Mercedes M276 Engine Problems: The 4 Most Common Issues

Mercedes M276 Engine Problems

Mercedes-new Benz’s M276 engine replaces the M272 that came before it. The Fiat-Chrysler 3.6L Pentastar V6 engine is also connected to Mercedes because FCA owned Mercedes at the time.. Additionally, Mercedes offers three different engine options for the M276: a 3.5L naturally aspirated (NA), 3.0L twin turbo, and 3.5L twin turbo.

They’re all excellent choices because they strike a good balance between power and cost-effectiveness. Despite this, no engine is faultless, and this isn’t an exception. The Mercedes-Benz M276 V6 engine and overall reliability are discussed in this article.

Mercedes M276 Engine Variants

It’s critical to understand the differences between the M276 engines before continuing. The M276 family of engines is discussed in this article. Some of the issues we discuss, on the other hand, may have a greater impact on some variants than others.

Where necessary, we’ll provide clarification in the text. Allow me to lay out all the engine types and then provide a list of automobiles using each one.

Mercedes M276 DE 35 3.5L NA

The original M276 DE 35 engines have a 3.5-liter capacity and a 60-degree V6 layout. However, they use direct injection and a high-pressure fuel system in addition to being naturally aspirated. Mercedes V6 engines now have cutting-edge new technology to help with fuel economy, emissions, and performance.

NA engines such as the M276 DE 35 have respectable power outputs ranging from 248 to 302 horsepower. Mercedes-Benz makes the following models with this feature:

  • 2011-2014 W218 CLS350
  • 2011-2016 W212 E300
  • 2012-2016 W212 E350
  • 2012-2016 W212 E400 Hybrid
  • 2011-2014 W204 C300
  • 2011-2014 W204 C350
  • 2012-2015 W166 ML350
  • 2012-2015 X204 GLK350
  • 2010-2013 W221 S350
  • 2013-2017 W222 S400 Hybrid
  • 2011-2015 R172 SLK350

M276 DE 30 LA Twin Turbo 3.0L

Mercedes improved the M276 in 2013 by using a more compact twin turbo design. Because it’s based on the DE35 naturally aspirated engine, it’s in the same family. Compression, on the other hand, is reduced from 12.2 psi to 10.7 psi to accommodate the turbocharger’s increased pressure. Two IHI turbos help the M276 DE 30 generate 328 hp and 354 lb-ft of torque with quick spool and minimal turbo lag.

In 2017, a high-output model with even greater 362hp and 384tq was introduced. In 2019, the latest M276 DE30 engines will be able to produce 385hp and 384tq thanks to a third update. Mercedes-Benz offers the DE 30 LA in a number of different configurations.

  • 2013-2016 W212 E400
  • 2016-2018 W213 E400
  • 2019-2020 W213 E450
  • 2014-2017 W218 CLS400
  • 2015-present W205 C400
  • 2015-2017 W205 C450
  • 2014-2017 S500 Plug-in Hybrid
  • 2018-2020 W2200 S560 e
  • 2014-2019 X166 GL450 / GLS450
  • 2015-2017 W166 ML400
  • 2016-2018 W166 GLE 450 / GL 550 e
  • 2015-2019 W166 GLE 43 AMG
  • 2015-present X253 GLC 43 AMG
  • 2016-present W205 C 43 AMG
  • 2016-2018 W213 E 43 AMG

DE 35 LA Twin Turbo 3.5L V6

In terms of displacement, bore x stroke, etc., M276 DE 35 LA engines are very similar to the original NA variant. The addition of twin turbochargers is, of course, the most significant difference.

With 328hp and 354tq, the Mercedes 3.0 twin turbo V6 is the benchmark against which this engine will be measured. The increased displacement serves the purpose of utilizing less turbo boost. Its larger size actually improves efficiency. These automobiles all use DE35LA engines:

  • 2013-2017 W222 S400
  • 2015-2017 W222 Maybach S400

4 Common M276 Engine Problems

Mercedes M276 Engine

Mercedes M276 V6 engine issues include the following:

The following sections of the article will go into greater detail on the topics mentioned above. In any case, now would be a good time to make a few quick observations. All of the M276 engines have a good track record of reliability. There’s a good reason why these are the most common issues.

However, this does not rule out the possibility that these are not isolated incidents affecting a significant number of Mercedes M276 engines. Instead, these are some of the most common places where issues arise.

The M276 is available in a number of configurations, including the DE35 NA, DE30 twin turbo, and DE35LA twin turbo, as previously discussed. We’ll figure out if a problem only affects some M276 engines and none of the rest.

Another factor to think about is the fact that twin turbo engines provide more performance and tuning flexibility. Turbo M276 engines, on the other hand, are more expensive to maintain than NA DE35 engines.

We could make a reference to the various M276 engine configurations (i.e M276 DE 30). In general, it applies to all M276 engines, unless otherwise stated.

1) Mercedes-Benz M276 HPFP Issues

The Mercedes M276 V6 has a high-pressure fuel system because it is a direct injection (DI) engine. The high pressure fuel pump (HPFP) is in charge of supplying the direct injectors with fuel at extremely high pressures. Failures in HPFP aren’t unheard of. The N54, BMW’s first mass-produced turbo DI engine, was plagued by problems. Early on, VW had a slew of issues.

It’s safe to say that HPFP failures on the Mercedes M276 are a lot rarer. On the other hand, Mercedes M276 engine HPFP issues can and do arise. As some early engines continue to age, it appears that more and more cases will arise. Anyway, while this failure isn’t common, it should be noted nonetheless.

A wide range of signs indicate a malfunctioning Mercedes V6 high pressure fuel pump. Fortunately, failures of the M276 HPFP usually occur over a period of months or even years rather than all at once. However, most HPFP failures are likely to occur north of 80,000 miles, with some encountering problems as early as 30,000 miles into the trip.

Symptoms of M276 HPFP Failure

In the event your Mercedes M276 V6 HPFP exhibits any of the following symptoms, it may be having issues:

An unusually long crank, especially on cold starts, is one of the first signs of HPFP failure. Of course, the M276 engine can suffer from long cranks due to a variety of other problems, so be sure to check the basics first. You’ll have more drivability issues if you don’t fix the HPFP issues.

As the HPFP deteriorates, common symptoms include stuttering, hesitation, rough idle, and power loss. You should also see a check engine light and error codes indicating that the fuel pump is not delivering the intended flow and pressure.

MB M276 V6 HPFP Replacement

When compared to the struggles of other DI systems, HPFP aren’t as common on the M276. Another plus is the M276 fuel pump’s low price of $300-600. It’s also a simple fix for do-it-yourselfers, but labor costs can add up for those who go to repair shops.

2) M276 Carbon Build-Up Problems

M276 Carbon Build-Up Problems

Another interesting aspect of direct injection is carbon buildup. Natural oil blow-by is produced by all engines and gets into the intake ports. Fuel is sprayed into the intake ports with traditional port injection (PI). This aids in removing any oil deposits from the intake ports and valves that may have accumulated. The disadvantage of direct injection (DI) is that it sprays fuel directly into the cylinder, leaving no way to remove any deposits.

In the preceding section, we discussed the N54 engine and Volkswagen/Audi. Excess carbon built up in the same engines as soon as 40,000 to 60,000 miles.

When it came to the M276 V6 engine, Mercedes excelled. Some people assert that carbon buildup isn’t even an issue. When used in conjunction with the PCV system, the separator helps to keep carbon buildup to a minimum. However, carbon builds up in the intake ports even when nothing is sprayed over them.

It’s still unclear exactly when this will cause problems. As more and more M276s reach 100,000 miles in mileage, carbon buildup is likely to become an issue. It’s not a big deal, and some M276 engines will likely be fine without carbon cleaning for the rest of their working lives. Excessive deposits, on the other hand, can impair performance and drivability.

The twin turbo DE35LA and DE30 are more likely than the NA DE35 M276 to accumulate carbon. Boost-induced cylinder pressure increases increase the likelihood of blow-by.

Mercedes V6 Carbon Build-Up Symptoms

Here are a few signs of a carbon overload:

  • Rough idle
  • Stuttering/hesitation
  • Misfires
  • Power loss

Carburetor intake valves and ports become more and more restricted as carbon deposits build up. This results in a loss of power, but because it happens gradually over time, it is usually difficult to notice. As carbon deposits continue to worsen, you may experience misfires, stuttering, and a rough idle in your vehicle.

M276 Carbon Build-Up “Fix”

We’re used to dealing with carbon build-up and cleaning methods from our time on the BMW N54. Walnut blasting of the intake ports is a tried and true method.

The walnut media shells and a heavy-duty shop vac are needed for this project. To get to the ports and valves, you’ll need to remove the M276 intake manifold. Once you’re inside, the walnut blasting process takes about an hour or so.

Cleaning the M276 intake valves can cost anywhere from $400 to $600 at a shop. Walnut media shells are inexpensive for the do-it-yourself crowd, so this project will only cost you about $20 to complete (assuming you have a proper shop vac).

3) MBZ M276 Timing Chain Tensioners

When starting up, some M276 engines rattle. As a result, Mercedes issued a service bulletin to address the issue. The main problem is with the tensioner and check valves for the timing chain. Fortunately, Mercedes had some newer parts by 2014, which fixed the problem. Since this is the case, timing chain tensioner issues are most prevalent in NA DE35 M276 engines that were built before 1975.

Whatever the case may be, the M276 secondary chain tensioners fail to receive enough oil flow when the engine is first started. Until the oil pressure is high enough, the engine will rattle and make rattling noises. Repairing the timing chain is easier with the help of the new tensioner and check valves.

Other problems can, of course, cause rattling during startup and exacerbate existing timing chain issues. On newer models, this is less of an issue, but older M276 engines may have it. This video may be of assistance to those who hear rattling when their computer first starts up.

M276 V6 Timing Chain Tensioner Symptoms

The following are symptoms of a Mercedes M276 engine timing chain tensioner problem:

  • Rattling
  • Fault codes
  • CEL
  • Poor operation

With the tensioners lacking oil flow at startup, the most common symptom is rattling. Fault codes, a check engine light, and poor engine performance can all be caused by a faulty timing chain tensioner or other timing chain components.

Timing Chain Tensioner Replacement

Just the parts for the new tensioners and check valves are reasonably priced. On top of that, labor costs can be substantial. There was a service bulletin for this problem, and many people’s cars were still under warranty because of it. For problems that occur after the warranty has expired, Mercedes may be willing to assist you in paying for repairs.

4) Mercedes M276 Ignition System Problems

Alright. This isn’t even something we consider to be a problem. The M276’s spark plugs and ignition coils are routinely serviced, as is the case with many other engines. Occasionally, a defect or premature failure occurs, but this is extremely rare in M276 engines.

This section was added primarily to compare and contrast the naturally aspirated (NA) and turbocharged (T) M276 V6 engines. Spark plugs and ignition coils wear out much faster in turbo engines than in naturally aspirated ones.

Turbo cars use more plugs and coils because of the increased cylinder pressures, additional air and fuel, and so on. The lifespan of a NA engine is likely to be halved. This is particularly valid when working with the M276 DE30 or DE35LA twin turbocharged motors.

In any case, the M276 engine’s plugs and coils aren’t a major issue. Turbo engines can be more difficult to maintain, as this example shows. Turbo engines have numerous disadvantages, such as the fact that they have more moving parts that could break.

Our favorite turbo engines are the Mercedes 3.0L and 3.5L twin turbo units, so those are our top picks. For those who aren’t familiar with turbo engines, it’s just something to keep in mind.

M276 3.0 & 3.5 Plugs & Coils Symptoms

It may be necessary to replace the Mercedes M276 spark plugs or coils if you notice the following symptoms:

  • Misfires
  • Rough idle
  • Power loss

A few misfires here and there are signs that your spark plugs and ignition coils need to be replaced. Replace them as soon as possible because if you don’t, they’ll keep getting worse, resulting in issues like rough idle or even power loss.

Mercedes V6 Plugs & Coils Replacement

Most engines, including the Mercedes V6 M276 have easy-to-replace ignition coils and spark plugs. Even the most inexperienced do-it-yourselfers can complete the project with relative ease. Spark plugs cost between $60 and $100, while ignition coils cost between $200 and $300.

The spark plugs and ignition coils should last about 70,000 miles on the M276 DE35. The turbo M276 DE30 and DE35LA require new plugs every 50,000 miles or so, whereas coils last about twice as long on those models with the smaller turbochargers.

M276 Engine Reliability

M276 Engine Reliability

Is the Mercedes M276 V6 engine dependable? For reliability, we’ll use the M276 average, which rewards comments that are better than average.

Performance, efficiency, and dependability are excellent in all configurations, including the twin turbocharged models. There aren’t many common problems or design flaws with the M276. Unlike some other manufacturers, Mercedes was able to avoid widespread DI issues.

However, as previously mentioned, twin turbo engines come at an additional cost in terms of upkeep and operation. The DE30 and DE35LA versions of the M276 are still fantastic engines in every way.

Boost, on the other hand, is hard on components that are prone to wear and tear, such as spark plugs and ignition coils. Even though there are more moving parts, the M276 doesn’t seem to have any common turbo problems.

Some of the adequacy is simply a matter of chance. Maintenance, on the other hand, is something we can manage. Make sure to use high-quality oils, to replace fluids on a regular basis, and to address problems as they arise. Mercedes-Benz M276 owners should take care of their engine if they want a fun and reliable ride.

Mercedes M276 Common Problems Summary

The M276 engine family from Mercedes-Benz has a lot to offer. There are three different V6 engines available: a 3.5L naturally aspirated, a 3.0L twin turbo, and a 3.5L twin turbo. They’re all great engines, with a nice mix of power, dependability, and efficiency all in one package. But no engine is perfect, and the M276 is no exception.

Direct injection is an amazing piece of equipment, but it has some drawbacks. As the M276 gets older, HPFP failures are becoming more common. However, these issues are still extremely rare.

For the time being, carbon buildup isn’t a problem, but walnut blasting will likely be necessary around the 100,000-mile mark as preventative maintenance. Some early M276 engines had a problem with the timing chain tensioners being dry, which caused rattling when the engine was started.

Otherwise, we talked about spark plugs and ignition coils to show that turbo engines can be a little more difficult to keep in top working order.. There are no reports of any major problems with the Mercedes M276 twin turbo engines so far. If you take good care of your M276 engine, you’ll have a long, happy life with it.

Your experience with Mercedes’ M276 V6 engine would be greatly appreciated. Are you thinking about getting one?

If you have anything to add, please do so in the comments below.

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