rocketray_

Hi guys,

Since Summer I got a heavy metallic knocking sound from the left cylinder bank on the engine. (M278, Biturbo V8)
Car was already by MB Dealer for checking - they seemed to be surprised by this noise and had absolutely no idea - but - already wanted to tear down the whole engine for a fortune.

The metallic knocking is especially from inside the cabin very loud and can be notices under acceleration - on the freeway at about 80 there's no sound anymore.

Info:
Engine oil was flushed twice since summer - once 5W-40 and testwise a 15W-60.
Felt also to give Lucas Oil Stabilizer into the engine - no dampening or change of sound.
Compression on all cylinders is good - power delivery is also good - no lack of power.


I attached a video from someone with the same problem.
Would be nice if there are some good answers to this problem. It drives me crazy. Even don't want to move the car anymore.


Thank you

number_one_c55

What was the result of this noise? We have a GL63 with same noise.

Tom Tomy

did you solve the noise issue ?
Wondering what the heck is that noise come from .
tensioner or adjuster??

number_one_c55

Engine, noise is piston rocking back and forth in cylinder allowing for noise and cylinder bore score. My shop is installing the replacement engine next week.

holidaycontrol

I'm really curious how this happened, how would a new engine/car have a rocking piston? This is quite concerning.

GettingThere

What year is your car?

number_one_c55

The piston skirts are extreamly short by design, with high cylinder pressures from being direct injection plus turbocharged the rotating assembly is already stressed plus a GL being a 5000+ LB vehicle.

Piston skirts are short for fuel economy. Less drag within the rotating assembly. Mercedes has designed these 157 and 278's to be 200,000km engines.

holidaycontrol

Incorrect, this engine is completely bulletproof - it was in the (2010+) GL550, S550, SL550, G550, E550 and CLS550 among other models and there have been no reports of this (piston issues) or it would be ALL over the forum.

That's why I am curious as to what this is or how this failure occurred. I imagine it was a timing chain slippage, abused engine or one off and bad from the factory. What are others thoughts on this?

number_one_c55

I appreciate your input but for where we are located in the world and what MB has told us during tech training. We have issues with them. The vehicles still being fairly new there is a lot of information that has not surfaced to public knowledge yet and is still retained at a internal level.

You are correct in stating your E550 engine and the 2010 engines are reliable as they are a different engine.

holidaycontrol

With all due respect sir, are you a Mercedes mechanic? Today alone, I spoke with 3 techs from the team leader to the manager of maintenance (who I know personally). Their privately owned dealership has not seen even one engine failure of any M278 (G, SL, S, E, CLS, GL class) bi turbo engine aside from some issues with timing chain issues with the earlier models and also fuel injectors.

I also cannot find one other post other then this one with a M278 engine with failure due to piston play issues. There are common issues with oil cooler, oil leaks, valve cover, front diff seal leaks, timing chain (again early 2011 models), fuel injectors (again early models) and some other problems but not one report, post of an engine failure due to a piston. These engines/motors and vehicles are now exceeding 8+ years old of various models with some (300,000KM+) now in forums/databases.

The AMG's (M157) have problems that I see all over various forums and even MB techs I talk to. They have timing chain, valve, early camshaft wear, headgasket, piston and other various problems but the M278 seems pretty bullet proof. I'm going to have to call you out on this and ask to provide some proof.

number_one_c55

Yes dealer tech from May 2008 until 2019. What part of the world are you in? We have had 3 now at the dealer and 1 including my own vehicle. No need to get upset. But the days of the bomb proof engines are gone unfortunately.

Good example would be the 642 engines. We again have issues where I am. But talk to the guys in the southern states, they have a fraction of the failures we have. Driving style, location, ambient temp how the engine is loaded upon commutes all are taken into account.

holidaycontrol

Thanks for your quick replies because this information is quite useful and I am now "second guessing" my purchase if what you are saying is in fact correct and you were a dealer certified tech which it sounds like, you were. I own a 2014 CLS550 now 4 matic.

I am from Oakville area. So what you're saying is this a ticking time bomb, could last 350,000 or 35,000KM? You saw 3 failures at your dealer? What mileage? What models?

Thanks man.

number_one_c55

Just remember, being a dealer tech and now specializing, I will always have a MB product in the driveway regardless of its reputation or issues.

What vehicle did you end up buying?

holidaycontrol

2014 CLS550 4matic, 65,000KM

number_one_c55

Beautiful, you have nothing to worry about. Very good cars.

holidaycontrol

Whew okay thanks! lol

Romann001

Hi, I have to writte a litlle bit about these engines..I am from europe(czech republic) and we have many discussions about engines M157 and M278.
Unfortunately there is a problem with them and so far I had not found what is the main reason, that car, which cost over 100 000 euros, has inside the engine after 100 000km someting like in the picture below.


cylinder

Piston

Romann001

There is maybe problem with oil lenght interval, which is here 25 000 km or one year..I think 10 000 km is maximum for oil.These engines are in summer really hot, and
because over here many people are driving in high speeds, it may cause the engine is worned out.For myself I have CLS 500 shooting break, which has M278 engine,
so far no problems, but I am trying to find as much informations as possible to prevent engine failure. For another problem-time chaine, check out this page, it will tell you, if you have
new time chaine or old one: (2:40 min in video)...thig guy-he has shop in SAE, he has a lots of videos of M278 or M157 to be repaired...in SAE is really hot, cheap gas and people are driving full throtlle all the time
Sorry for my english, I hope you understand me well

investinwaffles

Actually some guy mentioned in the video that it could be the dual-mass flywheel

That is entirely possible and woudl be fairly easy to hear if you were under the car, with maybe a stethoscope or whatever to isolate the noise to the flywheel area. Only way to know would be to pull the trans sadly but might be worth it if you are embarking on an engine rebuild

cls5504matic

That is interesting. I would also check engine oil again. Like drained and filled to specs. Not siphoned or checked with a dipstick. I found that the dipstick indicates to high or too low depending on the temperature, and I believe a wrong oil level may cause that sound. Just throwing some ideas out there.

To check the cylinder scoring a bore scope through the spark plug is likely useful before a tear down. Interesting discussion re flywheel.

number_one_c55

Hello everyone, yes this was the issue. Heavily scored cylinder walls - requiring engine replacement. We have replaced 3 of these engines since this post. Very unfortunate. Please change your oil everyone, and buyer beware without a scope of the cylinder walls prior to purchase.

TripleC

Dude I as well own a 2013 CLS550 4matic and iam having a ticking sound coming from the central area of the engine below the heat exchanger inter cooler area.

I will be investigating the cylinders with a Bore Scope & determine if the ticking is a cylinder failure or Bottom end issue.

So far there is no Miss Fire or engine light. Power seems to be there under heavy driving.
Very strange that it has a significant ticking sound but doesn't seem to show any symptoms of an engine failure

My engine bay setup!

Mousa

Unfirtunallty it is not a solvable problem . U need to change the engine. I have this problem with my cl500 so all my frwind with this engine. The major problem here a new engine cost more than the market price of the car. A person with this peoblem have to option. O simlpy throug the car the once cost a 300k euro or adapt with that noise . Very unusal and strange for mercedes. Espicially that my car start konockibg on 95k km. For all people asking why im 2 years studinging this. This is purely manfacture defect no matter what u did this will happen sooner or later on these engines . Changing the oil more frequently doesnt help . I changed every 8k to 10k km before starting hearing that noise .

my advice for people like me love to keep cars for a long period even to store not sell. Dont buy these engine u will be disappionted and hate mercedes .

Mousa

Unfortunatly it is not a solvable problem . U need to change the engine. I have this problem with my cl500 and all my frind with this engine have this issue. The major problem in jerusalem. a new engine cost more than the market price of the car. A person with this problem have two options. Or simlpy through the car the once cost a 300k euro or adapt with that noise . Very unusal and strange for mercedes. Espicially that my car start knocking on 95k km. For all people asking why im 2 years studinging this. This is purely manfacture defect no matter what u did this will happen sooner or later on these engines . Changing the oil more frequently doesnt help . I changed every 8k to 10k km before starting hearing that noise .

my advice for people like me who like to keep cars for a long period even to store not sell. Dont buy these engine u will be disappionted and hate mercedes for sure.

Mousa

This is totally correct there is an issue in tgese engine piston all these engine will go bad at some point not far from 200k km. I have this problem at 80k km and mercedes told me i have to change the engine which unfotunalty cost more than the car .