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When it comes to bringing diesel passenger cars back to the North American market, Mercedes-Benz is in the forefront. An inline six-cylinder common-rail diesel engined with a Diesel Oxidation Catalyst was first introduced in June 2005 with the premiere of the E320 CDI (W211). The E320 BLUETEC introduced the OM 642 V6, which succeeded the OM 648 in 2007 Model Year. While this engine does not make use of the additive AdBlue®, it does make use of a Diesel Particulate Filter (DPF), a Selective Catalytic Reduction Catalyst (SCR), a Diesel Oxidation Catalyst, and a NOx Storage Catalyst. The Bin 8 diesel is the name given to this.
Although it is not a BLUETEC, the OM 642 was also offered in the GL, M-, and R-Classes. This diesel engine is a BIN 10. These cars, which were branded as 320 CDI, come equipped with DOC and DPF, but lack SCR. Ultra Low Sulfur fuel is also necessary for them.
Several overlapping strategies are needed to clean up diesel emissions. The production of N0x is lowered when the compression ratio is reduced and the EGR is extremely high. The leftover hydrocarbons are burned by a "regular" oxidizing catalyst. Clean up the soot with a particle filter. In order to convert nitrogen oxides into nitrogen and water, Tier 2 Bin 5 vehicles from 2009 use an SCR catalyst in conjunction with urea injection. What does it all mean for the Independent Mercedes-Benz repair facility, and how does it work?
Rotation of Exhaust Gas
EGR is where we should start. There is no combustion potential in exhaust gas recirculation (EGR) gasses since they are oxygen low. Reduced peak combustion temperatures are achieved through the displacement of the oxygen-rich air-fuel charge by inert gas. As a result, less nitrogen oxides are produced. When EGR gas flow rates between 30 and 50% are used, intercooling them makes them even more effective in lowering N0x production.
Similar to gasoline engines, exhaust gas recirculation (EGR) gasses have a tendency to deposit carbon on surfaces they come into touch with. Because cooling EGR has a tendency to precipitate out acidic chemicals, which would normally stay gaseous, the problem is made worse. A stainless steel intercooler that is resistant to corrosion is Mercedes-Benz's solution. A diesel engine already has a lot of heat to dissipate, and intercooling just makes things worse. The best way for independent Mercedes-Benz repair shops to keep cooling systems running smoothly is to clean the EGR channels and valves.
A second problem with exhaust gas recirculation (EGR) and diesels is getting the EGR to go into the intake manifold. EGR gas cannot be drawn from the exhaust into the intake due to the lack of manifold vacuum. An electronic control module (ECM)-controlled electric throttle was installed by Mercedes-Benz as a solution to the problem of on-demand manifold vacuum. Diesels that are subjected to high levels of exhaust gas recirculation (EGR) are likely to foul their intake manifolds, and cleaning them may be necessary from time to time to maintain their optimal performance and avoid sticking throttle valve actuators.
Engine gas recirculation (EGR) valves, lift sensors, intercoolers, mass air flow sensors, and throttle valve actuators are all standard on the new V6. After the throttle valve actuator, the cooled exhaust gas recirculation (EGR) gasses are employed. During EGR operation, the ECM is informed about the amount of EGR flowing into the engine by the lift measurement, and it is also informed about the amount of fresh air flowing into the engine through the mass air flow sensor. This is useful for determining the injection volume.
One way to find out how much DPF regeneration is to use the differential pressure sensor to monitor the amount of backpressure before and after the DPF. Both spontaneous regeneration and regeneration induced by the diesel ECM are possible, depending on whether the DPF temperatures near burn-off. Inadequate driving time to conduct a successful regeneration can lead to problems. Overloading the DPF and setting off the MIL are also possible outcomes if this happens repeatedly. During a test drive, the technician can use SDS to induce regeneration to occur.
In the beginning, there were two versions of the BLUETEC technology: the NAC+SCR system, which was approved by 45 out of 50 US states (Tier 2 Bin 8) and met Euro IV emissions criteria; and the AdBlue® system, which involved injecting urea (see to the sidebar for more information). All fifty states' Tier 2 Bin 5 emissions standards will be met by the 2009 AdBlue® vehicle model year. Both systems necessitate the use of ULSD fuel, which was the norm in the United States between 2005 and 2006.
In both systems, carbon monoxide and unburned hydrocarbons are "combusted" as they travel through a Diesel Oxidation Catalyst (DOC) as exhaust exits the engine. The NOx Absorber Catalyst (NAC) follows, which is responsible for removing and capturing nitrogen oxides. While the engine is running lean, NOx is stored in the NAC. When the engine is running rich, which may be achieved by adjusting the fuel injection, the NAC regenerates and a little quantity of ammonia is released into the exhaust. One step further in the NOx reduction process, the Selective Catalytic Reduction (SCR) catalyst stores the ammonia for later use. Despite experts at Mercedes-Benz having high hopes for NAC+SCR, the vehicle barely failed to meet 50-state emissions standards. Therefore, AdBlue®.
Since oxidizing catalysts are not novel, technicians shouldn't have too much trouble with them. That is not the case with a diesel particulate filter (DPF). Regeneration is necessary when the DPF has collected enough particulate matter and an increase in back pressure is noted. To regenerate, the exhaust temperature must be raised to a point where the soot that has built up in the DPF is burned into ash. Like a self-cleaning oven, practically.
Increasing the amount of fuel injected into the cylinders raises the exhaust temperatures. This very rich mixture will be transformed into the extraordinarily hot exhaust flow required for DPF regeneration by means of the oxidizing catalyst. Regeneration is most effective when done at highway speeds, when the DOC and DPF are surrounded by ample airflow. That eliminates the possibility of setting fire to underbrush or bushes or giving any unease to the consumer. The motorist should be able to see through regeneration completely. However, drivers may have difficulties such as an altered engine "feel" or an increased idle speed. Regeneration could be a disaster if there was an oil or fuel leak, like a stuck injector or a broken turbo seal. A gasoline injector that seems dubious should be swapped out.
The exhaust stream is an inherently hostile environment, but it is necessary to place pressure sensors and other devices there in order to detect backpressure over the DPF, measure temperatures, and inject urea into the SCR. It seems to reason that these sensors should have a similar failure rate and code triggering behavior to the oxygen and DPF sensors found in gasoline engines, making diagnosis easier.
Biodiesel fuels, whether used properly or incorrectly, are another potential BLUETEC issue for independent service shops. It has been confirmed by MBUSA that using B5 biodiesel in CDI diesel would not void the warranty. Biodiesel needs to be oxidation stable to avoid deposits and corrosion, and it also needs to follow ASTM D6751. It is uncertain whether every B5 biodiesel that is sold at the pump complies with these standards, which could cause confusion among owners. Using engine oil with an API rating of CJ-4 is also necessary to keep ash from clogging the particulate trap, which is a related requirement.
Rapid Boot Technology
Diesels from BLUETEC include a glow plug Instant Start System (ISS) that allows them to get to operational temperature in under two seconds. You don't have to wait for the temperature to rise over five degrees Fahrenheit before you can turn the engine on. A module regulates the glow plugs, allowing them to be used in starting scenarios as well as any other circumstance when their use could stabilize combustion, including prolonged idling in very cold weather. As an example, "post-glowing" maintains the glow plugs heated for a short time after engine starter to accomplish cleaner running and less emissions. A separate module controls the current going to each glow plug, detects whether a circuit has been shorted out, and communicates with the ECM.
V6
Due to the diesel's massive 388 lb. ft. of torque (as opposed to 258 in the gas versions), the 2007–2008 E320 BLUETEC offers acceleration that is on par with the gas-engined E350 six cylinder. Just three pound-feet less than the E550 V8 is that amount. In contrast to the inline six featured in the 2006 E320 CDI, this engine is totally new.
There are four valves in each cylinder of the new 3.0-liter V6 diesel engine. An 83 mm bore and a "undersquare" 92 mm stroke are part of its construction. Cast-in steel cylinders support the aluminum block. To make the V-6 more uniform, a balance shaft between the banks of cylinders counterrotates with the crankshaft's speed. The intake and exhaust valves are operated by dual overhead camshafts in each cylinder bank. A double chain drives the intake camshafts, which in turn drive the balance shaft. The exhaust cams are driven by a gear on each intake cam.
At low loads, the engineers at Mercedes-Benz discovered that by restricting one of the two diesel intake ports per cylinder, they could improve combustion, which in turn reduced pollutants and fuel consumption even further.
With the Garrett GT20V variable-geometry turbocharger, Mercedes-Benz engineers were able to reduce pollutants and increase efficiency with a compression ratio of 16.5:1 (boost goes up to 29psi), even though many diesel engines have ratios higher than 20:1. A VNT, or variable-nozzle turbine, powers the turbo. The electronics of the engine adjust the VNT's vanes according to the load. For greater charge density, the intake charge is cooled via an air-to-air intercooler, which can reduce the air temperature by as much as 150 degrees Fahrenheit.
With its state-of-the-art Common Rail Direct Injection (CDI) system, the E320 BLUETEC maintains a fuel pressure of up to 23,000 psi. The BLUETEC V6's piezoelectric injectors can handle up to five injection events every combustion event, which is a substantial improvement over injectors based on magnetic solenoid technology. The so-called "Pilot Injection" events lessen the clattering sound of diesels by reducing the pressure and temperature spikes that occur during an injection.
First Impression
Who cares about performance now that emissions are a footnote? "This ain't your daddy's diesel," has been remarked by a number of automotive writers. Many consider the new diesels to be performance options as well as economy options due to the devastating torque they can deliver at low rpm. The new diesel engine's turbocharging technology makes it as fuel efficient as other manufacturers' full-size hybrids, particularly on highways. Whoever said "diesel" beside "sport" or "luxury" was completely out of their mind. Will buyers be able to discern that it is a diesel engine despite its low emissions, high fuel efficiency, and tire-burning torque?
Yes, it is correct. Even on a chilly winter morning, the engine's diesel-powered nature will be audible. Drivers rarely stop to consider, "I'm driving a diesel." while the windows are shut. Even with a turbocharged engine, there could be a little lag time between pressing down on the accelerator and the car taking off. Many owners of these full-size vehicles attest that the "diesel disadvantages" have been much reduced, rendering them negligible compared to the incredible gas mileage (up to 36 mpg on the interstate) that these vehicles are capable of.
Among the strongest reasons to "go diesel" with Mercedes-Benz, there is the fact that their BLUETEC technology, which includes AdBlue®, is already utilized in tens of thousands of commercial trucks across Europe, in contrast to the 50-state regulations that forced domestic manufacturers to retool and construct entirely new engines and emissions systems. Thus, unlike what seems to have happened with some domestic diesel truck owners, American consumers are not being asked to evaluate new pollution technologies.
How does AdBlue® work?
The injectable urea flavor offered by Mercedes-Benz is known as AdBlue®. When liquid urea is injected into the hot exhaust stream, it produces ammonia (NH3), which, when combined with nitrogen oxides (NOx) and nitric acid (N2), forms water and elemental nitrogen (N2), both of which are safe to drink and breathe. Companies can "virtually eliminate" all NOx emissions from internal combustion engines by injecting urea.
Utilizing a single "can," the AdBlue® technology integrates the diesel oxidation catalyst with the particle filter. A concentrated urea solution, commonly known as AdBlue®, is injected upstream of the SCR catalyst to supply ammonia. When ammonia is added to the SCR catalyst, NOx emissions are reduced even more than in the NAC-SCR system. The heated on-board tank that contains AdBlue® should be refilled every time the vehicle is serviced.
The estimated mileage for one gallon of AdBlue® is around 2,500 miles. A dash warning light will turn on and additional actions will be taken if a sensor detects a low level, according to the program's specifications. Diesel owners who neglect to refill it will not be tolerated by the EPA. A unique coupler allows the AdBlue® tank and refill container to connect, eliminating the possibility of accidental filling.
Being a Brand, BLUETEC
At first, Volkswagen, Daimler-Chrysler, Mercedes-Benz, and BMW worked together to develop diesel engine pollution management technology to satisfy the stricter particle and NOx regulations in North America and Europe. There was a "BLUETEC" outcome. Mercedes-Benz is the sole manufacturer of the initial consortium members that offers automobiles equipped with this technology with the BLUETEC logo.
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A 3.0 V6 dual turbo diesel engine, the OM642
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GoodWillHunt
- Posts: 50
- Joined: Mon Feb 02, 2026 8:37 pm
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davejacobs
- Posts: 42
- Joined: Mon Feb 02, 2026 8:34 pm
Or has something fresh emerged? And that article is from the United States, where cars often have different engines and layouts than their European counterparts.
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GoodWillHunt
- Posts: 50
- Joined: Mon Feb 02, 2026 8:37 pm
Excuse my hopeful thinking and typing. I found it and figured it would be helpful to know more about the OM642.
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ThomasWhited
- Posts: 56
- Joined: Mon Feb 02, 2026 8:42 pm
I can't believe this story is that ancient!
Commencing in the year 2010.
Thankfully, I haven't seen any production twin turbo equipment yet.
The cycles of updating single-variable turbo Blurrtech versions are already a pain.
Since the euro timing chain disaster would have severely damaged the 2.1 four-banger twin-stage turbo engine's acceptability in North America, an alternative configuration of the chain was introduced in 2012. In my capacity as a store owner, I find it to be really charming!
This specific V6 diesel has put MB in the "khack" in North America.
The diesel van market has seen a significant shift away from LR Discovery 1 models owing to issues with reliability, christmas tree warning light scenarios, limp modes, and a large number of consumers opting instead for Ford or Dodge. the product support at MB dealers is inconsistent and, on sometimes, outright fraudulent when it comes to parts and service.
Unfortunately for MB, the introduction of Ford's high-roof van coincided with the peak and most expensive period for ADBLURR problems, which soured the 2WD van market. Across the board for van specifications, Ford was outselling MB five to one when I last checked. Once introduced, the Ford Ecotech engine proved to be a hit for the automaker.
Naturally, no one knows the North American market better than Ford!
The (diesel E class) isn't exactly a best-seller among passenger vehicles, but then again, neither are vehicles powered by CI engines. I'll tell you the difference.
Coking up like that six-cylinder heave ho! is the reason why around 80% of the E class customers I've dealt with have gifted me 320 diesels. The diesel defectors' market share is dominated by Lexus.
As a Brit living in the US, one thing I quickly realized is that, as the original mother nation, we Brits THINK we know all there is to know about this enormous country.
(Except, of course, that we weren't!). Since they were the first Europeans to set foot in that area, the Spanish were
It was constantly said: "If it works here, it will work in Yankeeland" when I was working for Leyland trucks/buses and BRE Railbuses, the company that originally sent me here to work. Other European manufacturers have told me this, and you won't believe what happened next.
Actually, that's completely false.
In a similar vein, Australia—that place down under, the B/L product killer—is no exception. :not passing
It would appear that MB is perpetually embroiled in spectacular class action lawsuits in the NA region for poor this and bad that! The most recent one is Diesel Emissions.
Meeting Trump at the White House must have been a nerve-wracking experience for Angela Merkel.
Our Teresa, at least, got to walk delicately among the tulips
Commencing in the year 2010.
Thankfully, I haven't seen any production twin turbo equipment yet.
The cycles of updating single-variable turbo Blurrtech versions are already a pain.
Since the euro timing chain disaster would have severely damaged the 2.1 four-banger twin-stage turbo engine's acceptability in North America, an alternative configuration of the chain was introduced in 2012. In my capacity as a store owner, I find it to be really charming!
This specific V6 diesel has put MB in the "khack" in North America.
The diesel van market has seen a significant shift away from LR Discovery 1 models owing to issues with reliability, christmas tree warning light scenarios, limp modes, and a large number of consumers opting instead for Ford or Dodge. the product support at MB dealers is inconsistent and, on sometimes, outright fraudulent when it comes to parts and service.
Unfortunately for MB, the introduction of Ford's high-roof van coincided with the peak and most expensive period for ADBLURR problems, which soured the 2WD van market. Across the board for van specifications, Ford was outselling MB five to one when I last checked. Once introduced, the Ford Ecotech engine proved to be a hit for the automaker.
Naturally, no one knows the North American market better than Ford!
The (diesel E class) isn't exactly a best-seller among passenger vehicles, but then again, neither are vehicles powered by CI engines. I'll tell you the difference.
Coking up like that six-cylinder heave ho! is the reason why around 80% of the E class customers I've dealt with have gifted me 320 diesels. The diesel defectors' market share is dominated by Lexus.
As a Brit living in the US, one thing I quickly realized is that, as the original mother nation, we Brits THINK we know all there is to know about this enormous country.
(Except, of course, that we weren't!). Since they were the first Europeans to set foot in that area, the Spanish were
It was constantly said: "If it works here, it will work in Yankeeland" when I was working for Leyland trucks/buses and BRE Railbuses, the company that originally sent me here to work. Other European manufacturers have told me this, and you won't believe what happened next.
Actually, that's completely false.
In a similar vein, Australia—that place down under, the B/L product killer—is no exception. :not passing
It would appear that MB is perpetually embroiled in spectacular class action lawsuits in the NA region for poor this and bad that! The most recent one is Diesel Emissions.
Meeting Trump at the White House must have been a nerve-wracking experience for Angela Merkel.
Our Teresa, at least, got to walk delicately among the tulips