M278 vs. M176 Comparison
Thread Starter
Junior Member
Joined: Jun 2024
Posts: 63
Likes: 35
2013 S63 AMG, 2015 S550
M278 vs. M176 Comparison
Hello, I've read some of the reviews here. Seems to be mixed. For anyone that's had both pre- and post-facelift, is there any reason to upgrade to the newer engine based on engine alone? I imagine the smaller displacement having less torque. What would be its advantages?
Senior Member
Joined: Mar 2010
Posts: 477
Likes: 124
2016 S550
Better efficiency/fuel economy (cylinder deactivation), although it’s been reported that the engine has more noticeable vibrations at idle.
More power on paper, but like you said, less lower end torque, so probably doesn’t feel stronger.
Hot V turbo configuration allows for easier access to turbos.
No cylinder boring issues as far as we know.
More power on paper, but like you said, less lower end torque, so probably doesn’t feel stronger.
Hot V turbo configuration allows for easier access to turbos.
No cylinder boring issues as far as we know.
Out Of Control!!
Joined: Sep 2018
Posts: 14,666
Likes: 4,568
From: unbegrenzt
2017 GLE350 4MATIC
^agree^
Oil vapor separator failure which can lead to rear main seal failure is not uncommon on C63 and E63, and other models to a seemingly lesser extent. Appears to be vehicle-installation-dependent.
Oil vapor separator failure which can lead to rear main seal failure is not uncommon on C63 and E63, and other models to a seemingly lesser extent. Appears to be vehicle-installation-dependent.
MBWorld Fanatic!
Joined: Nov 2014
Posts: 4,242
Likes: 628
From: Chicago burbs
2015 S550
MBWorld Fanatic!
Joined: Aug 2007
Posts: 1,823
Likes: 792
From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
Pretty much every engine from every mfr that has cylinder deactivation has vibration issues and the engines end up with oil consumption issues and spark plugs that need to be replaced more often. Even though the cylinders stop firing, fuel is still entering the combustion chamber. Even Honda has issues with this in their engines.
And to the point about vibration; it's real but not a problem. When all 8 cylinders are activated the engine has more balanced power, meaning a combustion event for every 45 degrees of crank shaft rotation. When you deactivate 4 cylinders you have combustion at every 90 degrees of crankshaft rotation. It is what it is, but it isn't a problem. It's just a normal feature of a 4 cylinder combustion cycle. Old school cylinder deactivation from the 1980's was a total disaster, this isn't the same.
MBWorld Fanatic!
Joined: Dec 2011
Posts: 4,372
Likes: 945
W212 FL
M176s look like don't have the issues that M278s have had in the past but I don't know I still love M278s . Even 2.0 liter C63 E Performance engine could blow M278's performance out of water but V8 is a different world to me
Super Member
Joined: Jan 2009
Posts: 566
Likes: 261
From: In The Woods
2019 W222 S560 4Matic/2025 Yukon Denali
I tuned my 4.0.....no more cyl deactivation.....Did the same thing to the wife's Chevy....on her truck you could really feel it, the judder.....
Need all 8, thats what I bought a V8 for.
Need all 8, thats what I bought a V8 for.
Trending Topics
MBWorld Fanatic!
Joined: Jun 2015
Posts: 9,062
Likes: 4,565
From: Maryland
2024 S580
The thing I would look out for with the M176 is the failed valve cover gaskets mine had. This is usually found when the spark plugs are replaced and its a HUGE job to do this ($8-9K at the dealer, $5k at an independent), my car was impacted and I think I was the first and there have been a few more. More common on the AMG variant but it can happen to the 560 also.
I have been told that 5k vs 10k OCIs can prevent this issue, in my S580 with the M176 I am doing 5K OCIs.
I have been told that 5k vs 10k OCIs can prevent this issue, in my S580 with the M176 I am doing 5K OCIs.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
MBWorld Fanatic!
Joined: Aug 2007
Posts: 1,823
Likes: 792
From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
The thing I would look out for with the M176 is the failed valve cover gaskets mine had. This is usually found when the spark plugs are replaced and its a HUGE job to do this ($8-9K at the dealer, $5k at an independent), my car was impacted and I think I was the first and there have been a few more. More common on the AMG variant but it can happen to the 560 also.
I have been told that 5k vs 10k OCIs can prevent this issue, in my S580 with the M176 I am doing 5K OCIs.
I have been told that 5k vs 10k OCIs can prevent this issue, in my S580 with the M176 I am doing 5K OCIs.
MBWorld Fanatic!
Joined: Jun 2015
Posts: 9,062
Likes: 4,565
From: Maryland
2024 S580
The 10k MB specifies. According to my independent Benz mechanic the issue is caused by clogged oil separators creating additional pressure in the crankcase, the separators get clogged because of the longer OCI. If you think about it that makes sense.
Super Member
Joined: Jan 2009
Posts: 566
Likes: 261
From: In The Woods
2019 W222 S560 4Matic/2025 Yukon Denali
I do 5k oil changes.
like religion.
i change out trans/diffs/trans case every 50k
spark plugs every 50k
brake fluid flush every 2-3 years
if you do that, the car will run past 200k.
when i got rid of my s430 it had 187k on it and it still dis what it was supposed to do when i hit the pedal.
Machines love fresh fluids…
my car has the 4.0tt and about 100k miles on it.
mostly highway miles.
like religion.
i change out trans/diffs/trans case every 50k
spark plugs every 50k
brake fluid flush every 2-3 years
if you do that, the car will run past 200k.
when i got rid of my s430 it had 187k on it and it still dis what it was supposed to do when i hit the pedal.
Machines love fresh fluids…
my car has the 4.0tt and about 100k miles on it.
mostly highway miles.
Last edited by vinflouen; Dec 23, 2024 at 06:57 PM.
MBWorld Fanatic!
Joined: Aug 2007
Posts: 1,823
Likes: 792
From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
The longest OCI I've ever done was 7500 miles, but that's just me. I've averaged around 5K wilth my S-class cars. Thanks for the datapoint on what NOT to do.
MBWorld Fanatic!
Joined: Sep 2019
Posts: 3,112
Likes: 1,490
From: U.S.
Current/Last 5-years:GLS;G70;Alpina B8;X7;Accord. Sold:X7,TeslaS;S560;S550,X5;530e;L.Navigator;LS460
Pretty much every engine from every mfr that has cylinder deactivation has vibration issues and the engines end up with oil consumption issues and spark plugs that need to be replaced more often. Even though the cylinders stop firing, fuel is still entering the combustion chamber. Even Honda has issues with this in their engines.
The electric boost in the 48V in the W223 solved all of that….
Super Member
Joined: Nov 2016
Posts: 602
Likes: 273
From: NYC
S63, GLE580, BV250
not m278 or m176*
I sent out a few samples of oil for lab work from my m157. The oil at 5,000mi, viscosity and everything was still up to spec. Another sample I pushed off to 7,500mi was still up to spec but there was a noted decrease in viscosity.
With that said, I wouldn’t change earlier than 5k wouldn’t change later than 7.5k, gives me plenty of in between time to review upcoming service then schedule accordingly with my Indy.
I sent out a few samples of oil for lab work from my m157. The oil at 5,000mi, viscosity and everything was still up to spec. Another sample I pushed off to 7,500mi was still up to spec but there was a noted decrease in viscosity.
With that said, I wouldn’t change earlier than 5k wouldn’t change later than 7.5k, gives me plenty of in between time to review upcoming service then schedule accordingly with my Indy.
MBWorld Fanatic!
Joined: Aug 2017
Posts: 1,695
Likes: 521
2019 S560, 2015 Honda Civic Hybrid
Peering under the hood of my new-to-me S560 and the M176 engine and don't see a belt drive in front of the engine ... is that correct? Wondering how exactly they charge the battery or compress refrigerant without a belt-driven alternator or compressor?
Isn't A/C season right now but I'd be delighted to find out I have a battery-powered compressor that keeps running when the engine's in auto-stop!
Isn't A/C season right now but I'd be delighted to find out I have a battery-powered compressor that keeps running when the engine's in auto-stop!
Out Of Control!!
Joined: Sep 2018
Posts: 14,666
Likes: 4,568
From: unbegrenzt
2017 GLE350 4MATIC
I don't see this come up on W223, V/X167, W213 AMG or W205 AMG sections of the site. The 4.0TTV8 is just now reaching the age where leaking cam magnets and cam sensors would start to show themselves.
Thread Starter
Junior Member
Joined: Jun 2024
Posts: 63
Likes: 35
2013 S63 AMG, 2015 S550
Do you guys feel the M278 gets a bad rep due to poor maintenance and owners perhaps not being conscientious with their driving habits? I personally don’t see the 4.0 as an upgrade. You get lower displacement and cylinder deactivation which has to be programmed out if you dont want it. However, I do like the facelift and the ICE updates.
Out Of Control!!
Joined: Sep 2018
Posts: 14,666
Likes: 4,568
From: unbegrenzt
2017 GLE350 4MATIC
Do you guys feel the M278 gets a bad rep due to poor maintenance and owners perhaps not being conscientious with their driving habits? I personally don’t see the 4.0 as an upgrade. You get lower displacement and cylinder deactivation which has to be programmed out if you dont want it. However, I do like the facelift and the ICE updates.
The biggest known defect of the M17x 4.0TTV8 hot vee is failed oil vapor separators which cause collateral damage of failed rear main crankshaft oil seal. And early M17x had unsolved misfire issues which some have reported were solved with new coils, plugs and ECU programming at the dealer. The M17x and M278 are not long term reliable engines the way the M276 is.
MBWorld Fanatic!
Joined: Jun 2015
Posts: 9,062
Likes: 4,565
From: Maryland
2024 S580
Do you guys feel the M278 gets a bad rep due to poor maintenance and owners perhaps not being conscientious with their driving habits? I personally don’t see the 4.0 as an upgrade. You get lower displacement and cylinder deactivation which has to be programmed out if you dont want it. However, I do like the facelift and the ICE updates.
Unanswerable question on the M278. Alleged iron liners are questionable when looking at examples on this site which appear to have iron liners and which are earlier than the alleged iron liner changeover point. So the story is unclear. Bore scoring on M278 is a clear reality.
The biggest known defect of the M17x 4.0TTV8 hot vee is failed oil vapor separators which cause collateral damage of failed rear main crankshaft oil seal. And early M17x had unsolved misfire issues which some have reported were solved with new coils, plugs and ECU programming at the dealer. The M17x and M278 are not long term reliable engines the way the M276 is.
The biggest known defect of the M17x 4.0TTV8 hot vee is failed oil vapor separators which cause collateral damage of failed rear main crankshaft oil seal. And early M17x had unsolved misfire issues which some have reported were solved with new coils, plugs and ECU programming at the dealer. The M17x and M278 are not long term reliable engines the way the M276 is.
Out Of Control!!
Joined: Sep 2018
Posts: 14,666
Likes: 4,568
From: unbegrenzt
2017 GLE350 4MATIC
It has some very clear reliability concerns with age, as with anything else you need to stay on top of them. Don't get an early one to make sure you get the iron liners. Personally I would want the refresh for many reasons the M176 is just one of them.
I've never seen anybody but you talk about the failed rear crankshaft oil seal caused by the oil separators, that can cause the failed valve cover gasket I had. I have been told shorter OCIs will help that.
I've never seen anybody but you talk about the failed rear crankshaft oil seal caused by the oil separators, that can cause the failed valve cover gasket I had. I have been told shorter OCIs will help that.
MBWorld Fanatic!
Joined: Jun 2015
Posts: 9,062
Likes: 4,565
From: Maryland
2024 S580
Yep, I do...but not the AMG variant forums only forums for models that interest me. Just because something is an issue in the M178 doesn't mean that is necessarily an issue with the M176. We know the valve cover gasket failure is a potential issue with the M176 because we have seen that, I can't recall any rear main seal failures in an M176.
My advice (and what I am doing with the M176 in my S580) is change the oil every 5k to avoid oil separator clogging.
My advice (and what I am doing with the M176 in my S580) is change the oil every 5k to avoid oil separator clogging.
MBWorld Fanatic!
Joined: Jun 2015
Posts: 9,062
Likes: 4,565
From: Maryland
2024 S580
Why don't you share your "data" with us? Instead of just lobbing grenades and scaring everybody actually provide us something of value. Please share with us the rear main seal failures on the M176 specifically that would substantiate that being a primary concern for buyers....
Last edited by SW20S; Dec 26, 2024 at 12:19 PM.
Out Of Control!!
Joined: Sep 2018
Posts: 14,666
Likes: 4,568
From: unbegrenzt
2017 GLE350 4MATIC
Why don't you share your "data" with us? Instead of just lobbing grenades and scaring everybody actually provide us something of value. Please share with us the rear main seal failures on the M176 specifically that would substantiate that being a primary concern for buyers....
