When considering a used Mercedes-Benz, the 2007 E320 often comes into the conversation. Equipped with the OM642 3.0L V6 diesel engine, it promises a blend of luxury and fuel efficiency. However, from a mechanic’s standpoint, particularly someone with experience at benzxentry.store, the picture isn’t quite as straightforward. Having worked extensively on both the OM642 and its predecessor, the OM648 inline-6 found in earlier models like the 2005 and 2006 E320 CDI, a clear preference emerges.
The original forum post highlights a stark contrast between these two engines. The author, who owns both a 642-equipped vehicle and a 648-equipped one, expresses a strong leaning towards the older OM648. Let’s delve into why, focusing on the real-world implications for owners and potential buyers of a 2007 Mercedes E320.
OM642 vs. OM648: Torque, MPG, and Driving Feel
On paper, the OM642 might seem like an upgrade. It’s rated for higher torque and horsepower than the 3.2L OM648. However, as the original poster notes, “you’d never know it.” The OM648 delivers “torque beyond belief” and achieves impressive highway MPG figures, around 36MPG. The driving experience is described as effortlessly powerful: “The 648 just goes, and then it goes some more.”
The OM642, in comparison, is portrayed as needing “a bit more finesse” to find its power band. This suggests a less linear power delivery and potentially a less enjoyable driving experience for those seeking that signature Mercedes diesel torque. There’s even a suggestion that newer, smaller turbocharged engines might feel quicker than the OM642, which is a significant point for enthusiasts.
The Real Issue: Accessibility and Repair Costs
The core of the mechanic’s viewpoint isn’t about outright performance figures, but practicality and long-term ownership. Here, the OM642 engine falls significantly short. The original post bluntly states that the 642 “flat out just plan f-bombing sucks for access.” This isn’t just mechanic frustration; it translates directly to higher labor costs and more time spent on even routine maintenance. Imagine trying to reach components buried deep within the V-engine configuration – it’s described as a “ball of rubber binders wrapped all together.”
Conversely, the OM648, an inline-six, is lauded for its simplicity and accessibility: “the 648 is 60x simple to get to everything.” Inline engines are inherently more straightforward to work on, and this difference becomes critical when considering the maintenance demands of a diesel engine over its lifespan.
This accessibility issue directly impacts repair costs. The post provides a concrete example: a MAF and EGR replacement on the OM642 costing $800 in parts alone. The V-engine design necessitates duplicate components (two MAFs, two air cleaners, etc.), further inflating parts bills. And even after replacing parts, a trip to the dealership for diagnostic system (DAS) clearing might be necessary, adding to the expense.
Common OM642 Problems: Leaks and More
Beyond general accessibility, the OM642 has specific weak points mentioned in the original post. Turbo oil leaks from the MAF Y-pipe are a recurring issue if not “installed perfectly,” mimicking a main seal leak and causing diagnostic headaches. The oil cooler, nestled within the intake V, is another known leak source. These aren’t just minor annoyances; they are potential points of failure that can lead to significant repair bills.
The OM648, in contrast, is praised for its “rock solid” reliability, typical of inline motors. This difference in inherent reliability and ease of maintenance makes a compelling case against the 2007 Mercedes E320 (OM642), especially for those planning to keep the vehicle for the long term or perform their own maintenance.
Transmission Considerations: 7-Speed vs. 5-Speed
The discussion extends beyond just the engine. The original post raises a point about transmissions: 2007-2009 W211 models (including the 2007 E320) often have the 7-speed transmission, while 2005-2006 models have the 5-speed. The author notes that the 7-speed in their 2007 model “shifts a lot to find the right pull point,” whereas the 5-speed in the older model “just goes, fast.” This suggests that the older 5-speed transmission might be a better match for the diesel engine’s torque characteristics, offering a more responsive and less busy driving experience.
Brake System “Concerns”: A Matter of Perspective
The original forum post briefly touches on brake system concerns, dismissing them as overblown (“Chick-little sky is falling blather”). The advice is to “roll the dice” and suggests that actual brake problems on established 2005/2006 cars might be less frequent than online discussions suggest. While brake system reliability is always important, the author implies it shouldn’t be the primary deciding factor when choosing between these models, especially compared to the engine and maintenance considerations.
Mechanic’s Recommendation: Prioritize the OM648
Drawing from extensive experience, the mechanic in the original post clearly favors the OM648 engine. The concluding advice is direct: “For what I’ve spent on the 642, I’d take a 648 and electric brakes every day of the week and twice on Sunday.” The recommendation is to “find the lowest mileage 06” (E320 CDI with OM648) and “jump on it.”
For anyone considering a Mercedes-Benz E-Class diesel from this era, especially a 2007 Mercedes E320, this perspective is invaluable. While the 2007 model might seem newer, the older 2005 or 2006 E320 CDI with the OM648 engine could be a more reliable, easier to maintain, and ultimately more satisfying choice. The key takeaway is to look beyond the model year and understand the critical differences between the OM642 and OM648 engines under the hood.
