Camaroguy72

Seeing a surge of engine failures/piston cracking and curious on the following for those that have had the issue in the US

M274 engine specific in the :
2015-2018 w205 C300
2017-2019 w213 E300
2016-2019 x253 GLC300
SLC300 R172

If you've had the piston cracking issue (different from the wrist pin loose tolerance issue with the known SB on the early w205's), can you reply with the following?

1) What vehicle year/model and mileage at the time of the issue
2) What's your oil change frequency? The standard 10k mile interval?
3) Is your car subject to severe usage (short trips less than 10 miles frequently, hilly areas, extreme temps)
4) Have you had an induction service done prior to the failure?
5) Have you run any fuel additives prior to the failure?
6) Have you always used top tier fuel at 91 or greater octane?
7) Is your start/stop working normally at the time of failure?
8) Has your engine air filter been changed @50k miles/ prior to the failure?
9) Have your spark plugs been replaced @ 50k miles/prior to failure?

mobster600

This seems like a ton of BS that a dealer would try to blame you for a manufacturer fault. Don't believe any of this crap. The manufacturer is to blame for this sort of issue. Why do Honda's go 200-300k miles? Good manufacturing , engineering and parts, plain and simple. You think every Toyota and Honda gets meticulously maintained? Hell no. Tell MB to shove it and pay for a new engine if you get a catastrophic failure. Knock on wood over here of course 😀

Camaroguy72

this is just research. Mine are fine.

you think Honda’s these days are any better? Do some research lol.

mobster600

I actually heard the new Honda engines had cases of gas getting in the engine oil. I drove the new 2.0T accord it was pretty fast. But for 37k no price negotiation, this was summer 2020, they had plenty of stock BTW. It's a little over priced.

glojo

You are giving advice, plus expressing an opinion so is it fair to assume you have expert knowledge of this issue?

Is it really a Worldwide problem and judging from your opinion that answer would be yes but is it?

mobster600

A piston cracking would most likely be from poor manufacturing. OR extreme temperature changes. If it was negative temperatures and you hammered down the throttle right at start up for a sustained period of time.... maybe. Its just hard for me to believe a moderately thick piece of metal to suddenly crack from normal use would be anything but a manufacturing fault. SO yes its possible but anything is possible. To jump to the wrist pin issue, lubrication channels can be blocked to vital parts of the engine if you dont change your oil frequently.

I personally run my engine for the 10 min remote start when its below 32 F or 0 C. I do oil changes at the recommended interval. Lets say you drive alot, get an oil change before the interval.

You can prevent issues from happening if you maintain your cars. BUT to my point, anything is possible, yes a piston can crack but its most likely not your fault.

chassis

Pistons can easily crack under a variety of scenarios. The metal is actually quite thin from the piston face to the first ring groove.

Potential causes, not yet confirmed which is the real one:
- poor piston metal alloy used (non-conformance by supplier)
- poor piston casting conditions (pouring error, die failure, temperature regime, quench/cooling) by supplier
- poor piston machining by supplier
- poor geometric design by MB or poor alloy choice by MB
- "hot tune" by MB causing too much pressure and temperature in the cylinder

Mercedes' fingerprints are on this, and there is a smoking gun. The M264 engine is descended from piston cracking M274. There are a large number of components shared between older M274 and the current M264, but mysteriously the pistons have been updated.

ygmn

My guess is more **** poor design

chassis

The failure seems to be reported frequently on the #1 cylinder. This rules out in my view a quality defect from the supplier. The pistons aren’t unique part numbers for each cylinder.

This leaves, no surprise, the culpability with Mercedes-Benz. Remaining known potential causes:

- poor geometric design and tolerancing of the piston by MB
- poor metal alloy and heat treatment choice by MB
- hot tune which stresses a piston not capable of handing the tune by MB

The three points above are linked. The first two (design choices) are required to meet the demands of the third (the tune: the environment which the piston needs to withstand)

It could be that the temperature, pressure and air/fuel/coolant flow microdetails are sufficiently different in cylinder #1 to create conditions the piston cannot withstand.

trygve11

I operate a specialty shop in Kansas City (Royal Autowerks) and just bought a 2016 C300 with 68K on it from a client with the loss of compression on cylinder #1 and will perform the detailed teardown (and rebuild ultimately). My client has registered for this class action lawsuit. I recommend that anyone that has had the same concern, reach out to the CA law firm that is pursuing the class-action suit.

https://www.classaction.org/news/mer...ng-m274-engine

I am a former Ford engineer and MIT mechanical engineering graduate (Masters and Bachelors). I have also been a mechanic for 39 years. I have engaged the law firm and will likely end up being the engineering and mechanical expert on this case.

I encourage you to get registered for the suit if you have suffered a loss. Do this before you dispose of the vehicle.

- Jason

chassis

Good information to be aware of.