Buying a used car can be a daunting task, especially if it’s a Mercedes-Benz with the OM611 engine. We’ve talked about the big brother of the OM611 engine, the OM612 before, and we even talked about the engine that came after the OM611 engine, the OM646 diesel engine.
But today we’re talking about the OM611 engine and all of its common problems. Keep in mind that these are now old engines and if you buy an example that was poorly maintained, you can experience many more problems than just the ones listed here today.
You definitely need to learn more about the Mercedes OM611 engine problems before you make a purchase. Since fixing these engines can be very expensive if you are not aware of these issues.
This article will be all about uncovering the common problems of this OM611 engine, as well as the specs and the applications in which you can find the OM611. In the end, we are going to answer some frequently asked questions. So, without further ado, let’s dive into the topic.
Basic Mercedes OM611 Engine Specs
If you are into diesel engines, you are probably familiarized with the specs of the OM611 engine. If not, let’s cover them real quick.
The OM611 engine is an inline-4 engine that was introduced by Mercedes Benz in 1998. This engine features forced induction and we can honestly say that this was the first proper modern diesel that Mercedes introduced to the market.
This engine features modern technologies such as EGR, common-rail injection, and turbocharging. These were big novelties back then and helped this engine to create decent power for its size.
Now let’s share some of the specs of the OM611 engine:
- Configuration: inline-4
- Displacement: 2.1L and 2.2L
- Block Material: Cast Iron
- Head Material: Aluminum
- Cylinder Bore: 88 mm
- Piston Stroke: 88.4 / 88.3 mm
- Timing Drive: Chain Driven
- Cylinder Head Design: DOHC 4 valves per cylinder
- Turbocharger: Yes, variable geometry turbo
- Fuel System: common rail direct injection
- Power Output: 80 – 141 hp (60 – 105 kW)
- Torque Output: 148 – 232 lb-ft (200 – 315 N-m)
Common Mercedes OM611 Engine Problems
Common problems with the OM611 engine include:
- Intake Manifold Failure
- Injector Nozzle Washer Failures
- Crankshaft Failures
- Fuel Pump Leaks
- EGR Failure
- Alternator Pulley Failures
- Thermostat Failures
- Glow Plug Failures
- Fuel Pressure Regulator Failure
We briefly covered the common Mercedes OM611 engine problems, now let’s further elaborate on them in detail and learn more about when and how they appear. In addition, we will learn how serious these issues are and the symptoms they produce.
Intake Manifold Failure
One of the biggest failure points of these engines is the intake manifold. Why is this the case?
These intake manifolds are all made out of plastic. Diesel engines tend to run pretty dirty and carbon deposits start to stick to the flaps of the intake manifold.
Eventually, the carbon deposits will prevent the flaps from opening and closing correctly or even completely seizing.
In this situation, you will have trouble running the engine and the engine will stall on some occasions if the flaps are blocked.
In some situations, these flaps can completely break apart and start to produce rattling noises.
What many owners do is to completely replace the intake manifold of their engine or they simply remove all of the flaps and run the engine like that.
It might run a bit richer and have poor fuel economy. But this is one of the downsides of this mod. So, we wouldn’t recommend it. Get a used manifold if you can’t afford a new one.
Nozzle Washer Failures
Another very common problem with this engine is the burnout of the washer under the injector nozzle. This issue is commonly called the CDI Black Death – we talked about in our review of the OM648 engine.
This is mainly caused because people do not change these washers. They should be serviced every 60,000 km if you want to avoid having issues with them.
These washers should be changed together with the injector mounting bolt. Whenever this is not done at 60,000 km, the gasses will break into the channel that is under the nozzle.
By doing so, over time, soot will collect and the nozzle will be cemented to the cylinder head. And removing it can be a real pain.
The removal of the injectors can be very expensive and very difficult to do since these injectors will be practically sealed up completely with the cylinder head.
That’s why, replace the nozzle washers on time before problems become too serious and expensive.
Crankshaft failures were also noted, especially on Sprinter vans. This problem happens on the 2.2L version of this engine.
What happens is that the engine often can spin a main bearing or the crankshaft can fail completely. Both situations can total the engine.
This was reportedly caused by poor oiling and also poor maintenance. What is recommended is that the owner should upgrade the oil pump with a more efficient oil pump with two gears.
People often take the oil pump from the OM612 engine and upgrade their OM611 with this better-performing oil pump.
And if you have a Sprinter van with the OM611 engine, you should do the same in order to avoid engine failure.
High-Pressure Fuel Pump Leaks
The high-pressure fuel pump is another major failure point of this engine. So, what is an HPFP?
A high-pressure fuel pump is a special pump designed for the common rail direct injection system. This special system needs a huge amount of pressure for injecting diesel. This is why special fuel pumps were installed on all of these vehicles to do this purpose.
And what most of these first-generation high-pressure fuel pumps do is often fail. They fail and start to leak fuel everywhere.
This can lead to an engine fire in some cases. This is why if you have problems running the engine and you smell diesel, it is important that you check under the hood and make sure that you replace this HPFP.
EGR failures were also noted on these engines. If you don’t know, the EGR is the gas recirculation valve. This emissions device is installed on all diesel vehicles and some gasoline vehicles as well.
What it does is redirect some of the exhaust gases into the intake, thus, reducing NOx particles being released into the atmosphere.
And this EGR is a real pain for a lot of people out there. Whenever the car reaches 100,000 km, the EGR will clog up and stop working.
This will result in many running issues and check engine light. The only way around this issue is to replace the EGR with a new unit or if possible to clean the EGR and hope for the best. But most likely, you will have to replace the unit.
Alternator Pulley Failures
Alternator pulleys can also fail more often on these engines compared to other engines. The alternator pulley is a simple idler pulley that is mounted on the alternator.
This pulley is spun by the drive belt and then the shaft inside of the alternator spins, so you get power generation and the battery is able to charge.
Luckily, replacing it is not very expensive. Symptoms associated with this are squeaks coming from the serpentine belt or alternator.
The thermostat can also fail often on these engines. The thermostat is a simple device installed on the engine that allows the engine to circulate the coolant in the cooling system.
It is basically a switch that turns on and off. Unfortunately, this thermostat can fail and whenever it fails, the engine will either run really cold and will be very difficult to get up to temperature, or will possibly overheat.
Luckily replacing the thermostat is a really easy and straightforward job.
Glow Plug Failures
Glow plug failures are also common on these engines. And the worst problem is not the failures but the removal of these glow plugs.
These plugs have a service life of about 60,000 km and if you don’t replace them on time, they will become one with the cylinder head.
The only way around this problem is to drill them out if they don’t want to come off. And this can be expensive. So, keep this issue in mind whenever you are dealing with one of these engines.
Fuel Pressure Regulator Failure
And last but not least is the fuel pressure regulator sensor. This component, as its name implies, regulates the fuel rail pressure. This component is very problematic on these engines and can cause a lot of problems.
Whenever this sensor fails you will have a check engine light, loss of power, poor engine work, and hard starting issues. Replacing this unit will sort out the issue.
Which Models Have The Mercedes OM611 Engine?
Now let’s take a look at which models have the OM611 engine.
- 1998 W202 Mercedes Benz C-Class 200CDI, 220CDI
- 1998 W210 Mercedes Benz E-Class 200CDI, 220CDI
- 2000 W203 Mercedes Benz C-Class 200CDI, 220CDI
- 2000 W90x Mercedes Benz Sprinter 200CDI, 220CDI
- 2011 Force 1
- 2017 Force Gurkha Xtreme
What Are The Common Mercedes OM611 Engine Problems?
Common problems with this engine include issues with the intake manifold flaps, nozzle washers, glow plugs, EGR, high-pressure fuel pump, fuel pump regulator, crankshaft failures in Sprinter vans, thermostat failures, and alternator pulley failures. Most of these are common diesel issues.
Is The OM611 Engine Reliable?
Yes, this engine is pretty reliable and can be pushed up to 500,000 km. It has proven itself to be a reliable workhorse in Sprinter vans. Even though its oil pump is not as strong as it should be, that’s why we think that you should upgrade this part if you don’t want to spin a bearing and destroy the crankshaft.