Owners with M278 Engines - A Class Action Lawsuit
Thread Starter
Newbie
Joined: May 2025
Posts: 5
Likes: 4
GL550
Owners with M278 Engines - A Class Action Lawsuit
Hey everyone,
I was browsing online today, trying to figure out the oil leak issue with my M278 engine, and I came across something concerning. It turns out there's a class action lawsuit against Mercedes-Benz regarding the M278 engines. The lawsuit alleges that these engines have a manufacturing defect leading to premature engine failure, and that Mercedes-Benz was aware of this but didn't inform customers. The plaintiff claims that after purchasing a CPO GL550, the engine failed due to this defect, and both Mercedes-Benz and the dealership refused to cover the repair costs .
This is particularly alarming because many of us have experienced similar issues—oil leaks, misfires, and even engine failures (e.g. Some owners have reported that the oil leaks originate from the camshaft position sensors, which can lead to oil entering the wiring harness and potentially damaging the ECU, Others have mentioned problems like timing chain wear and cylinder scoring.)
I'm wondering if there's a way we can contribute to addressing this issue or help with that case from the owners' perspectives (and probably also owners from S-class/SL/E forums?). It seems the defendants are trying to dismiss the case early on. If any of you have legal expertise, could you provide some insight into this process?
Let's support each other. Here are the web pages I found.
https://www.pacermonitor.com/public/...USA,_LLC_et_al
https://topclassactions.com/lawsuit-...s-have-defect/
I was browsing online today, trying to figure out the oil leak issue with my M278 engine, and I came across something concerning. It turns out there's a class action lawsuit against Mercedes-Benz regarding the M278 engines. The lawsuit alleges that these engines have a manufacturing defect leading to premature engine failure, and that Mercedes-Benz was aware of this but didn't inform customers. The plaintiff claims that after purchasing a CPO GL550, the engine failed due to this defect, and both Mercedes-Benz and the dealership refused to cover the repair costs .
This is particularly alarming because many of us have experienced similar issues—oil leaks, misfires, and even engine failures (e.g. Some owners have reported that the oil leaks originate from the camshaft position sensors, which can lead to oil entering the wiring harness and potentially damaging the ECU, Others have mentioned problems like timing chain wear and cylinder scoring.)
I'm wondering if there's a way we can contribute to addressing this issue or help with that case from the owners' perspectives (and probably also owners from S-class/SL/E forums?). It seems the defendants are trying to dismiss the case early on. If any of you have legal expertise, could you provide some insight into this process?
Let's support each other. Here are the web pages I found.
https://www.pacermonitor.com/public/...USA,_LLC_et_al
https://topclassactions.com/lawsuit-...s-have-defect/
Newbie
Joined: Jun 2025
Posts: 3
Likes: 0
Catastrophic Engine Failure
2015 GL550 with 99k miles. MB let me know of failure today and need for new engine to the tune of $48k. Any update on lawsuit available and how might we join in? Anyone replace theirs in Austin/San Antonio and have a reputable independent to help me out here?
Super Member
Joined: Feb 2009
Posts: 692
Likes: 73
From: Houston, TX
2003 E55 AMG; 2013 GL550 4Matic; 2003 CL600
There is an extended warranty for the exhaust valve issue, MB replaced an entire head on my motor.
As far as oil leaks, all engines leak oil over time. Repair it when you see the issue. The computer tells you if oil runs low, with plenty of safety margin. I replaced the gaskets on my cam sensors, it was pretty quick.
Newbie
Joined: Jun 2025
Posts: 3
Likes: 0
What did they say failed on it?
There is an extended warranty for the exhaust valve issue, MB replaced an entire head on my motor.
As far as oil leaks, all engines leak oil over time. Repair it when you see the issue. The computer tells you if oil runs low, with plenty of safety margin. I replaced the gaskets on my cam sensors, it was pretty quick.
There is an extended warranty for the exhaust valve issue, MB replaced an entire head on my motor.
As far as oil leaks, all engines leak oil over time. Repair it when you see the issue. The computer tells you if oil runs low, with plenty of safety margin. I replaced the gaskets on my cam sensors, it was pretty quick.
Extended warranty will only allow used engine so took to indie here. They’re tearing down to find point of failure.
No external oil leaks, no smoke, drives fine so nothing on that front.
Did routine oil change then after it, got the low oil light and found it was 2q low after about only 1k miles.
Filled it up again, and got oil light low after only about 300 miles. Took it in and no oil on dipstick.
Very slight, intermittent ticking noise only other symptom beyond warning light. So slight, one would assume normal operation. Super weird.
Newbie
Joined: Jun 2025
Posts: 3
Likes: 0
My indi is $20k but that includes engine, mounts, turbos, etc
Still to see if extended warranty will cover.
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Junior Member
Joined: Oct 2007
Posts: 74
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From: Chicago
2014 S550, 2013 GL450
I honestly did not delve further into what exactly he would do. The quote was a ballpark assuming it was a valve seat issue and not scoring. In any case putting that kind of money into the car at this point is a non-starter for me.
Junior Member
Joined: Oct 2007
Posts: 74
Likes: 16
From: Chicago
2014 S550, 2013 GL450
He did not scope it. He ran a compression test. He is certified Mercedes mechanic that has been servicing my Mercedes for over 10 years. He told me he will do further diagnosis if I want, but he feels it is not worth the time considering the cost of any repair that would be required.
What else may be the cause that would not be an excessively expensive repair?
What else may be the cause that would not be an excessively expensive repair?
MBWorld Fanatic!
Joined: Aug 2003
Posts: 8,882
Likes: 1,212
From: In my garage
E55, GLS450, GL63, GLE350
Just drop in a newer version of the same engine. You can buy complete engines for a fraction of what he is wanting. It will be cheaper to just do the swap and not pay him for labor to maybe determine what is wrong. You DO NOT want to go down that rabbit hole.
MBWorld Fanatic!
Joined: Dec 2006
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
Not a valve seat issue, though it could be that as well. The main issue here is cylinder wall scoring due to faulty Silitec coating. You'd think they would have learned from BMW after the whole Nikasil issue. Make cylinder wall out of STEEL or don't build an engine.
MBWorld Fanatic!
Joined: Aug 2003
Posts: 8,882
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From: In my garage
E55, GLS450, GL63, GLE350
That's not 100% necessary but steel liners would make for a more reliable engine. The Alusil versions seem to be fine but not sure they are durable enough for really high HP turbocharged engine though there are plenty in turbocharged engines. Alusil is typically fantastic for NA engines and last a very long time if not abused. When MB came out with the new coating, I thought to myself that's going to have a high failure rate, it did. When you are a manufacturer and searching for that extra few percent mileage gain for the MPG ratings, you may take unnecessary risks and MB trusted a process that had issues in the long run.
Super Member
Joined: Dec 2007
Posts: 845
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From: ATL
2017 GLS 550
Since the 450 and the 550 from 2013-2014 both have the same V8, just the 450 is detuned. I wonder if you could get a late 2016 - 2019 GL/GLS550 motor which has the cast in iron liners, instead of the Silitec. find a GLS 550 on car-part.com cross reference the VIN on lastvin to look at the engine number if it is later than 2789xx 30 266191 then it should be a viable used engine.
Thread Starter
Newbie
Joined: May 2025
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GL550
Today, when I checked the progress of this lawsuit, I found this
https://www.govinfo.gov/content/pkg/...cv-02770-0.pdf
This file was issued in September 2025.
Some part of the claim got dismissed, while the core complaint will move forward.
https://www.govinfo.gov/content/pkg/...cv-02770-0.pdf
This file was issued in September 2025.
Some part of the claim got dismissed, while the core complaint will move forward.
Member
Joined: Oct 2009
Posts: 214
Likes: 38
From: East Idaho
2014 GL450, 2006 S500, 2003 ML350, 1996 C280 (Prev 1995 C220, 2002 CLK320, 1980 300SD Turbo)
Today, when I checked the progress of this lawsuit, I found this
https://www.govinfo.gov/content/pkg/...cv-02770-0.pdf
This file was issued in September 2025.
Some part of the claim got dismissed, while the core complaint will move forward.
https://www.govinfo.gov/content/pkg/...cv-02770-0.pdf
This file was issued in September 2025.
Some part of the claim got dismissed, while the core complaint will move forward.
Newbie
Joined: Sep 2025
Posts: 7
Likes: 1
From: Northern Virginia
Ml320, ml550
Cylinder scoring from defective cylinder lining is another defect
Hey everyone,
I was browsing online today, trying to figure out the oil leak issue with my M278 engine, and I came across something concerning. It turns out there's a class action lawsuit against Mercedes-Benz regarding the M278 engines. The lawsuit alleges that these engines have a manufacturing defect leading to premature engine failure, and that Mercedes-Benz was aware of this but didn't inform customers. The plaintiff claims that after purchasing a CPO GL550, the engine failed due to this defect, and both Mercedes-Benz and the dealership refused to cover the repair costs .
This is particularly alarming because many of us have experienced similar issues—oil leaks, misfires, and even engine failures (e.g. Some owners have reported that the oil leaks originate from the camshaft position sensors, which can lead to oil entering the wiring harness and potentially damaging the ECU, Others have mentioned problems like timing chain wear and cylinder scoring.)
I'm wondering if there's a way we can contribute to addressing this issue or help with that case from the owners' perspectives (and probably also owners from S-class/SL/E forums?). It seems the defendants are trying to dismiss the case early on. If any of you have legal expertise, could you provide some insight into this process?
Let's support each other. Here are the web pages I found.
https://www.pacermonitor.com/public/...USA,_LLC_et_al
https://topclassactions.com/lawsuit-...s-have-defect/
I was browsing online today, trying to figure out the oil leak issue with my M278 engine, and I came across something concerning. It turns out there's a class action lawsuit against Mercedes-Benz regarding the M278 engines. The lawsuit alleges that these engines have a manufacturing defect leading to premature engine failure, and that Mercedes-Benz was aware of this but didn't inform customers. The plaintiff claims that after purchasing a CPO GL550, the engine failed due to this defect, and both Mercedes-Benz and the dealership refused to cover the repair costs .
This is particularly alarming because many of us have experienced similar issues—oil leaks, misfires, and even engine failures (e.g. Some owners have reported that the oil leaks originate from the camshaft position sensors, which can lead to oil entering the wiring harness and potentially damaging the ECU, Others have mentioned problems like timing chain wear and cylinder scoring.)
I'm wondering if there's a way we can contribute to addressing this issue or help with that case from the owners' perspectives (and probably also owners from S-class/SL/E forums?). It seems the defendants are trying to dismiss the case early on. If any of you have legal expertise, could you provide some insight into this process?
Let's support each other. Here are the web pages I found.
https://www.pacermonitor.com/public/...USA,_LLC_et_al
https://topclassactions.com/lawsuit-...s-have-defect/
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