Mercedes M113 V8 Engine Problems, Reliability, Specs

The Mercedes M113 engine family made its debut in 1997. It’s available as a 4.3, 5.0, 5.4, and 5.4L supercharged engine. Power varies from 275 to 574 horsepower – impressive numbers for its era. Some even consider it among Mercedes’ best engines of all time. However, no engine is perfect and there aren’t any exceptions here. In this article, I discuss Mercedes M113 engine problems, reliability, specs, and more.

M113 Engine Variants

Again, the M113 is available in multiple engine sizes depending on the model. All of these V8 engines share the same base design. We’ll discuss specs in the next section, but for now let’s lay out the basics.

4.3L Variant

This is the smallest engine among the M113 family. It has a bore and stroke of 89.9mm x 84mm to achieve its 4.3 liter displacement. Power comes in at 275 horsepower and 295 lb-ft of torque. C43 AMG models receive a bit more power at 302hp and 302 torque. It’s in the following models:

• 1998-2000 C43 AMG
• 1998-2002 E430
• 1998-2003 CLK430
• 1999-2001 ML430
• 1999-2006 S430

5.0 Engine

5.0L variants of the M113 use a 97mm bore and 84mm stroke. To note – it’s the same stroke as the smaller 4.3L engine, so only the bore is increased to achieve its larger size. Power and torque come in at 302hp and 339 lb-ft. It’s found in the following Mercedes-Benz models:

• 1998-2008 G500
• 1999-2006 S500
• 1999-2006 SL500
• 2000-2006 CL500
• 2001-2006 ML500
• 2002-2006 CLK500
• 2003-2006 E500
• 2004-2006 CLS500
• 2006-2007 R500

5.4L Variant

The 5.4 variant is the largest of the M113 engines. It shares the 97mm bore with the smaller 5.0, but stroke increases to 92mm. This engine makes an impressive 342-362hp and 376-391 lb-ft of torque. Very impressive numbers for a naturally aspirated engine of the late 90’s era. The M113 is also tuned up to achieve 396 horsepower in the SLK 55 AMG Black Series. It’s in the following years and models:

• 1998-2000 C55 AMG
• 1998-2001 SL55 AMG
• 1998-2002 E55 AMG
• 2000-2002 S55 AMG
• 2000-2003 ML55 AMG
• 2000-2006 CLK55 AMG
• 2001-2002 CL55 AMG
• 2002-2003 G55 AMG
• 2004-2010 SLK55 AMG
• 2006-2008 SLK55 AMG Black Series
• 2005-2007 C55 AMG

*Many supercharger kits are available to offer similar performance and results to that of the M113K that we’re discussing next.

Supercharged 5.4 M113K

Last but not least is the M113 5.4 Kompressor – also known as the Mercedes M113K engine. It shares the same exact displacement as the previous NA 5.4L engine. A supercharger and twin-intercoolers boost this engine to the next level. Output varies from 469-574 horsepower and 516-590 lb-ft of torque.

• 2003-2006 CL55 AMG
• 2002-2006 S55 AMG
• 2002-2008 SL55 AMG
• 2003-2006 E55 AMG
• 2004-2006 CLK DTM AMG
• 2004-2011 G55 AMG
• 2004-2006 CLS55 AMG

Mercedes M113 Engine Specs

Engine	Mercedes M113
Displacement	4.3L, 5.0L, 5.4L
Configuration	V-8
Aspiration	NA (M113K supercharged)
Bore x Stroke	89.9mm x 84mm (4.3L), 97mm x 84mm (5.0L), 97mm x 92mm (5.4L)
Compression	9.0 : 1 to 11.0 : 1
Valvetrain	3 valves per cylinder (2 intake, 1 exhaust)
Block/Head Material	Aluminum/Aluminum
Horsepower	275-574hp
Torque	295-590 lb-ft

The primary difference between the engines is size, bore x stroke, and compression ratio. However, the M113K supercharged variant does have some other notable differences. We’ll circle back to this point in a moment. Otherwise, the 4.3L, 5.0L, and 5.4L engines share the same base design and architecture. They utilize 3 valves per cylinder with an aluminum block and head.

All engines also receive forged connecting rods, cast camshafts, and a magnesium intake manifold. Some appreciate the M113 engine for its relative simplicity. It was made before the days where VVT was common tech. Despite its simplicity, the engines deliver excellent power and torque for their age.

M113K Differences

We previously mentioned that there are supercharger kits available for the standard 5.4L V8 Mercedes engine. However, the M113K does have quite a few upgrades over the NA 5.4 engine. Most upgrades are intended to help support the added power and boost from the supercharger. The 5.4 Kompressor engine receives a stronger crankcase, crankshaft, pistons, etc.

Mercedes also did some head work to help the engine flow better and increase the redline. Point is – throwing a supercharger on the 5.4L M113 doesn’t necessarily make it the same as the true M113K engine.

3 Common M113 Engine Problems

• Rear main seal
• Intercooler pump
• Spark plugs

Throughout the rest of this article we’ll expand on the above M113 problems in greater depth. However, it’s a good time to add some notes before moving on. We’re considering these among the most common problems. That doesn’t necessarily mean they’re common in the true sense of the definition. Rather, when problems or failures occur these are a few of the common areas.

That said, many consider the M113 engines to be very simple and reliable engines. Age is a big factor, however. Many of these engines are nearing or beyond two decades old. That kind of age can raise some concerns over reliability and longevity.

1) Rear Main Seal Leaks

Up first is a problem that’s very much related to the age and mileage of most 4.3, 5.0, and 5.4L Mercedes V8 engines. Plenty of cars and engines run into oil leaks as they age. Rubber-like seals and gaskets degrade with time and begin cracking. That’s exactly what happens with the M113 rear main seal.

A rear main seal is responsible for sealing the crankshaft where it connects to the transmission. Once cracks develop it begins leaking oil. It usually starts as a small leak that gradually gets worse and worse. As such, M113 rear main seal leaks aren’t usually an urgent problem. However, you’ll still want to replace the rear main seal before the oil leak gets too bad.

It’s an expensive problem thanks to labor. Main seal leaks are also becoming more and more common as these Mercedes M113 V8 engines continue aging. If you’re in the market for one of these cars then check to see if it’s been replaced. Otherwise, it may be a problem you run into in the near future. To note – other oil leaks like valve cover gaskets are also common as these engines age.

Rear Main Seal Symptoms

• Visible oil leak
• Oil loss

Visible leaks on the ground towards the rear of the engine bay are the most likely symptom. It’s often the only symptom you’ll notice. If the leak is bad enough then you might notice the Mercedes V8 is running through oil faster than usual. However, with a leak that bad you should notice it visibly long before.

Other leaks like valve cover gaskets might cause symptoms like light smoke and burning oil smells. A rear main seal often doesn’t result in this since the oil drips to the ground rather than onto hot components.

2) M113K Intercooler Pump Problems

Intercoolers are unique to the supercharged Mercedes M113K. As such, this is an issue that only affects these higher performance engines. The intercooler system is responsible for cooling charge air (pressurized air). Without it, the intake air temps (IAT’s) rise drastically and prompt the computer to shut down the supercharger.

Anyways, the issue at hand is a failure of the M113 intercooler pump. There is an updated Bosch 010 pump that’s a good change if the original IC pump goes bad. Aftermarket options are also a good idea for those running higher boost and power.

Sometimes an IC pump is mistakenly replaced when the entire intercooler system is simply inefficient at higher boost. Running more boost creates more heat, which can quickly overwhelm the stock intercoolers. It’s something to consider if you’re tuning or otherwise modding the Mercedes 5.4 Kompressor.

IC Pump Symptoms

A few symptoms of intercooler pump problems on the Mercedes M113K engine includes:

• Power loss
• Supercharger shutting down
• High IAT’s

The pump failing causes the intercooler system to run at lower capacity or shut down all together. This causes IAT’s to rise, which will lead to worse performance. As temps rise the computer will pull out boost and timing to prevent knocks. Once IAT’s get too hot the computer will completely shut down the supercharger.

Again, these can also be symptoms of an intercooler system that’s simply overwhelmed. If you’re running mods then you may consider some intercooler and other cooling upgrades.

Intercooler Pump Replacement

You can find the updated Bosch 010 part here. At just over $150 it’s a solid option if you’re original M113 Kompressor intercooler pump is going bad. This pump flows a bit better and seems more reliable than the older pumps. Labor is likely a couple hours at a repair shop, so expect a bit of extra cost there. It’s not a challenging DIY for those who know their way around an engine. Here’s a quick video about the IC pump recplacement.

3) Spark Plugs

We’ll speed things up on this section since we don’t consider spark plugs to be a true problem. Spark plugs are simply standard maintenance on most engines including the Mercedes M113. However, it’s worth the mention since the V8 engine uses 2 spark plugs per cylinder. That’s right – this engine uses a whopping 16 spark plugs.

In some ways this highlights some important facts about owning higher performance engines. Even when they’re reliable they can still be more costly to own and maintain. Anyways, spark plugs are a natural wear and tear item but they’re essential to proper operation.

16 spark plugs leaves a lot of room for potential issues. Premature failures aren’t common, but it does happen. Additionally, the supercharged M113K will burn through spark plugs fairly quickly. Boost leads to higher cylinder pressures and puts more stress on ignition components. Don’t overlook something as simple as spark plugs.

Spark Plugs Symptoms

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

As spark plugs wear down they can no longer fully ignite the air/fuel mix in the cylinder. This generally leads to misfires which may show a plethora of other drivability problems on the M113. Power loss is a possible symptom, but it’s often hard to notice on a V8 engine unless multiple cylinders are misfiring. Rough idle and stuttering while accelerating are also common symptoms.

Mercedes M113 Reliability

Is the Mercedes M113 V8 a reliable engine? Yes, we believe this engine earns average to above average regards for reliability. The relative simplicity compared to newer engines helps with reliability some. However, it does have age working against it.

As engines age they naturally require more TLC. Oil leaks, especially the rear main seal, are becoming more common. The supercharged 5.4 M113K is also a bit more demanding on maintenance. Intercooler pumps are one weak spot on the engine, too.

Regardless, the M113 is still a solid and reliable engine all around. Given the age it’s important to look for an example that’s been well maintained. A lot of issues that M113 owners run into are self inflicted. Use quality oils, change fluids on time, and fix problems when they occur. Do all of this and the engine can live a long, reliable life.

M113 Engine Problems Summary

Mercedes first released the M113 engines in 1998 models. They’re available in four different variants: 4.3L, 5.0L, 5.4L NA, and a supercharged 5.4L engine. All engines share the same base design and are capable performers for their era. The 5.4 Kompressor is the most capable, but as a higher performance engine it can be more demanding to own.

Anyways, all variants of the M113 engine offer solid reliability. Oil leaks are becoming commonplace as these engines continue aging. The Mercedes M113 Kompressor is known to have issues with the intercooler pumps. Otherwise, we discussed spark plugs to highlight the fact performance engines can be a bit more demanding on basic maintenance.

Most importantly, look for an example that’s in clean condition with good maintenance. Even though these engines are getting old they can still be pretty reliable when they’ve been taken care of well.

What’s your experience with the Mercedes M113 engine? Drop a comment and let us know!