Okay, so we’re here, helping you buy your first Mercedes-Benz with a V12 engine. Hope you got some deep pockets, cause this ride ain’t cheap. However, it’s essential that you know what you’re getting yourself into.
Luxury vehicles can be very expensive to fix. Especially Mercedes models that have beefy engines like the M275. This engine is an elephant, it is so large that there is practically no room to work on it, and fixing some issues can be very time-consuming and expensive.
First, we are going to cover the basic specs of this engine. Then, we are going to discuss the Mercedes M275 engine problems, as well as the applications of this engine. So, let’s get started.
Basic Mercedes M275 Engine Specs
The M275 engine is a V12 engine produced by Mercedes-Benz between 2004 and 2014. Many of the modern V12 engines that Mercedes makes are based on this engine design. These include the M158, M285, and M279.
What is worth noting about the M275 engine is that this engine has a V12 layout with six cylinders per bank. The engine is so calm and equally balanced that if you even put a coin on top, the coin will not fall off.
The M275 engine implements an all-aluminum block and aluminum cylinder head. The block is reinforced to guarantee the longevity of the engine.
When it comes to the head design, this engine implements the so-called SOHC layout, which is a single overhead camshaft design with 3 valves per cylinder, as well as two spark plugs per cylinder.
The engine implements a twin-turbo setup. This means that it is boosted and the engine produces different amounts of power depending on the application in which the engine is installed.
For the M275, the numbers are the following:
368 kW (493 hp) to 380 kW (510 hp) @ 5,000 rpm and 800 N-m (590 lb-ft) to 830 N-m (612 lb-ft) of torque @ 1,800 rpm.
As you can tell, numbers vary from application to application. But overall, the numbers this engine makes are in these ranges.
Common Mercedes M275 Engine Problems
Common Mercedes-Benz M275 V12 engine problems include:
- Ignition Coil & Spark Plug Failures
- Turbocharger Failures
- Oil Leaks From Valve Covers
- PCV System Problems
- Air Injection Pump Failure
- Engine Prone To Overheat
Now that we are familiarized with the problems, let’s move on and learn more about them in-depth and see how and when they appear. As well as the symptoms they tend to produce whenever they appear on this engine.
Ignition Coil & Spark Plug Failures
The greatest concern with this engine is the frequent ignition coil and spark plug failures that trouble a lot of owners.
These components are in charge of the ignition system. The ignition coils are small transformers that create high current from the 12v supply. Then they deliver the power to the spark plugs which then create a spark and ignite the fuel.
What is bad about this engine is that there are 24 spark plugs and 12 ignition coils. So, you can see why this is a problem.
The more spark plugs, the higher the chance of developing problems. And they fail at an exponential rate on this engine.
The vast amount of these components also makes them very expensive to be replaced. You can still do this job at home but the cost of the components can be very expensive.
Since in some cases, replacing one or more coils does not help, you will most likely have to replace all of them.
Symptoms of this issue include the check engine light, engine misfires, rough idle, poor fuel economy, engine stalling, and limp mode.
Turbocharger Failures (AMG models)
This makes this engine very tightly packed and the turbos can develop issues like overheating. If they overheat, they start to leak oil.
And that’s what happens with this engine specifically. There are a lot of turbocharger failures reported where the oil starts to leak from the turbos.
The only solution to this problem is to rebuild these turbochargers and the problem will go away. Even so, the rebuilding process can be very expensive.
That’s why before you purchase this engine, we recommend inspecting the turbos and making sure that they do not produce weird noises and also do not leak oil. This way, you will be sure that you avoid any issues in the long run.
Oil Leaks From Valve Covers
Another place where oil leaks can develop is the valve covers. The valve covers are basically two aluminum covers that cover the valvetrain.
These valve covers have a gasket material that is used to seal them together with the cylinder head. And what happens is that this gasket can become old and start to leak oil.
These leaks are nothing too scary. But if not treated on time and if you don’t top off the oil, you risk possible engine damage.
Fortunately, replacing these valve cover gaskets is not something scary and can be done at home. So, if you are into DIY stuff, you will probably enjoy refurbishing the valve covers and replacing the gaskets.
Once the valve cover gaskets are replaced, you will be good to go for many years in the future.
PCV System Problems
Another very common failure point on this engine is the oil separator PCV valve. This valve is located in front of the camshaft of the engine.
And as its name is, it serves the purpose of recirculating the gasses from the crankcase into the intake.
This component can leak oil from its mounting position, which is on the cylinder head itself. Or, the diaphragm inside of this component can completely fail and allow somehow to drench the spark plugs with oil.
This problem can result in serious oil consumption, spark plug fouling, and engine misfires. This issue can make things a lot worse with the spark plug and coil failures.
The solution is to replace the seal rings if they are leaking oil or replace the whole oil separator PCV valve, which is the recommended route.
This component is dirt cheap, costing around $20 new on eBay. Replacing it will do wonders for you as one owner said on a forum.
Air Injection Pump Failure
Problems with the secondary air injection pump on this engine were also noted. If you didn’t know, the secondary air injection pump is a simple air pump.
This pump injects air into the exhaust so the engine can get up to temperature much sooner, reducing pollution in the process.
This pump can fail and cause issues such as the P0410 code. In some cases, it can also cause running issues.
Also, in some situations the problem is not because of the pump, but because of the relay for the pump. So, check this component as well in the process.
Engine Prone To Overheat
This engine can also overheat at some point. Mainly because the cooling system is not quite bulletproof and coolant leaks from the radiator were noted.
So, if you don’t detect these leaks on time, the engine will simply overheat and will blow out the head gasket.
Sometimes the head gasket can also fail by itself and make the engine overheat. So, if the car has a lot of miles, this engine can fail a head gasket at any point since the component is pretty old and much more prone to failure compared to a new head gasket.
Which Models Have The M275 Engine?
Now let’s take a look at which models have the M275 engine.
- 2003 – 2013 Mercedes Benz S600
- 2003 – 2014 Mercedes Benz CL 600
- 2003 – 2011 Mercedes Benz SL 600
What Are The Common Problems With The M275 Engine?
The biggest issues with this engine are caused by the spark plugs and coils. There are 24 spark plugs and 12 ignition coils. A lot of failure points and when they fail, you have to replace them all in some cases. Which can be very expensive.
Other problems associated with the M275 include problems with the PCV valve oil separator, turbocharger failures, oil leaks from the valve covers, head gasket failures, and secondary air injection pump failures were also noted.
Is The Mercedes M275 Engine Reliable?
The Mercedes M275 engine is pretty reliable but not completely bulletproof. The biggest drawback in terms of reliability is the notorious issues with the spark plugs and ignition coils which tend to fail quite frequently. They can trigger engine misfires and the engine will run rather poorly. Uncovering these problems can be expensive and time-consuming.
This is why we cannot give this engine the perfect score. But mechanically, the engine does not have any defect that is a dealbreaker. This engine is a real elephant and definitely one of the best engine designs ever put in production.