Recommended timing chain interval on OM642 & other buying advice.
Im looking at a 2015 GL350 with 72k miles. Purchase would be from a MB dealer who is going to be inspecting and repairing as opposed to a random secondhand dealer who doesn’t know the vehicle. Also a current and former owner of a few VW TDIs, one of which I discovered that running 100% biodiesel will clog the fuel filter (I was over 100 miles from home for that event lol)
I’ve done some research on these and reading the forums looks scary but it’s probably kind of a skewed perception. I ran a similar search on Honda pilots when mine was due and found a forum with a number of posts about ruined engines because of timing belt failures. A timing belt failure actually happened to my cousin’s Subaru Legacy at around 100k miles. So it’s not so easy for me to point and say the failure rate is exceptionally higher or lower among these vehicles. Although certainly pricey if it does happen.
Read up on the oil cooler and that seems to be a problem with the v6 diesels for quite some time. Need to keep a close eye for that.
Any advice about DEF selection? Might be hard to say but is there any information about preferred brands or ones to stay away from?
Biodiesel is the enemy. It has a higher lubricity than regular diesel, and a lot more of it ends up in your crankcase (especially during the DEF burn-off cycles). If you live in a state that has mandated anything more than B5, they're not the right tool for the job as it dilutes the oil too much resulting in all sorts of premature failures. Make sure you only use MB 229.52 approved oils, and change the oil at least twice as often as the prescribed interval (as in every 5K miles at the most). And, above all else, make sure that a diesel is the right choice for you... the diesels are workhorses and need heat. Driving the car mostly for short commutes is the worst thing you can do to a diesel engine. Running them for 3+ hours at a time at full load is where they really shine.
DEF is DEF - a mixture of 32.5% urea and 67.5% de-ionized water. Unless it is old or contaminated, it makes no difference which brand you use. Make sure you get it only when you need it and always use the entire container (as opposed to frequently topping it up) as it will crystallize when stored for prolonged periods as the water evaporates.
I did find where the post 2010 models had upgraded seals for the oil cooler so there is less concern about that.




Last edited by E55Greasemonkey; Jun 22, 2022 at 03:13 PM.




Last edited by E55Greasemonkey; Jun 22, 2022 at 04:43 PM.
And, they stopped selling diesels in the USA because the crap that comes out of the pumps there is 20% soybean oil - for which you can thank your politicians, not Mercedes, and because litigation is your national sport. From a mechanical standpoint, there is nothing wrong with the OM642. It is certainly a lot more reliable that the equivalent gas models. It's only when you put in garbage for fuel that dilutes the oil in 2000 km and drive it as a grocery getter when the engine never has a chance to properly warm up that problems start to arise. They still make and sell diesels in the rest of the world, and they make Sprinters with the same OM642 among other engines. Of the four Sprinter models that are available in the USA, three have a diesel engine... what does that tell you?
As for your friend, I also have a friend who happens to be one of the top three Daimler technical guys for all of NA, so I'll take my own experience and his word over yours. Unless you have any experience with the OM642, please stop bashing it.
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And yes they have strict, possibly even stricter, emissions standards than the US does. There are DEF pumps at the fuel station right alongside the diesel pumps. Although, their diesel fuel may be a bit higher quality if anything. I’m not sure of the diesel blends where I am so I will probably look into that.
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Last edited by E55Greasemonkey; Jun 22, 2022 at 11:51 PM.








And yes they have strict, possibly even stricter, emissions standards than the US does. There are DEF pumps at the fuel station right alongside the diesel pumps. Although, their diesel fuel may be a bit higher quality if anything. I’m not sure of the diesel blends where I am so I will probably look into that.




I am sorry to hear your experience has been that negative - mine thankfully hasn't, and moreover I know of a VERY few instances in Canada that have resulted in catastrophic engine failures (this is based on statistical information directly from MB Canada, not a second hand account or a handful of cars that people have brought in). Unlike in the USA, 86% of all W166 and X166 MLs and GLs sold here were the 350 Bluetecs, or roughly some 32,000 vehicles. In comparison, the total number of W166 and X166 diesels sold in the US was less than half of that. Yet, the only people *****ing and moaning about the OM642 are owners from the USA that have admittedly been dealt a bad hand with their biofuel subsidies and resulting biodiesel content - for which you need to blame your government, not Mercedes - and are either too stupid or too cheap to change the oil any more often than they have to in order not to void their warranty. They also don't seem to understand that a DEF heater that dies after 5 or 6 years of freezing and thawing cycles does not make the engine crap and is technically considered a wear and tear item. The OM642 has been around since 2005, and is still being made and used today as a diesel workhorse, not just by Mercedes but also by Chrysler. Name one other modern engine that has been in production for 18 years please. And, if you think the OM642 is problematic, you really ought to have a good look at the alternatives. Unlike, say, a DEF heater, a balance shaft or intake manifold is part of the engine - and how many of those have you had to replace on the M272s that you like so much? More importantly, how many of the M272s and M276s that you've worked on have well over 250,000 miles and are still going strong?
Are the diesels the right choice for soccer moms in the USA that use them to do 20-minute grocery runs, keep putting in B20 diesel and only change the oil every 9,000 miles? Absolutely not. Are they the right choice for a vehicle that runs continuously for more than a couple of hours a day (or for that matter, 14 hours a day hauling parts) or for towing a trailer? You bet they are. If you are using the wrong tool for the job (or are using it incorrectly), it's not the tool's fault - it is yours, but you seem to be completely oblivious of that and are instead bashing the engine instead of those that are misusing it or not looking after it the way they should.
Anyway - it is apparent that you don't understand what the causes of any of the reported issues with the OM642 are and that we're not even close to having a meaningful discussion of any sort on the subject, so I guess we'll just have to disagree on this one. Thanks for your valuable input.
- That Mercedes Benz makes a great product, and has decades of experience making great diesel engines for both taxicabs and trucks.
Further resolved:
- That the 2007 EPA ULSD diesel emissions regs were a gut punch to all companies making diesel passenger cars. As the owner of two BWMW 335d sedans, the MB engineering solutions are probably about as good as anything I have seen, unsurprisingly.
And, they stopped selling diesels in the USA because the crap that comes out of the pumps there is 20% soybean oil - for which you can thank your politicians, not Mercedes, and because litigation is your national sport. From a mechanical standpoint, there is nothing wrong with the OM642. It is certainly a lot more reliable that the equivalent gas models. It's only when you put in garbage for fuel that dilutes the oil in 2000 km and drive it as a grocery getter when the engine never has a chance to properly warm up that problems start to arise. They still make and sell diesels in the rest of the world, and they make Sprinters with the same OM642 among other engines. Of the four Sprinter models that are available in the USA, three have a diesel engine... what does that tell you?
As for your friend, I also have a friend who happens to be one of the top three Daimler technical guys for all of NA, so I'll take my own experience and his word over yours. Unless you have any experience with the OM642, please stop bashing it.
As far as DEF, I have been using (as DIY) BlueDEF. I have no complaints or issues. I have about 88k miles on a 2013....love the truck..Oil cooler replaced 2x under warranty and also new AC unit. it requires a little bit more maintenance than the other cars I have/had, but I tend to do most myself (brakes, filters, etc). Also, my understanding with these are that you want to change the oil and filter every 5k miles, but it is an easy change.
Hope this helps a bit and good luck
I’ll probably do my own oil changes and basic maintenance as I do with most of my cars. I would plan on doing it more frequently than recommended so long as I can remember without the notice.

Sure everyone knows this so newb bowing out.








They also have members who made 500,000 and even record is 700,000 miles without opening the engine, so I don't think you need to worry about chain on SUV with 70k.
Sprinters also have 20,000 miles oil change intervals, but they have much bigger oil pans. Bare in mind the same engines work much harder in "Barn door" sized Sprinter.
I just did lab test on my oil running 14,500 miles and changed it due to over 3 years of age. Here is the copy.








The previous oil change was done by PO and when I found the change mileage on ECU, I have no records what oil was used. Looks like it might be dino mix as there is no Molybdenum in it.
Also the Sprinter had sticker on windshield calling for oil change after 10k miles, what I ignored going up to 14.5k
Here is test from E250 for comparison. If I remember it right, the I4 in sedan takes 7 quarts of oil.
Last edited by kajtek1; Jun 25, 2022 at 03:12 PM.
The new engine is vastly smoother, more powerful, and quieter than the trusty inline five turbo. Whereas my woefully underpowered 300D would average around 27 mpg, the E-350 turns in 32 mpg tank after tank. (The car really shines on longer trips, and highway driving generally.)
And, yes, the engine is vastly more complex than the OM617. Of course, any V-6 is going to be more complex than an inline 5. I guess my question to OP is, what are the weaknesses specific to the OM642?
If you say CBU or EGR issues I do not disagree, but I am going to point you back to the EPA’s Tier 4 NOX and particulate regulations that took effect in January 2007, which threw everyone for a loop. (I have two BMW 335ds – both 2011 models -- and both have vastly greater problems with their emissions systems than my 2012 MB.)




When those jobs can be done with minimal parts cost, they involve lot of labor due to poor access and that is why lot of owners would rather hack the system and put resistor to fool computer, only to drive with clog intake.
But cooler seals got better over the years when Liquy Moly come with affordable intake cleaner.
I always like 4-cylinder diesel more for better fuel economy and easier service, but when I found Sprinter that I like with OM642 engine, I did not hesitate to buy it.
Sure mpg is poorer, but then I admire better torque. As you can see in the raport above - my Sprinter pass 200k miles and seems to be in excelent shape.
I am getting ready to replace alternator brushes.



