Piston guided connecting rods are the Achilles heel of the M157. Tasos even has a video talking about it somewhere. Big torque spikes from small turbos and unstable rod design is a recipe for bent rods.
It's unfortunate because all other aspects of the engine geometry (bore/stroke/rod ratio) are favorable for supporting big power.

I am going to upload photos of the engine and internals once it’s all stripped down. I had this aggressive setup for three years now and have covered precisely 31k miles before this happened. I never did any drag racing, maybe a couple of times. Mostly I used the power on autobahns pulls, which, as exactly Tasos described, is the worst for for the engine.

My mechanic only thinks that I bent my rods, simply because the symptoms are there. The question rather is how many rods I’ve bent, whether cylinder walls are gone. When we briefly started the car, lot’s of white smoke, very significant smell of oil coming from the exhaust, rough idle and revs going up and down, blinking check engine light.

When the event happened I was doing WOT, speed about 120-140MPH, it was supposed to engage 5th gear, but did not, instead, there was some mechanical noise coming from an engine, all lights on the dashboard went on (never seen anything like that before) and white/blue smoke came from the exhaust. Also, the oil went up through the oil cap - see photo. Revs went up and down and engine shut itself down.

keep us posted . Also I want to point out . Anyone with higher flowing intakes please make sure your pcv system is operating properly. You have to make sure during wot your block is releasing the pressure through the pcv into the turbos. Sometimes High flow intakes take away the vaccum the pcv needs to receive in order for the check valve to open allowing the crank case to release blow by pressure . Please check for that ghost code . It will say something like . Pcv not operating properly during Wide open throttle.

corrct . These blocks are actually amazing imho. Look at the amount of tq they handle . How many motors do you know that can handle about 1000 ft lbs of tq stock. They absolutely over built this engine to withstand power . The problem is now we are far beyond what it's rated for . Open deck design tends to rock the cylinder walls during high loads as well . These block sleeved which now make it like a closed deck but with open deck cooling with better internals is an absolute bullet proof setup. You can run 900 hp all day every day.

More updates will be over here: https://mbworld.org/forums/w212-amg/...ence-m157.html

I'm currently on 66k miles with my 2014. I bought the vehicle tuned/modified. Previous owner applied the mods. My guess is it has been tuned for about the last 10k miles.

I have a similar as setup yours. Stage 2 w/catless downpipes. No TCU tune though. Running stock plugs and stock gap as well. I haven't dyno'd it myself but according to the previous owners dyno chart(600 awhp and 735 awtq), this thing is making 750hp and 920 lb-ft of tq at the crank(if you do a 20% drivetrain loss conversion). That is a crap ton of power. This thread scares me.

I mean, but us that have tuned this engine know it wasn't really "safe" right? The engine wasn't designed for this .. Over engineered a bit, but not designed for this. We pay to play - sadly sometimes paying means a new engine. I get that when I fire it up everyday.

The more I read on here the more Im scared of flooring mine.. Maybe it's best I go back to my routes of n54, where a built motor costs 4-6k and not 20k+

Watch this:

And watch this from 15:40

Meh
FLOOR IT!!!!!!
Or go buy a Camry.

Here's the video where he explains the M157 having piston guided rods. Starts at 0:50s.
In most engines the connecting rod is guided by the big end bearing which has a much larger surface area compared to the wrist pin and able to keep the rod from rocking. For some reason on the M157 Mercedes decided to use a piston guided rod setup which allows the rod to "rock" under some situations. Probably the reason why these engines bed rods easily and why there are many cases of cylinder scoring. The material of the rods themselves is plenty strong to be able to handle a tune with stock turbos if they were crank guided.
My theory is that when BMW came out with the F10 M5, Mercedes couldn't compete with the N/A M156 E63 and they needed a turbo motor to counter. The M177 was probably in early development and wouldn't be ready in time so they resorted to modifying the M273 architecture to create the M278/M157 as a temporary answer until the M177 was ready. The M273 4.7 and 5.5 variant share the exact bore/stroke as M278 and M157, same open deck block, and same piston guided rod setup. The M177 is a much more robust engine, designed for turbocharging from the get go with a closed deck block, nanoslide ferrous sleeve coating, crank guided rods, etc. Just my $0.02.

Well, I don’t generally post but my car seems like an outlier.
2016 s63 coupe, bought new.
drove it hard totally stock till 100k miles, extended warranty ran out, with no problems, just doing routine fluid changes, lots of tires, and several sets of brake pads.
at 100k miles, had the weistec tune stage one, cooler plugs, air filters.
continued routine fluid changes.
very sensitive to crap ca gas, would always add a couple gallons of e85 or a bit of Boostane to avoid the knock in hot weather.

developed a misfire cylinder 7 abruptly at….. 219,000 miles.

Limped it home, changed injectors, plugs, coils.
no better.

quick and dirty compression test shows #7 with only 60psi, neighbors have 90 plus.

will scope it at some point, trying to decide what to do next. Was my dd. Replaced it w a Trx (till the new sl63 hybrid arrives I think )

have to get some more info, to determine if it’s a ring issue, stuck valve, etc. no loss of mileage, oil looks clean, no loss of coolant, doesn’t overheat, no smoke.

these engines are amazing.

even if I just junk the car, it has been money well spent.
otherwise, maybe used motor swap, if it’s just a valve, maybe just do the head on that side?

220k miles with 120k w a 700hp tune? And that’s in both stop and go SoCal traffic as well as being hammered on when there isn’t traffic.

Can i ask you how do you maintain your AMG ? Oil change intervals and other fluid maintance ? Im ready to purchase a one owner 37K miles 2015 s63 but i am waiting PPI results. The internet and my searching online has increased my fear of cylinder scoring and what not. Im not scared of the cost to upkeep an AMG but i dont want it to go to waste under my ownership. Any advice ? Thank you.

oil change every 5k miles, plugs every 10-15k, coils every 20k, all the other usual things, recommended maintenance.

what is the most you would be willing to invest in this car over the next 5 years of ownership? Consider this thread:

https://mbworld.org/forums/w212-amg/...-oil-leak.html

thank you for your answer.

realisticaly i am looking to own the car for 1year to a maximum of 2 years spending 7-10k.
i am willingly and prepared to spend on what you mentioned above: oil,plugs,coils,tires and pads at moment of purchase and again at mentioned above intervals.
car will be more of a weekend sort of special occasion.
I plan to put a maximum of 10k miles. Car will be sold at a maximum of 50k miles.

Have owned a 2017 cls63s briefly( 7 months) i am aware of maintenance cost, bought one owner at 29miles. Sold cause someone made me a offer I couldn’t deny.

But having researched a lot this time around I’ve created the impression that the m157 is not the reliable powerplant I believed it to be.

After reading a bit in the thread you linked sums like 30k are getting to my head.

Did the engine undergo any updates during its life span for some of the more severe issues? Are there safer model years to go after ? I am thinking about this specific car as it comes equipped with everything and spec is to my liking.

Thank you for your time and expertise.


Engine 157985 60 049637
Release Date 2014-04-03
Model Year 2015

See above

Just went to 90k. Bought car at 78k. High miles but i was very paticular about options and color. Tuned by jerry for the last 10k miles.
driven on stage 2 e47 tune for maybe 1k miles.
mostly just driven on stage 1 regular fuel.

Live in NY.
bosch indexed and gapped spark plugs to .22 or .022.
oil- motul 8100 0/40
creative steel engine mounts. Stock transmount
changed oil level sensor and all camshaft sensors. Wire harness for cam sensor and magnets.
Diff fluid changed


only service i have not done is the tranmission fluid and fixed lower control arm. Off center but not horrible.

what software can i use to monitor engine?

Sry to hijack . Oil level sensor failed ? or just afraid it could be an oil wicking point .. Not a bad idea, haven't seen alot changed out thus far.

They tend to fail. Mine failed at 19k. Just stopped reading oil temps, that's it

Had a mess of oil in that area. Maybe the o ring went bad. I saw on here to just change it, so i did. I keep my cars for a while and this car was used so, im just changing things as i go to limit any issues later. STILL HAVE MY e46 330I ZHP and e60 535xi LOL. im almost getting kick out of the house lol. Have to sell one of these fml.

Also very scared or oil wicking. When i unclipped the sensor it was dry. Thank god.

do you still have the car? how many miles does it have now? and what issues (if any) did you face with it?