all this is the best Mercedes-amg engine of all Times