Mercedes Direct Injection engines - carbon buildup

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This is a topic that has intrigued me for a few years. MB has had DI engines now since 2013 in series production in use in the US/Canada.

We all know that DI engines suffer from excessive carbon buildup on the intake valves. We know that DI engines generally shred engine oil viscosity due to fuel dilution due to our [censored] gasoline.

Here's the thing though.

MB and its owners on various forums have indicated that MB doesn't have the issue. However, I've never seen a photo of any intake valve in a MB engine in recent years that either confirm or deny the statement from MB that they don't have this problem.

Can anyone point me in the right direction when it comes to photos or any info indicating that MB has or has not fixed this issue?

I'd also love to see a UOA or two of MB engines in recent years that are direct injected. Thanks gurus from BITOG!
 
AFAIK, what you've heard is a few years out of date. Most manufacturers are doing just fine with their DI systems these days. Tunes, engine oils, and various engine design features have all improved. DI is still more prone to carbon deposits than PI, but the problem is now mild enough that it's not going to be an issue for most people.

Mercedes-Benz was a very late adopter of DI. They implemented it long after other companies had mostly sorted out its initial problems. I wouldn't be surprised if their DI engines had no major problems with carbon buildup.

Have you tried browsing or searching the UOA section for what you're looking for?
 
Originally Posted By: vgliou
This is a topic that has intrigued me for a few years. MB has had DI engines now since 2013 in series production in use in the US/Canada.

We all know that DI engines suffer from excessive carbon buildup on the intake valves. We know that DI engines generally shred engine oil viscosity due to fuel dilution due to our [censored] gasoline.

Here's the thing though.

MB and its owners on various forums have indicated that MB doesn't have the issue. However, I've never seen a photo of any intake valve in a MB engine in recent years that either confirm or deny the statement from MB that they don't have this problem.

Can anyone point me in the right direction when it comes to photos or any info indicating that MB has or has not fixed this issue?

I'd also love to see a UOA or two of MB engines in recent years that are direct injected. Thanks gurus from BITOG!


Well the M276 engine was in the 2012 E350 which started production in 2011.
 
Originally Posted By: d00df00d
They often do. I'm reading that it's much better now with ULSD, though.


How do you fix the problem on a diesel?
 
Have 180,500 miles on my 07 BMW 335. I think I'm finally about at the point where I need to pop the intake off to clean the ports. I'm not sure this problem has ever been as big as it's been made out to be.
 
Originally Posted By: d00df00d
Mercedes-Benz was a very late adopter of DI.


DB was a very early adopter of DI - the ME109 had it in the '30's.
 
Originally Posted By: antonmnster
Have 180,500 miles on my 07 BMW 335. I think I'm finally about at the point where I need to pop the intake off to clean the ports. I'm not sure this problem has ever been as big as it's been made out to be.


Lexus was pretty bad. I've seen pics of nightmares in early VWAG designs.
 
Diesels don't suffer IVDs as bad as petrols because they have no throttle plate so plenty of airflow to sweep stuff away.
Petrols nearly always pull vacuum so on closed or partial throttle the inlet tract is filled with PCV and EGR hence the deposits.
 
Originally Posted By: motor_oil_madman
Originally Posted By: d00df00d
They often do. I'm reading that it's much better now with ULSD, though.


How do you fix the problem on a diesel?
Disabling EGR & running it hard both help (keep short trips to a minimum, work the engine hard occasionally).
 
Originally Posted By: Olas
Diesels don't suffer IVDs as bad as petrols because they have no throttle plate so plenty of airflow to sweep stuff away.


Mazda BT50...diesel.





Mitsubishi Triton, 4M41....diesel.

 
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Originally Posted By: Dyusik
Originally Posted By: antonmnster
Have 180,500 miles on my 07 BMW 335. I think I'm finally about at the point where I need to pop the intake off to clean the ports. I'm not sure this problem has ever been as big as it's been made out to be.


Lexus was pretty bad. I've seen pics of nightmares in early VWAG designs.

Very few things are as bad as the Internet makes them seem.
wink.gif


There were nightmarish examples from every manufacturer in the early years. But I do get the sense that VAG accounted for most of the problem at first. No surprise there; almost all of their engines were DI starting in MY2006, whereas DI only started trickling into BMW's engines in... MY2007? Whether or not VAG's implementation was actually worse, they just had a lot more DI engines on the road early on, so it's no surprise that they were the first and biggest source of problems.
 
Originally Posted By: rooflessVW
Originally Posted By: Eddie
VAG ?

Volkswagen AG

AG = Aktiengesellschaft, a German word for a public limited company.

Yup. Used as a general term for Volkswagen and the companies under the same umbrella (Audi, Bentley, etc.).
 
Originally Posted By: bullwinkle
Originally Posted By: motor_oil_madman
Originally Posted By: d00df00d
They often do. I'm reading that it's much better now with ULSD, though.


How do you fix the problem on a diesel?
Disabling EGR & running it hard both help (keep short trips to a minimum, work the engine hard occasionally).


Which negates the purpose of DI saving fuel (if you have to drive it WOT at times).

Any chance we can stay on topic here? DI engines for MB (and yes, I should have mentioned gasoline).
smile.gif
 
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I always thought VAG = Volkswagen Audi Group

Anyways, I did a bunch of digging into the Benz direct injection before I bought ours, and also found no evidence of the issue. I would be more than happy to get a UOA at the end of my next interval (this fall) if you are interested in helping fund it. My filter was OEM, and the fill was PP 0w-40.

Something interesting about this engine is that I can pull the oil fill cap with the engine at idle, and there is no change at all in how it runs. With my wife's last car (BMW X3) if I did that, it would stumble and run very rough. I don't know the PCV routing on the Benz yet, but I am guessing it is something a bit different, and perhaps that is why they don't have the issues. When I get the time to dig into it, I will try to remember to post what I learn.
 
Originally Posted By: DriveHard
I always thought VAG = Volkswagen Audi Group

Anyways, I did a bunch of digging into the Benz direct injection before I bought ours, and also found no evidence of the issue. I would be more than happy to get a UOA at the end of my next interval (this fall) if you are interested in helping fund it. My filter was OEM, and the fill was PP 0w-40.

Something interesting about this engine is that I can pull the oil fill cap with the engine at idle, and there is no change at all in how it runs. With my wife's last car (BMW X3) if I did that, it would stumble and run very rough. I don't know the PCV routing on the Benz yet, but I am guessing it is something a bit different, and perhaps that is why they don't have the issues. When I get the time to dig into it, I will try to remember to post what I learn.


Yes sir, please - that would be fantastic. I'd like to see if it shreds engine oil like my 2.0T FSI from VAG.

And yes, I too thought VAG = VW Audi Group. Oh well, live and learn
smile.gif


I'm most interested as well to see how the MB engines handle fuel dilution and if there's a sharp drop in flashpoint. That may contribute to increased buildup on the intake valves due to PCV etc...
 
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