Extending ELW
Super Member
Joined: Jan 2013
Posts: 636
Likes: 29
From: MN, USA
C43 5.4, ML320CDI, Fords
The 642 engine is great, if one ever goes down it is going to be from improper maintenance or improper repair. I've been mb dealer tech since before this engine existed and have been the sprinter tech the last 5 years so I work almost exclusively on this engine, 40+ hours a week in and week out. If a shop is not clean when doing valley cooler repair, it can destroy the engine because there is open oil ports in an area that can have alot of dirt and debris and if anything gets in the oil ports it will lead to catastrophic damage. Using proper practices will eliminate a risk of this. Honestly alot of people's problems is service related also. Any new customer at work, #1 thing I tell them every time is use the proper MB oil! People do internet searching think they're using better oil etc etc etc, no, stop. These engines are complex and you're not going to engineer it better than Mercedes did. Wrong oil will stick your intakes and plug your dpf. Beware of taking them to independent shops, you usually spend more money to get worse result. Don't believe me? I get customers every day who have been to shops x y and z and paid to have a bunch of different things replaced (aftermarket, China quality mind you), only for it to be something I've seen 100 times. 1 hour of labor for diag at a dealer will go so much further.
With that said there is a reason I have 2 2008 diesels. Last year before the adblue systems. They can definitely cause expensive repairs. Yes they get a little better mileage but you have many systems that can and do fail. Nox sensors, scr cat, complete adblue system with pump, line, valve, heaters, control module and the extra temp sensors. All these components can and do fail. The nox sensors are very common and aren't cheap and should be done in pairs. And you don't get a spare tire with most cars with the adblue. I'm not saying don't get one, but be prepared to possibly spend some money at times especially with 09+.
With that said there is a reason I have 2 2008 diesels. Last year before the adblue systems. They can definitely cause expensive repairs. Yes they get a little better mileage but you have many systems that can and do fail. Nox sensors, scr cat, complete adblue system with pump, line, valve, heaters, control module and the extra temp sensors. All these components can and do fail. The nox sensors are very common and aren't cheap and should be done in pairs. And you don't get a spare tire with most cars with the adblue. I'm not saying don't get one, but be prepared to possibly spend some money at times especially with 09+.
