Cracked piston on 2017 c300 coupe - M274

[ajlsl600]

Christ. Plastic gears, shite chains crxp sensors and dud pistons, jamming egr flaps . Can't those damn Germans make anything properly anymore!! Having another look at Dacia and Ford soon, at least they Don't sell the IDEA of leading quality, cost!

 

[LostKiwi]

This might be useful.

 

[ajlsl600]

This might be useful.

Interesting. Basically small end failure. Had a quick look. Do you know does this eng have skirt pin lube jets?

 

[LostKiwi]

Interesting. Basically small end failure. Had a quick look. Do you know does this eng have skirt pin lube jets?

Nothing on the rods so unless there is a dedicated spray rail ( a la m119) I'd say not.

 

[LostKiwi]

Found a few pics online. Looks like a common failure mode:

Looking at that I'd say that looks like poor piston design.
The pin and support structure sit a long way inboard of the bore leaving the lower ring lands badly supported.

 

[ajlsl600]

Nothing on the rods so unless there is a dedicated spray rail ( a la m119) I'd say not.

Is this the motor or same type if so I see 4 oil jets on epc online pts list.

 

[LostKiwi]

Is this the motor or same type if so I see 4 oil jets on epc online pts list.

It's an m274.

 

[ajlsl600]

It's an m274.

Stand to be corrected but think that's same thing. No?

 

[ajlsl600]

Think this it? Item130 oil jet x4

 

[LostKiwi]

That's not the same engine I see as m274 on online EPC. Is that the 1.6 or 2.0?
The OPs will be 2.0 but it does appear to have spray nozzles.

 

[LostKiwi]

Think this it? Item130 oil jet x4

Yep.

 

[Honey]

Apparently (from a quick Google) there is an issue with gudgeon pins knocking in the piston leading to piston failure on the M274 engine.
Personally if this is true I'd demand all 4 pistons, rods and gudgeon pins be replaced as a minimum.

The mileages for failures seem to be around 50,000 to 70,000 miles.

My car is almost at 50,000 miles

 

[EmilysDad]

My car is almost at 50,000 miles

Not exactly a high mileage car then .....

 

[malcolm E53 AMG]

As you say LK I’d want to know what MB have done to remedy the situation I suppose the stock answer from them will be it was a bad batch but the piston design does appear to be part of the problem

 

[ajlsl600]

LK looking at piston. Would say over zealous design re reduction of reciprocating weight. I don't know for sure but suspect this motor more revvy than previous eng model/s

 

[McDonald]

I've got to say, you guys know your stuff. For the umpteenth time, I'm impressed.

 

[Jim2]

Welcome Honey, and I hope that it will all work out for you !!! Should not have to endure this kind of experience in a supposedly high value car.

 

[LostKiwi]

LK looking at piston. Would say over zealous design re reduction of reciprocating weight. I don't know for sure but suspect this motor more revvy than previous eng model/s

I'd say over zealous weight reduction.
All it would need to reinforce it would be a couple of reinforcement ribs running either side of the gudgeon pin out to the edge of the bottom ring land. Best solution is a wider gudgeon pin and supporting boss on the piston but that adds a lot more weight.

 

[ajlsl600]

Some bean counter prob smelt a 10 cent saving on each piston. And over ruled any design concerns.

 

[ajlsl600]

Do wonder if replacement piston is redesign or more of same. If had time would look pt numbers. Given only one changed I suspect more of same