Reliable V8: Mercedes M176/M177/M178 Engine Problems

Mercedes-Benz V8 engines have been the object of desires of numerous generations of Mercedes fans. The smooth V8 rumble, the incredible power and torque, they’re just something else. Today we’re analyzing another Mercedes V8, and this time it’s the 2015+ M17X series which includes the V8 M176, M177 and M178 engines!

Doing your own research is always a good idea, you just don’t want to get a lemon, especially at this price point where you can find these engines. These cars are very expensive and research is the key in order not to get yourself into a money pit. That’s why we are here to help you out.

First, we are going to learn more about the specs of the M176 engine, then we are going to cover the typical Mercedes engine problems and see what troubles this model has. Once we clear that out of our way, we will cover the applications where you can find these engines. So, let’s get started.

Basic Mercedes M176/M177/M178 Engine Specs

Now let’s first discuss more about the specs of this M176 engine. You will probably come to a few variations when it comes to this engine.

The base version is the M176, then there is the M177, and lastly the most powerful is the M178.

The core of these engines are the same. All three are V8’s and the displacement of this engine is 4.0L. The main difference is the power output that each version makes. Higher horsepower engines have larger turbos to deliver the extra performance, as well as different intakes, exhaust manifolds, and different engine tune.

So, even though these engines are pretty much similar in their design, they are not interchangeable with each other.

Nevertheless, here are the full specs of this engine:

  • Configuration: V8
  • Displacement: 4.0L
  • Cylinder Bore: 83 mm
  • Piston Stroke: 92 mm
  • Block Material: Aluminum
  • Head Material: Aluminum
  • Head Design: DOHC, 4 valves per cylinder
  • Compression Ratio: 10.5:1
  • Turbocharger: Yes
  • Fuel Injection: Direct Injection
  • Redline: 7,000 rpm
  • Horsepower: 456 – 740 hp
  • Torque: 443 – 665 lb-ft (600 – 900 N-m)

Common Mercedes M176/M177/M178 Engine Problems

Common Mercedes M176, M177 and M178 engine problems include:

  • Spark Plug & Coil Failures
  • Carbon Buildup
  • High Fuel Consumption
  • Oil Leaks
  • Doesn’t Particularly Like Mods
  • Expensive Maintenance

Knowing when and how these problems appear is really important in order to be able to tell if the engine has one of these problems. So, let’s dive into the details and learn more about these issues.

Spark Plug & Coil Failures

Spark plugs and ignition coils are not one of the strong sides of this engine. They tend to last quite less compared to other engines.

There are a few reasons behind this concern. But the prime reason is that these engines are using direct injection.

This way of injecting fuel is far more demanding and can easily reduce the lifespan of the ignition components.

The second reason is that these are high-performance engines, especially the M177 and M178. These engines produce serious power.

So, it is understandable that these components will fail more often. The average lifespan is about 40,000 miles (ca. 64,374 km), sometimes even less. It really depends on how hard you push the car and some other factors.

In fact, there was even a recall on this specific issue by Mercedes-Benz by request of the NHTSA. 

Whenever you deal with these types of issues, there will be a check engine light, engine misfires, rough idle, and poor engine work.

Now let’s move on to the next Mercedes M178 engine problems

Carbon Buildup

Carbon buildup is another problem that this engine is troubled with. So, what is carbon buildup, and why does it occur in cars?

Carbon buildup is a buildup of black deposits of carbon on the intake ports. For those who don’t know, the intake ports are the ports where the intake valves are located.

This engine is using something that is known as direct injection. This new way of injecting fuel is done differently compared to older MPI engines.

This direct system uses special injectors for injecting fuel from the top of the cylinder. Rather than the old-school way of injecting fuel through the intake valves.

This has some advantages like improved efficiency and more power. But it also has some downsides. And one of the downsides is carbon deposits.

These deposits occur exactly on the intake ports of the engine. On some high-mileage engines, these carbon deposits can even prevent the valves from opening and closing properly. Which can result in engine misfires and check engine light.

This is why we often recommend that you do a method known as walnut blast every 60,000 miles (ca. 96,561 km) in order to clean off the valves from these deposits and prevent further problems with the engine.

High Fuel Consumption

High fuel consumption was also noted on the M176 engine, this engine is not one of the most fuel-efficient engines around.

This is somewhat normal considering the displacement of the engine. But sometimes this fuel consumption is too high. Far above the EPA numbers.

So, if you want to get a fuel-efficient engine, this is probably not the right engine for you. The new inline-6 turbo that is installed in newer Mercedes models is more efficient than the V8.

Another thing that could be causing this problem is the issue with the ignition coils that we noted previously.

Whenever these coils are not performing as they should, you will have problems with fuel economy. That’s why you need to make sure that the coils are good.

Usually, whenever these components fail, they will start to throw the check engine light and develop misfire codes.

Oil Leaks

Oil leaks are also noted on these engines, not that common, but they can leak oil in some places. Especially the M176 engines that tend to have higher mileage counts compared to the M177 and M178.

The most common places where this engine can leak oil are definitely the valve covers, timing chain cover, and oil pan.

Sometimes they can also blow a main seal, but that does not happen frequently. These are very rare instances. Typically, this happens, when some inexperienced mechanic overfills the engine with oil and this occurs as a consequence of increased engine pressure which eventually destroys the seals. Besides that, there are no serious oil leaks when it comes to this engine.

Doesn’t Particularly Like Mods

Another interesting thing to add when it comes to the M176 engine is that this engine does not like extreme mods.

Many people purchase these engines in order to modify them and pull out some serious power. This is a good way to ruin the excellent reliability of this engine.

When the engine is overloaded, it will show its downsides and weak points. There can be charge pipe failures, it can blow some gaskets and develop more issues. It really depends on how far you push this engine. We don’t recommend pushing it over Stage 1, or better yet, just keep it original and enjoy it!

Expensive Maintenance

The maintenance of this engine is also on the more expensive side. With this engine, you will not get cheap maintenance.

This maintenance will cost you a good penny at the Mercedes dealership. You pay a premium for the car, and you also pay a premium for maintenance costs.

Which Mercedes Have The Mercedes M176/M177/M178 Engine?

M176 Engine

  • 2015 – 2018 Mercedes G500/G550
  • 2017 – 2020 Mercedes S560/S 4MATIC
  • 2017 – 2020 Mercedes Maybach S560/S 560 4MATIC
  • 2017 – 2020 Mercedes S560 Cabrio & Coupe
  • 2018 – Present Mercedes G500/G550
  • 2019 – Present Mercedes GLE 580 4MATIC
  • 2019 – Present Mercedes GLS 580 4MATIC
  • 2021 – Present Mercedes S580 4MATIC
  • 2021 – Present Mercedes Maybach S580 4MATIC
  • 2017 – Present BAIC BJ90

M177 Engine

  • 2015 – 2021 Mercedes C63 & C63 S AMG
  • 2016 – 2022 Mercedes E64 & E63 S
  • 2018 – 2020 Mercedes S63 Coupe & S63 Cabrio
  • 2017 – 2020 Mercedes S63 & S63 S
  • 2018 – Present Mercedes AMG GT 63, GT 63 S, & GT 63 S Performance
  • 2019 – Present Mercedes AMG G63
  • 2018 – Present Mercedes GLC 63 4MATIC
  • 2020 – Present Mercedes GLE 63 & GLE 63 S 4MATIC
  • 2020 – Present Mercedes GLS 63 4MATIC
  • 2020 – Present Mercedes Maybach GLS 600
  • 2022 – Present Mercedes AMG SL 55 4MATIC+ & SL 63 4MATIC+
  • 2022 – Present Mercedes S63 E Performance
  • 2020 – Present Brabus Rocket 900
  • 2017 – Present Aston Martin DB11 & Volante
  • 2018 – Present Aston Martin Vantage V8, Vantage F1, Vantage AMR
  • 2021 – Present Aston Martin DBX V8, DBX707
  • 2023 – Present Aston Martin DB12

M178 Engine

  • 2015 – Present Mercedes AMG GT
  • 2015 – 2020 Mercedes AMG GT S
  • 2017 – Present Mercedes AMG GT C
  • 2017 – Present Mercedes AMG GT R
  • 2020 – Present Mercedes AMG GT Black Series
  • 2022 – Present Mercedes AMG GT Track Series
  • 2023 – Present Aston Martin Valhalla


Mercedes M176/M177/M178 Engine Problems?

This engine does not have many problems. The most serious problem was found on the earlier engines, built from 2015 and 2016 where the ignition coils failed frequently. But besides that, there are no major concerns with this engine, except for some oil leaks and carbon buildup.

I’d even dare to say this engine can go hand in hand with the legendary M113 engine.

Is The Mercedes M176/M177/M178 Engine Reliable?

This engine is fairly reliable. In fact, it is one of the most reliable engines that Mercedes produced and this engine will last for a lifetime if you maintain it properly. This is why we can recommend it to anyone, especially to enthusiasts who want to get the most powerful V8 that Mercedes is producing right now.

A quick Google search through owners’ forums reveal the same opinion from numerous owners.

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