Cracked piston on 2017 c300 coupe - M274

[Honey]

Honey,
See if you can get a picture of the failed piston showing the area where it failed.
I'd be very interested to see if it's the same failure as the others I found images of.
I'm pretty sure the dealer won't allow it but try anyway as it may help someone else in future.

Hi, I picked up my car from Mercedes and asked about getting the parts that they replaced and I was told since the vehicle is still under warranty they have to send it back to the manufacturer. I will attach the report they gave me. Unfortunately the car is still shaking at idle and smells like something is burning when i turn off the car and get out. To top off this whole experience when I was getting into my car and saying goodbye to the service adviser I noticed a nice big crack in my windshield. They said they would order a new windshield and to being my car back next week. I confirmed yesterday that they ordered the windshield and told them about the shaking and burning smell and they said they would just address it when I come in for the windshield repair. I hope they don't charge me for that windshield.

 

[LostKiwi]

Do you know what they replaced?

 

[Honey]

Hi, My 2017 Mercedes C300 coupe broke down recently. Started to jerk and lose power and white smoke was coming out the exhaust pipes. So I had it towed to the dealership. This is what they said

"Mercedes"-Hey Honey, so looks like your probably going to need a new engine!! Still confirming but looks like one of the pistons cracked. You're under warranty so its totally covered. I should know for sure in the next day or 2 but plan on keeping that loan car for awhile, may be a couple weeks

"Mercedes"-Honey just wanted to give you an update. It turns out they don't have to replace the whole engine. They are replacing the turbocharger and they have to replace one of the the pistons.

"Honey"-Hi Dan, thank you for contacting me. To be honest I do not feel confident in that repair. What kind of warranty is Mercedes willing to put on the engine once the repair is performed. There could be underlining problems as a result of that day when the car broke down. After some research and speaking with the other service centers "SD Mercedes, MB El Cajon" I would feel more confident and safe to have that engine replaced. (MB El Cajon said they are replacing one of those engine a week ).

"Mercedes"- I understand but nothing is wrong with the engine. We replaced the engines sometimes as well but in this case there is no damage to the cylinder sidewalls so there is no need to replace the whole engine, only the piston was cracked. That does cause underlying damage to the turbocharger as well which is why we are replacing that too. Unfortunately mercedes makes dealerships prove every warranty repair we do is needed so they will only allow us to replace what is damaged. The warranty is the same 4 year 50,000 warranty that came with the car at time of purchase, no extension or anything when a warranty repair is done

"Mercedes"- Basically one of the pistons cracked, which is why you had so much smoke the oil got through and it was burning oil. So we inspected for any damage in the engine, there was no other damage other than the piston being cracked. We replaced the piston then also the turbo charger and the catalytic converter due to all the smoke and burning oil. Refilled all the fluids and everything then test drove and all is good. The technician has his report on the paperwork as well with much more details on what he did (little over my head lol).


What should I do? Should I be getting a new engine since that is the remedy at other mercedes service centers?
Thank you

~Update~
I picked up my car from Mercedes and asked about getting the parts that they replaced and I was told since the vehicle is still under warranty they have to send it back to the manufacturer. I will attach the report they gave me. Unfortunately the car is still shaking at idle and smells like something is burning when i turn off the car and get out. To top off this whole experience when I was getting into my car and saying goodbye to the service adviser I noticed a nice big crack in my windshield. They said they would order a new windshield and to being my car back next week. I confirmed yesterday that they ordered the windshield and told them about the shaking and burning smell and they said they would just address it when I come in for the windshield repair. I hope they don't charge me for that windshield

 

[Honey]

Do you know what they replaced?

 

[LostKiwi]

Disappointing they only replaced one piston. What warranty are they offering on the engine?

 

[ajlsl600]

Is that piston number same as original. Or modified pt. I see a con rod and bearing too. Who would open an eng and just change one.bearing. .
Anyway as LK what warranty has been given. If I broke customers screen I would let them keep loaner till it was replaced.

 

[Kev555]

Wouldnt matter to me what warranty was given. You cant make a silk purse out of a pigs ear. Was a bit concerned about them not finding broken off part of piston? it could have disintegrated into the oil or in the old turbo but still

 

[Botus]

the car is still shaking at idle and smells like something is burning when i turn off the car and get out.

the smell could easily be a result of the work and should burn off
the roughness / shaking is much more concerning

I would open the bonnet (hood !) and take a video, if its bad the engine will be wobbling about. could do both from cold start and after a run.... then maybe compare to another with the same engine and transmission to see if its the same

if you can feel this is "very" different to before the breakdown, then I would pursue the garage as its not been correctly fixed

the broken screen may have been there? very hard to prove and depends on the condition cleanliness of the car when you dropped it off. It if was very clean and you are adamant the screen was not broken and its now very obvious, wait and see if they ask you to pay? if they don't they knew they did it and were just trying it on....

its not a great experience, I have to say. I would expect MBUSA to be slightly interested in hearing about it / offering you some support from a customer experience perspective... they may step in on your behalf to try and up the game of the garage who seem to have been a bit sloppy. As for MBUSA try and get a technical guy to explain why ONE PISTON with an updated part number is an approved repair (check that part number now you have it)

 

[LostKiwi]

Is that piston number same as original. Or modified pt. I see a con rod and bearing too. Who would open an eng and just change one.bearing. .
Anyway as LK what warranty has been given. If I broke customers screen I would let them keep loaner till it was replaced.

It's the later part.


Just mentioned this to my other half (buyer for Jaguar Land Rover) and she was surprised they only replaced one piston. Her immediate response was "Why didn't they replace them all? You can't replace just one".

 

[ajlsl600]

That and one set of shells. If was us Benz would prob say you Have to buy all 4. Frankly I would get the best Benz warranty on work and sell car on.

 

[Botus]

If you believe it now drives worse than before the breakdown (rough running), it could be worth renting or going to another dealer to test drive one they have secondhand - in the exact same spec (engine, gearbox and similar age / mileage) and comparing side by side on the same day, just to reassure yourself.

maybe ring another Merc dealership (and get a technical bloke or even the parts guys) and say I have a broken piston ( I hear its quite common and there's now an updated part) and ask what's the correct repair method...

in some markets they have a "dealer principle" who carries a lot of clout and is the person to escalate issues to - if you like the fight they probably have one for sale, get the dealer principle to agree they need to get someone from MBUSA technical with you and both cars and get them to tell u how yours is OK …. start documenting the time you have spent on this, each post here and exactly what issues you have with the repairs / damage to the car, incorrect info the garage have given you. Get a timeline with time and dates, a list of phone calls, letters, emails...

 

[Honey]

If you believe it now drives worse than before the breakdown (rough running), it could be worth renting or going to another dealer to test drive one they have secondhand - in the exact same spec (engine, gearbox and similar age / mileage) and comparing side by side on the same day, just to reassure yourself.

maybe ring another Merc dealership (and get a technical bloke or even the parts guys) and say I have a broken piston ( I hear its quite common and there's now an updated part) and ask what's the correct repair method...

in some markets they have a "dealer principle" who carries a lot of clout and is the person to escalate issues to - if you like the fight they probably have one for sale, get the dealer principle to agree they need to get someone from MBUSA technical with you and both cars and get them to tell u how yours is OK …. start documenting the time you have spent on this, each post here and exactly what issues you have with the repairs / damage to the car, incorrect info the garage have given you. Get a timeline with time and dates, a list of phone calls, letters, emails...

Thank you so much!!! Great info.

 

[Honey]

It's the later part.


Just mentioned this to my other half (buyer for Jaguar Land Rover) and she was surprised they only replaced one piston. Her immediate response was "Why didn't they replace them all? You can't replace just one".

Exactly

 

[bembo449]

Im astounded they haven't road tested the car after repairing it , sure should br standard practice??

 

[John Laidlaw]

I'd agree on the road test, incredible- also annoying they didn't find the missing bit of piston.....

 

[Kev555]

I am quite sure they did road test unless it was running that bad in the workshop that they allowed there was no point in road testing. Either way they cleared it out of workshop as it was taking up valuable space and time for more lucrative work since they had probably used up all the Mercedes allocated time on the job if same as other manufacturers warranty goes. They might sort it out in next visit as it possibly will be allocated more time from Mercedes warranty as it will be logged as a new and separate issue under warranty. Screen could be a different haggle unless they admit responsibility for doing it.

 

[Botus]

I wonder if it had its emission stuff done... and whilst rebuilding the software adaptions it was a bit ill at ease ?
would be nice to hear how it panned out in the end....

 

[brandwooddixon]

Found a few pics online. Looks like a common failure mode: View attachment 58511

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.

Jeez. Not a lot of metal in that. I'm horrified. I know that it means for reduced moving mass, but still.

Reading the rest ... they only replaced one piston?
Isn't that going to put the engine out of balance if the new pistons are heavier than the old?

The burning is smell at the moment is likely to be grease on the exhaust burning off from it being handled, it shoud stop doing that after a few days of motoring, but the shaking and vibration is another matter.

 

[Sehnsucht Berlin]

I am not sure if the forum rejected my post that I made a few days ago but long story short I had the exact same situation happen on my 2017 C klass (despite it having excellent service records) and less than 54,000 miles on the odometer.
I am done with Mercedes-Benz, even after I attempted to contact MB customer service to file a good will claim (both times) MB refused to provide any assistance for my car. The repairs of the engine (assuming no other parts were damaged) are well over 15,000 (EURO). For obvious reasons the car is essentially totaled out. I contacted a local German motor authority office to file a complaint (and request an investigation into this matter).
As of yesterday I placed an order for a White Lexus LS300. I will NEVER drive another POS MB ever again!

 

[Blobcat]

I am not sure if the forum rejected my post that I made a few days ago but long story short I had the exact same situation happen on my 2017 C klass (despite it having excellent service records) and less than 54,000 miles on the odometer.
I am done with Mercedes-Benz, even after I attempted to contact MB customer service to file a good will claim (both times) MB refused to provide any assistance for my car. The repairs of the engine (assuming no other parts were damaged) are well over 15,000 (EURO). For obvious reasons the car is essentially totaled out. I contacted a local German motor authority office to file a complaint (and request an investigation into this matter).
As of yesterday I placed an order for a White Lexus LS300. I will NEVER drive another POS MB ever again!

You posted the same message on 2 threads so they were merged into one