OM642 Longevity




What are the common failure modes for this engine?
What is the best maintenance to prevent them?
Obviously oil changes, decent fuel, not abusing it with overly short drives, not pushing it hard when cold, keeping the revs down, etc.
Fuel additives?
Oil additives?
Preventative maintenance? Chain early? DPF early? Etc ?
Auxillary fuel filter/water separator?
Auxillary air/oil separator on PCV system?
What warning signs to watch for?
Heres an example of a stuck om642 oil control ring. The top 2 compression rings are perfectly normal. This engine cold started and ran perfectly every time with plenty of power when it wasn't in limp home mode. The 3rd ring down is the oil control ring. Notice how it sits flush with the piston. On tear down 4 of 6 oil control rings were stuck. Owner complained of excess oil consumption for years (unknown amount), and getting stuck in limp home mode with DPF codes. The car was dealer maintained it's entire life on the dealer schedule. Dealer installed a new DPF at owners expense which also quickly clogged up. At 220k miles dealer told the owner it needed a new engine at which point he dumped it.
for comparison here are new rings. The piston rings are supposed to be springy, free to press up against the cylinder walls.
Last edited by tjts1; Mar 7, 2023 at 10:19 AM.




Common issue on them are oil cooler seals and intake flaps gumming.
Suppose the seals got updated in later years, but they are still not bulletproof.
For intake gunk, there are intake cleaners available. MB shop in Colorado gives good recommendations. for BG (?) cleaner, who require expensive injector.
I bought Liqui Moly cleaner and still have it on the shelf since all 3 of my Bluetecs run perfectly.
I mean main engines as emission systems are still weak point and lately I had $6000 jobs done on my Sprinter on DEF system.
$5000 covered by warranty and $1020 cash.
Last edited by kajtek1; Mar 7, 2023 at 11:32 AM.




if it was a gas engine I would fill each cylinder with solvent. Let it sit and then turn it over slowly a few times.
I don't know what to do with a diesel.
Guess you could do about the same, but would have to pull the injectors or glow plugs.
And I understand that also has risks.




Never heard about frozen piston rings from people who did use proper oils.
😂
Last edited by tjts1; Mar 7, 2023 at 10:49 PM.




Are stuck rings the high failure item?
What oil do MB dealers put in Sprinters?
I see a lot of commercial Sprinters getting service at MB dealers?
given that companies with fleets would more quickly notice correlation between MB service and failures, they must be doing something right.
If they use a CK oil, maybe 228.51, does it shorten DPF life, or maybe DPF replacement is seen like other service items and expected at some number of miles/years?
All that aside, other suggestions for longevity would be great.
Last edited by N_Jay; Mar 8, 2023 at 09:01 AM.
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When it was never investigated that far, some indication shows that 228.51 category oils dealers put in those engine, created phenomena turning oils into gelatin.
Modern diesels require much more than just lubrication from the oils.
The Best of Mercedes & AMG
Last edited by tjts1; Mar 8, 2023 at 12:03 PM.




When dealers denied any wrongdoing, the owners check that they most likely used the oil they had in bulk in barrels, not spending big money the 229.52 cost at the time.
Doesn't take much thinking what oils MB dealers used in bulk 5 or 10 years ago. At least for person who knows something about oils.




Last edited by tjts1; Mar 8, 2023 at 05:16 PM.




https://youtube.com/shorts/NArwYdVReUA?feature=share
Something doesn't add up?
CK-4
229.52
But more importantly, CK-4 oils are engineered for diesel engines, 229.52 oils are engineered for gasoline engines. Choose wisely.
Last edited by tjts1; Mar 8, 2023 at 09:11 PM.
https://losangeles.craigslist.org/lg...607853439.html




Recently my GL350 had a check engine light after period of time with nothing but short trips. I told my wife to take a trip on highway for a while and the light went away. I’m guessing these don’t have a separate DPF light?




Recently my GL350 had a check engine light after period of time with nothing but short trips. I told my wife to take a trip on highway for a while and the light went away. I’m guessing these don’t have a separate DPF light?
Does the MB just use the CEL instead of a specific DPF light?




Wrong oil - Stuck rings.
But it's not my fault 'cause I know more than MB.

MAybe he asked Sephens what oil to use.


Just use oils that are approved for 229.52 and you will be fine. I'm only just turning 160k miles, Don't burn a drop between 7500 mile OCIs.
Last edited by gone gone gone; Jul 3, 2023 at 10:43 AM.




Only in last years MB start installing DEF level gauges.
Turn out important as on some models DEF has heater above the bottom, so low fluid level would expose the heater, overheat and burn it.
On Sprinters the heater is integrated part of $3000 reservoir.



