Mercedes OM608 & OM607 Engine Problems (160 CDI, 180d)

If you are in the market for a Mercedes A-Class, B-Class or a Mercedes CLA, you will definitely find this article quite useful since we are going to elaborate on many of the Mercedes OM608 and OM607 engine problems.

These engines were made by Renault in their collaboration with Mercedes-Benz. There was a big pushback against this, since many Mercedes owners could not live with the fact that their new A-Class or the CLA would have the same engine as a Renault or a Dacia.

Nonetheless, doing your own homework before you purchase a car with a certain engine is the way to go. You just don’t want to end up with a car with many issues. And trust us, there are cars that you definitely want to stay away from. This is why we are here to pinpoint these problems for you and hopefully help you out.

First, we are going to cover the basic specs of these two engines, then we are going to elaborate on the Mercedes OM608 and OM607 Benz engine problems and see what trouble these engines have, as well as the models in which you can find them. So, without further ado, let’s dive into the topic.

Basic Mercedes OM608 And OM607 Specs

Before we list the specs of these engines, let’s learn more about the facts. These two engines are not a Mercedes Benz design.

Both the OM607 and OM608 are rebranded Renault K9K dCi engines. They were allegedly co-developed together with Daimler AG. But these engines are just rebranded K9K engines.

This was the case because Mercedes didn’t have the time and resources to develop small engines. So, they simply went to buy already developed engines for their entry-level A-class models.

What is worth noting is that there are two variations of this Mercedes Benz engine, one is the OM607 produced between 2012 and 2018, while from 2018 onward, the newer OM608 was introduced.

OM607 Engine Specs

  • Configuration: inline-4
  • Displacement: 1.5L
  • Cylinder Bore: 76 mm
  • Cylinder Stroke: 80.5 mm
  • Head Design: SOHC, 2 valves per cylinder
  • Compression Ratio: 15.2:1
  • Injection: Common Rail
  • Turbocharger: Yes
  • Power Output: 66 kW (90 hp) to 81 kW (110 hp)
  • Torque Output: 118 to 192 lb-ft (160 – 250 N-m)

OM608 Engine Specs

  • Configuration: inline-4
  • Displacement: 1.5L
  • Cylinder Bore: 76 mm
  • Cylinder Stroke: 80.5 mm
  • Head Design: SOHC, 2 valves per cylinder
  • Compression Ratio: 15.1:1
  • Injection: Common Rail
  • Turbocharger: Yes
  • Power Output: 85 kW (114 hp)
  • Torque Output: 192 lb-ft (260 N-m)

Common Mercedes OM608 And OM607 Engine Problems

Common engine problems with the OM607, OM608 and Renault K9K include:

  • Injectors Tend To Fail
  • Connecting Rod Bearing Failures
  • Poor Oil Pump
  • Glow Plug Failures
  • Turbocharger Failures
  • EGR Valve Failures
  • Clogged DPF

We briefly covered the common Mercedes OM608 and OM607 engine problems, now let’s further elaborate on these problems. Why do we think that this is necessary?

Well, you should be aware of the conditions when they appear, as well as the symptoms they are producing whenever they appear. And also how serious these problems are, so let’s dive into the details.

Injectors Tend To Fail

Fuel injectors are a notorious problem on these engines. Just as on the 1.5 dCi and even on the 1.9 dCi. Mainly because they are similar engines and these problems appear both in Renault, Nissan, and Mercedes models.

So, if you have an OM607 engine in your car or the car that you want to buy, make sure that the injectors are in proper working order. Because if they leak, or if clogged up, you will have a serious problem.

You will most likely have to replace all of them in order to overcome this problem. Or if possible to rebuild them.

And the price for new injectors is pretty high, they can cost up to 300 GBP per piece. So, for four of these injectors, you will pay 1,200 GBP or more than 1,400 EUR to get them all replaced.

There is a variety of injectors used on these engines, Delphi ones are the worst and most sensitive to bad fuel and were replaced once Euro 5 kicked into play with Bosch injectors.

So, if you get a Benz with the OM607, you will highly likely have Bosch injectors. Still, make sure that they are not broken. Since these cost a lot of money as we noted.

Symptoms they often make are the check engine light, trouble starting, poor emissions, and high diesel consumption.

Connecting Rod Bearing Failures

Connecting rod bearing failures were also noted on these engines. The connecting rod bearings tend to fail because of poor maintenance.

These engines are very sensitive maintenance-wise. They are far more sensitive compared to other diesel engines on the market.

So, what a lot of people do is not flush the oil every 6,000 to 8,000 km. They delay the oil change for double or triple the amount of kilometers.

And eventually, the owner will end up with a junk engine. This is why you need to do some preventive maintenance and make sure that you add quality oil and flush this oil often.

In addition to this, it is recommended that you always put in quality fully-synthetic engine oil. These are modern engines and require good-quality engine oil.

Poor Oil Pump Design

This engine is using a chain-driven oil pump. Which hasn’t really been regarded as one of the most innovative things put into cars.

Meaning that it is quite antique and also prone to problems. The pump is also pretty poor in its performance and a lot of people have noted that the rod bearing failure is also attributed to this pump.

The more rarely you flush the oil, the more dirt is collected in the oil pan and this sludge will prevent the pump from operating correctly.

That’s why we recommend having your oil changes regularly, knowing that this pump is not one of the best out there.

Glow Plug Failures

Glow plugs can also fail on these engines. Not often but they can. Some of these engines have already reached 250,000+ km on the odometer and whenever you reach this type of mileage, you just know that you will sooner or later have to replace them.

These glow plugs are not spark plugs. This is a common misconception that happens to people who are not into cars.

But they serve a similar purpose. So, if spark plugs create a spark, glow plugs create heat and help the diesel fuel ignite much quicker at a cold start.

Common symptoms include difficulty starting, check engine light, and poor performance when the engine is cold.

Turbocharger Failures

Turbocharger failures are also quite common on these engines (just like they are on the Mercedes OM628 and OM629 engine). Turbochargers as you probably know are components that deliver boost to the engine, thus creating more power.

The turbocharger has a shaft that rotates and this shaft has many bearings and also seals. Whenever these components reach the end of their lifespan, the shaft will lose balance.

This will result in a whistling sound developing from the turbo. The only way around is to replace or refurbish the turbo. This can be pricey, but you gotta do what you gotta do.

Common symptoms of this issue include whistling noises, check engine light and loss in performance.

EGR Valve Failures

The EGR valve is another common failure point on these diesel engines. The EGR valve is the exhaust recirculation valve and this components are known to fail on Mercedes engines. I noted this issue on the OM611 engine as well.

This valve recirculates some of the gasses and redirects them into the intake. Since it is a valve, it opens and closes.

Over long use, the valve can end up being filled with carbon deposits. These carbon deposits will practically prevent the valve from functioning.

The only way around is to clean the valve or replace it completely. Cleaning it off sometimes does not help since all this debris could have simply failed the valve on the inside. Because the valve has been trying to actuate unsuccessfully for so long.

Clogged DPF

A clogged DPF is also a problem with these engines. The DPF is the diesel particulate filter. This DPF can clog up whenever you drive a lot in the city. Why is this the case?

This is the case because this DPF collects soot and this soot can only be neutralized by the filter whenever it reaches high temperatures.

These temperatures can only be reached at high rpm at highway speeds. So, if you have a diesel engine, you have to regenerate the DPF if you don’t want to end up with a clogged DPF.

Which Models Have The OM608 And OM607 Engines?

Now let’s see which models have these engines.

OM607 Engine

  • 2012 – 2017 Mercedes Benz A-Class
  • 2012 – 2017 Mercedes Benz B-Class
  • 2012 – 2017 Mercedes Benz CLA-Class
  • 2012 – 2017 Mercedes Benz Citan

OM608 Engine

  • 2018 – Present Mercedes Benz A-Class
  • 2018 – Present Mercedes Benz CLA-Class


What Are The Common Problems With OM607 & OM608 Engines?

Common problems with these engines include injector failures, EGR problems, DPF problems, rod bearing failures because of poor maintenance, poor oil pump design, glow plug failures, and turbocharger failures. Basically common diesel issues. In the last couple of years, these engines were much more refined and the newer OM608 does not have many of these common issues.

Are The OM607 & OM608 Reliable?

Yes, these engines are pretty reliable. Except for the early OM607 engine which had some issues with the fuel injectors. Besides that, most of the issues are pretty normal problems that happen on all diesel engines.

If you want to reduce the amount of problems with this diesel engine, check out our guide on how to drive and maintain a diesel powered car to avoid engine problems.

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