Considering purchasing an m278 powered w222 S550. I know early m278’s weren’t great. Also curious about what you think the best way to ensure they remain reliable for daily use (aside from regular A/B services)

 

Search this site extensively for bore scoring and turbo line leaks.

 

Change the oil 2× more often than OLM indicates.
Drive at least once a week.

 

I don't wholeheartedly agree with the 2 prior post. It is a good idea to use a car as intended versus keeping it as a garage queen, but there's no magic number of times to drive a car. You want the car to operate in optimal conditions as much as possible, so that means running it for 45 minutes where it's moving and the oil and coolant are optimal is better than 5 minutes of running with fluids cold. But it will take 5+ minutes or more for the car to reach optimal operating temps. So a long drive creates less wear than several short trips. All that means is use a car like a car...and enjoy. And there's no detriment to changing fluids more often than recommended, just extra cost and more waste.

As far as bore scoring. It only applies to 2014 model year W222's, and only motors produced prior to July 2014. Otherwise they are no more prone to bore scoring than any other car on the market.

As you go higher in age and mileage, focus more on the maintenance and repair history. Especially as you past 50K miles; the previous owners' usage will be a much higher determining factor in the car's long-term reliability than anything else. Lots of infomration on Carfax reports, and you might be able to get the VMI too. Research will be the key to finding a good car. But having said that; ask as many questions on this forum as you can think of; there' s a wealth of knowledge here.

 

They are just a complex engines like any other turbo V8 engines . I love them anyway . I have seen many of those covering more than 150K miles . Those cars are meant to be driven but maintenance is something you should never omit

 

Thanks for the info.


 

When it comes to oil changes, for most owners the MB recommended 12 mo/10k mileage A/B service interval on oil changes is wayyy to high. While the time interval may be fine for low mileage drivers, the mileage interval should be cut in half to no more than 5k miles as gas does slip past the rings and "thins out" the oil over time, making it much less effective and causing premature engine wear. If you doubt this, then send your higher mileage oil into a lab like Blackstone to be tested and find out that it no longer has the chemical composition that the manufacturer requires to protect the engine.

 

Hi Dave, I don't disagree about oil dilution, you're 100% correct about it. However, there are additives and stabilizers in the oil that diminish the effect of oil dilution. And having 9.5 quarts gives you a much higher buffer zone for oil dilution than just having 4-5 quarts. But like you, I change my oil every 4-5 thousand miles, and would suggest the same for anyone. In the vain of prevention versus cure, I'd suggest the OP focus on the car's maintenance history. You can't reduce the wear if the car hasn't been maintained properly. I guess that's my point, since the question was about reliability.

 

Hello, I've had a wonderful experience with the M278 with my older car. So much so that I picked up a later model S-class with one. I had no oil in the cam sensors or bore scoring, however, I was on top of things. I sent an engine oil sample to blackstone to get a reading, and they recommended a 7500 mile change interval with the factory oil. The bore scoring could be attributed to multiple cold starts and contaminated oil. Its important to keep the engine oil clean. Even frequent air filter changes can help as those "high-performance" air filters can bring in dirtier air. I use top tier gas to ensure that I get cleaner burns and the additives and detergents can help clean injectors and fuel lines. I am weary of any carbon buildup cleaning from the dealer. It's been pitched to me a couple times and it seems like a cash grab. Any carbon that dislodges from the piston domes as a result of this kind of cleaning could potentially score the cylinder walls as well. The best maintenance is preventative. As a previous poster stated, its very important to run the engine at operating temperatures and pressures as metal on metal contact due to a lack of oil can also cause scoring. This is why its important to run your vehicle to warm it up instead of just warming it up while static. I also disabled the start/stop. The internet can make any problem much larger than it is. Learn from peoples experience though. The engine and drivetrain in all my MB vehicles have been bullet proof.

 

@CaliBenzDriver and @S-Prihadi have done extensive research on this and many other topics in thier quest to limit having problems with their(our)Mercedes. As you will see many others have contributed to the cause as well. While they don't have the M278 or an S222 thier findings are very much applicable to many othe models. The follow 2 threads speak extensively to modifications you can make to your Mercedes to limit the risk of cylinder scoring and a host of other benefits from implementing disconnecting the oil solenoid and enhancing your oil viscosity.

While they are long reads they also provide supporting proof to the modifications.

2 stage oil pressure valve bypass

Oil pump solenoids

so in addition to regular more frequent maintenance the mods will greatly reduce your risk and your M278 will provide you much better performance at little to no extra cost.

Good luck.

 

These cars will be collectibles in couple years once only electric cars are sold.

The stock conditions lead to oiling issues that may be avoided by not following published procedures.

In addition laggy engine accelerations and tranny poor gear selection will be cancelled using W50 viscosity.
(quality ester oil do pump well at -40°!)

 

They might be collectible in 30-40 years for well preserved, low mileage cars. Kind of like the higher end versions of the W116 and W126 are now. Although most of those can still be had for reasonable money. But I don't think we'll see an all electric car market for more than 30 years. We don't have the infrastructure for it, they'll likely not get over 400 miles range out of the batteries, and the vast majority of people don't want them and never will.

 

personal transportation is going to become a membership service like cable TV with driverless cars

 

it would be great if you point out the source of that information.

Dates are important to separate :
1- timing cover gasket that allowed coolant mix with oil
2- Silitec coated cylinders to iron cast (like its M276 sibling)3- Head valve guide issue
4- check valve, and updated chain tensioners
5- incorrectly pressed cylinder 5 sleeve


On the engine operating temperature, nothing beats letting the engine warm up to its designed value before seiving at will. Even more with turbos. Nobody has figure out how guarantee the casing expands as fast as the turbine wheel from cold under hard acceleration.

 

I'm not sure if you were saying I was wrong, or just wrong about the date of the change. In any event, thanks for the date correction. The switch happened in March of 2015, not June of 2014. That's an important point to consider. Thanks!

 

Just clarify if there is another source and keep mine up to date. A lot people considering these used M278 engine, and I want to share with them known issues. I leave to each person to make their own decision.

I was close to get an used 2015 ML550v@80K, but chickened out and settle with an available 2015 ML350 for the wife. Big difference in risk and piece of mind

 

Cars to target with M278 engine number later than the cutoff from non-iron to iron liners (these are iron liner cars):

2017 W222 S 550, 2- and 4-door variants on cargurus
2017 W212 E 500, cabs only on cargurus
2017 and 2018 X166 GLS 550 on cargurus

Late M278 are still subject to normal wear and tear and usual MB issues like leaking cam magnets, cam sensors, turbo lines, etc.