Cracked piston on 2017 c300 coupe - M274

[LostKiwi]

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

Does look like there's been a redesign - the original part number has been superceded.
This is the later part. Looks to have reinforcement ribs either side of the gudgeon.

 

[ajlsl600]

So now there is one odd weight piston in this motor!

 

[Blobcat]

So now there is one odd weight piston in this motor!

Unless they fit old stock...

 

[LostKiwi]

So now there is one odd weight piston in this motor!

If ever there was a reason to demand a full set of matched pistons.....

 

[EmilysDad]

Is there that much difference between pistons these days with modern CNC machining etc?

Ooop! just read the other posts

 

[Honey]

Think as said. But get the warranty extended by them. Or failing all else you. There is a good chance that's the end of the matter. I would want a Detailed account of all work done and why, cause. Then collect info on as many other cases as poss then wait. If work carried out as factory directed. Should be end of the matter..

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

Exactly, that is why I thought it was odd when I got the message from MB about having this issue.

 

[ajlsl600]

Not an easy case. Think as per my previous. Records, documents dealer statement, warranty..
I am forming the view that Benz quietly changed the bussiness model from around 01/05 and put some distance between themselfs and longivity/quality /customer service, unless perhaps when marketing a new product.
I do wonder, in 50 yrs, will any of the Benz cars we now drive be considered as bench marks of quality when compared to Benz of 40/50 yr ago. What you guys think?

 

[LostKiwi]

I doubt they'll be around in 40/50 years. Electronic sensor failures and lack of spares will see to that. You see it already on some 90s cars where keys are no longer available.

 

[ajlsl600]

Think my clk could still be around. Not much rust and not too many sensors

 

[Botus]

scary,

VAG went through an episode of using chocolate pistons when the 1.4 first came out it was dead common circa 2006 to 2010 all there 4 cyl engines of 1.4 to 2.0 ltr had many where the pistons just wore out and rattled about burning oil.

One has to wonder after 100 years of piston engines, where a piston was one of the items that was the most durable and reliable bits in there, why they started to become problematic in modern shopping cars that we're doing anything special or even being driven hard...

 

[ajlsl600]

Cos shorter piston skirts lighter pistons in many cases to reduce rotating weight increase rpm, get more power from smaller engines and stuffing far more in them with turbos pushing things closer to ragged edge of reliability. Cost will also be there even at 5 cents of material. This wot I believe anyway.....
Go look an old lister piston about 6 inch deep. But not likely over 1500/1900rpm. Mgb 1800 piston about 4 1/2 deep and 5400 rpm generally modern engines seem to be shorter stroke as well further reducing r.m

 

[Honey]

...yes, I'd be looking to hunt down other incidences of the piston cracking and how they were treated and if other's played up post repair.

does it run as nicely as it did ? just as smooth no strange noises or vibrations?

I guess it must be fairly common or the repair wouldn't have been just the piston.... usually they would just swap the engine over, so I guess it won't be the first one they did like this and they know its OK.

4 years 50k miles seems odd?
3 years and 60k miles more usual

I would get extended Mercedes warranty... even if you have to buy a big service and pay out for the warranty, both together could be £900 but that is still a bargain to get the piece of mind for a further year.... ( you can more or less exchange £ for $ these days)

other non merc warranties would claim the earlier repair means they aren't paying out.... and a new engine if it did come to that in the next 12k miles would be in the region of 7 to 11 k out of your pocket (so its an utter steal for the piece of mind)

https://www.mbelcajon.com/new-vehicles/ that's a long way from here...

Thank you

 

[Honey]

Yes, my son pays circa £700 a year for his extended warranty to cover 20k miles pa. I would imagine you will be offered a 1 year warranty on the repair and could pay to extend during your ownership. You may be able to negotiate a better deal no harm in trying, good luck with it and you may be worrying unnecessarily the repair may be Your probably right. Thank you for responding.

 

[LostKiwi]

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.

 

[Honey]

...yes, I'd be looking to hunt down other incidences of the piston cracking and how they were treated and if other's played up post repair.

does it run as nicely as it did ? just as smooth no strange noises or vibrations?

I guess it must be fairly common or the repair wouldn't have been just the piston.... usually they would just swap the engine over, so I guess it won't be the first one they did like this and they know its OK.

4 years 50k miles seems odd?
3 years and 60k miles more usual

I would get extended Mercedes warranty... even if you have to buy a big service and pay out for the warranty, both together could be £900 but that is still a bargain to get the piece of mind for a further year.... ( you can more or less exchange £ for $ these days)

other non merc warranties would claim the earlier repair means they aren't paying out.... and a new engine if it did come to that in the next 12k miles would be in the region of 7 to 11 k out of your pocket (so its an utter steal for the piece of mind)

https://www.mbelcajon.com/new-vehicles/ that's a long way from here...

The car also has had a

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.

Good idea, thank you. I will definitely ask!!

 

[Honey]

So now there is one odd weight piston in this motor!

That is what I thought too

 

[Kev555]

Looks like a clear cut piston design flaw if that's the new replacement piston LK posted

 

[Botus]

unless the car runs different pistons in each cylinder as std (which is not normal), it would be outrageous to only fit one later modified piston (I had not seem LostKiwi's post re a modified type at the time I first commented).

Once they are at the level of strip down to fit a new piston, it would be little more work and not much more costly to replace them all (as you would expect). And thus the likelihood of failure and the engine running badly would be far less.

I suspect they would have fitted 4 new pistons. You need to see the parts list for the job they did... I'd make sure this is on record and that you get support by contacting Merc customer services. One later piston would be a bodge from a corner garage on an old wreck, not a reliable fix by a manufacturers approved repair centre.

 

[Honey]

unless the car runs different pistons in each cylinder as std (which is not normal), it would be outrageous to only fit one later modified piston (I had not seem LostKiwi's post re a modified type at the time I first commented).

Once they are at the level of strip down to fit a new piston, it would be little more work and not much more costly to replace them all (as you would expect). And thus the likelihood of failure and the engine running badly would be far less.

I suspect they would have fitted 4 new pistons. You need to see the parts list for the job they did... I'd make sure this is on record and that you get support by contacting Merc customer services. One later piston would be a bodge from a corner garage on an old wreck, not a reliable fix by a manufacturers approved repair centre.

Thankyou that is great information

 

[ajlsl600]

In the event that only one, different piston was fitted (unlikely, but. Possible) and you can collect evidence I would say that a great point to start looking a replacement engine.. I have certainly never come across such an incident previously outside the third world.