W205 C300 - stay away. Piston cracked at 65 K miles.
I'm with benzdude, this thread IS scary!

Last edited by benzdude; Oct 14, 2021 at 11:15 AM.
I would expect a battle though.
Mercedes won't pay for this... and this is going to cost me $10,000.... for a car that's fully optioned and MSRP at $52,000K this is pathetic. I will never buy a mercedes again.
Mercedes must stand for this wrist pin issue or i will start a LAWSUIT.
The Best of Mercedes & AMG
Note how the crack doesn't appear to exist in the topmost edge above the top ring. To me it looks like the combustion chamber surface has not been compromised.
The crack appears to either emanate to, or have emanated from, the wrist pin. Because the crack doesn't happen when the car is driven off the showroom floor, it is a fatigue (cyclic stress) crack in my view.
Do you have the piston in your possession? Can you post photos of the underside, facing the crankcase? And photos of the top surface exposed to the combustion chamber?
"Hot tune" as some have speculated to be the root cause is not ruled out. And it is not ruled in. Inferior piston design (my opinion for the root cause) or a bad quality batch of pistons from the supplier (not the root cause in my opinion) could fail as pictured, hot tune or no hot tune.
Note how the crack doesn't appear to exist in the topmost edge above the top ring. To me it looks like the combustion chamber surface has not been compromised.
The crack appears to either emanate to, or have emanated from, the wrist pin. Because the crack doesn't happen when the car is driven off the showroom floor, it is a fatigue (cyclic stress) crack in my view.
Do you have the piston in your possession? Can you post photos of the underside, facing the crankcase? And photos of the top surface exposed to the combustion chamber?
"Hot tune" as some have speculated to be the root cause is not ruled out. And it is not ruled in. Inferior piston design (my opinion for the root cause) or a bad quality batch of pistons from the supplier (not the root cause in my opinion) could fail as pictured, hot tune or no hot tune.




https://daydaynews.cc/en/car/399645.html
https://m.carcomplaints.com/Mercedes...e/engine.shtml
Last edited by JCM_MB; Oct 17, 2021 at 10:47 PM.



i bought my 2015 w205
min October 2018, with 53k miles
im now at 115k miles.. wrist pin issue was a thought at one point.. but it was the alternator
coupling making a clacking noise..
how would i check when my car was made?
Bought the car new, special order, built in Germany took delivery 5 years ago. Out of warranty 72k miles.
Having dealer install rebuilt long block n turbo - some financial help from the dealer but still over $8k to repair - disgusting. I wish I knew about the problem before the standard warranty expired - I was getting different dealer quotes for the extended warranty- nobody mentioned issues with the engine - decided not to go with the extended warranty ( huge intake in hindsight).
Last edited by martinsw; Oct 28, 2021 at 01:53 PM. Reason: Typo
Last edited by mmateo; Oct 28, 2021 at 09:54 PM.
Bought the car new, special order, built in Germany took delivery 5 years ago. Out of warranty 72k miles.
Having dealer install rebuilt long block n turbo - some financial help from the dealer but still over $8k to repair - disgusting. I wish I knew about the problem before the standard warranty expired - I was getting different dealer quotes for the extended warranty- nobody mentioned issues with the engine - decided not to go with the extended warranty ( huge intake in hindsight).
I have noticed that the engine sounds very clattery but I assume it's because it's a direct injection motor. I suppose enjoy and hope for the best!
I just did a quick search looks like there are aftermarket forged pistons - maybe worth a look if you're fixing out of pocket: https://premiumtuning.hu/products/wo...274-11910.html
Last edited by Holson; Oct 30, 2021 at 06:03 PM.
I had at least 5 MBZs in my past and more in my family members, never had this experience of Check Engine Light repeating and SHAKING engine, while under busy traffic commutes.
I don't even want to go to dealer and get my *** bend over to MBZ dealers........ they are nothing but making $$$$$ from innocents loyal customers whom had given them repeated business.
I don't know what to do next. I still owned 4 others MBZs and those cars never had this serious issues.
park right outside of MBZ dealers to set on fire on my worthless C300 to boycott and get attentions from MBZ factory to paid back all the troubles they had caused to innocents customers.
was thinking of trading EQC, but "F" ....MBZ for now, NEW EQC might NOT even better than Toyota's Plug-in Prius.
colorful BIG *** screen doesn't mean anything, when my engine is shaking worst than diesel engine......enough SAID!!!!!
I'd never believed in this kind of extended warranty......all my older 5 MBZs that I'd still owned fixed by independent mechanic shop who know MBZ. for over 200k or 300k miles on the engines without any cylinder CRACK.......
this is SICK...







I might lease one instead.