I'm working on my 2014 ML350 BlueTEC that developed the infamous oil leak. It's apparently a common issue caused by the oil seals on the oil cooler.
The oil cooler being installed in the worst possible place from a maintenance perspective, requires the removal of the entire intake system, fuel rails, and turbo - which further requires removal of the baffles and wipers to create enough room to work.
Well, the disassembly is now complete and the oil cooler was indeed swimming in a puddle of oil, so I'm glad to be fixing that...

The extensive disassembly involved in the process led to the discovery of another issue:
Most of the intake system - pretty much everything from the throttle valve all the way to to the cylinder heads - was full of sludge/grime.
I'm surprised the engine was still running seemingly fine considering how heavily restricted the intake airflow must've been. (Though I suspect performance may not be what it should be)

So my questions are:

1. What is the best way to clean out all the sludge?
   • I'm hoping someone can recommend an efficient, time-saving method of getting this all cleaned up.
   • All the parts that came off will be cleaned before going back on, but does anyone know of a better way than extensive scrubbing?
   • Is there a good way to properly clean out the intake ports on the cylinder heads without having to do further disassembly?
2. What can be done to prevent this from happening again?
   • The vehicle has 100K miles so I'm assuming it took a long time to get that bad but I want to avoid the problem entirely if possible.

Pictures:



 

Sea Foam engine cleaner is a good one. You may have to do multiple treatments and oil changes. One of the things that kills the OM642 is the long oil change intervals. You should do a change every 4k to 5k miles to be safe. Google how to clean sludge from a diesel engine for more information.

The bad news is that since you have so much sludge there is a good chance the engine is already damaged. There could be clogged oil passages that will cause extreme wear on engine components. Good luck with your engine. Not many on this forum have a good history with the OM642 and the Bluetec versions are even worse.

 

Thanks for your response. I will be doing 5K service intervals and will look into using Sea Foam to try clear any possible hidden build-up.
The engine hasn't experienced any issues yet aside from the oil cooler leak. I will be replacing the seals with the latest revision from MB.
There is no sludge in the oil - just extensive build-up in the air intake manifolds and associated parts. Pretty much everything between the throttle module and intake valves is lined with crud. This was discovered coincidentally as a result of the disassembly required to gain access to the oil cooler. Hopefully that means I'm dealing with it before it becomes a major problem. I will be thoroughly cleaning everything before putting it back together.

Now that I am aware of this, I'm trying to avoid a situation where extensive disassembly just for cleaning will become a future routine maintenance task.
I'll be doing more research into this, but I'd like to hear if anyone here has more advice on cleaning the air intake system and keeping it clean.

From my research so far, gunk building up in the intakes seems to be a disaster caused by direct injection + PCV + EGR. Whoever thought that dumping fuel + oil vapors and exhaust gasses into the air intake is a good idea ... probably no-one; unfortunately everyone does it due to ****ty environment regulations... The people who made those regulations should be executed and buried face-down: we all drive worse cars because of them.

So, I'm assuming that a catch can and an EGR delete will go a long way to keeping the intakes clean. Is this the solution I am looking for? Is there more that can be done?
With the impending recall, that will probably have to wait for now.

 

Yes, the idea of a catch can is a good one. Plenty of info on the X164 GL forum. Same engine so everything applies and the owners there typically have much more experience due to length of ownership.

 

I am about to take on this exact same task, plus injector seals and maybe even a preventive timing chain replacement as well depending on what I see. I too have 100K miles and I expect to see the same build up. I have read lots of threads already so I feel pretty confident of the process.
as to cleaning the crud out of the intake I think the scrubbing method is the best except it takes the longest. I have seen videos of other diesel intakes being cleaned by burning the stuff out with a blower after igniting with a torch but I would be very afraid of warping the intakes and damaging the swirl flaps. I have read that acetone works well as a cleaner, but I have had my best luck cleaning this black crud with a chemical called B-12 from the auto parts stores. It can be used as a fuel system cleaner etc like Sea-Foam and is similar but I have seen better results with this stuff. I dont know if they have it in your area.
All that said, the one suggestion I would make is that when you are trying to clean up the intake valves, make sure to rotate your engine (with a wrench on the crank) to make absolutely sure that the intake valve is fully closed before you try to scrape the crap off the valves. Then sucking all the crud out with a vacuum is a must. a small dental type tool works but of course this takes time as well. Being in a bent over position to tackle this job is something I am not looking forward to. I think taping off all areas of the motor where any crap can land and sink down into the motor is probably a good idea even though it will add more time to the process. I intend to have my wife driving a different car for as long as it takes for me to get this done rather than have to hurry through it. Waiting for much nicer weather at this point before I even start.
I also believe the recommendations of replacing that seal at the back of the valve cover for the PCV system is a must. The catch-can upgrade makes sense to me but I dont have any experience with those as of yet. However I have seen this same upgrade on various "hot rod" sites for other engines that seem to suffer from PCV related problems.
My long term plans include adding a small amount of detergent (something like Marvel Mystery Oil) in the oil prior to an oil change to try to reduce the overall amount of sludge in the motor. My biggest concern is of course moving the sludge that is currently stuck to the metal parts into the bores where it can lodge and plug like right at the main and rod bearings, which is what happens when people try to use a "mechanic in a can" to fix problems. I have had good luck but seen some not-so-good luck with this process. I am not recommending anything, just sharing experiences. Perhaps simply changing the oil more often is just as effective, as well as making sure the engine is fully warmed up, even "hot" if you will, before changing the oil. I live in a cold climate and I believe that more frequent oil changes in the winter are a good idea. Just as important is making sure the motor is fully up to temp to make sure the oil drains out well.
Just my 2 cents worth.

 

With all my respect, but...at MB ( Euro5 and 6 - 2010 and up - I don't know how Euro X can be assimilated for other markets), the problem with carbon deposit is only related with bad quality oil or air filter.

From W166 and up, the M642 oil cooler begin to loose oil after 300K km, here in EU.

But, if you use incompatible oil, you can change it several times a week.. and everything you stated will be quite appropriate.

Here, in EU fuel is very different and our experience for servicing premium diesels can help you as well.

With correct oil, changed exactly how Assyst calculate ( around 25K km) and with correct air filter ( exchanged only with Xentry help)...you will never find again carbon deposit and you will understand why is mandatory for you and especially for the rest of us to let the EGR or DPF exactly where MB installed.


The lubrication part of the oil, is not so important from long time.

Any oils, even the ones sold in groceries, can lubricate.

Only the premium ones can clean and can maintain the normal working temperature.

 

That is all true in Europe, but there is one other BIG contributing factor (and one other smaller one) to the large difference in reliability and problems these cars have in Europe vs. the USA: the quality of the fuel. Both the gasoline and diesel fuel that come out of any pump in Western Europe are MUCH cleaner than the garbage that comes out of the fuel pumps in the USA, both as a result of the inferior oil refining process as well as the agricultural government subsidies to corn and soy bean farmers and the resulting Ethanol and biodiesel content respectively in the fuel that produce different combustion byproducts and rapidly dilute the oil. Both the gasoline and diesel fuels in the USA are crap, and when you burn crap you end up with a lot more soot and other chemicals as well as unburnt fuel that end up in the oil.

The other (smaller) contributing factor is that in Western Europe the vehicles are inspected and maintained to a much higher standard than in North America. Car owners adhere to a more stringent prescribed service interval, and they also have to have a mandatory technical inspection performed at an independent facility every year in order to get their vehicle permit (sticker). Here people drag on the maintenance interval as long as possible, and there are no technical inspections need to be performed to get your vehicle permit renewed.

So - unlike people in Western Europe, Americans both put (and thus burn) garbage in their cars - which degrades the oil at a much faster rate, and they don't change it as often as they should - and don't do nearly as much preventive maintenance. That's why the diesels in America are ~20 times less reliable and prone to developing problems than the exact same cars in Europe.

 

...to strong words ..I work remotely with workshops in EU, USA, UAE...is exactly as you note " car owners adhere. ..".

Is true, we adhere, because ( at least at MB) is the cheapest way to take full advantage for this brand.

We use bio-diesel as well, I think this is not the issue. We have low-cost diesel as well....

Is only about demand...your market can supply of there is enough demand.


Also, MB knows very well the quality of fuel from US and set the engine management, accordingly.

 

The quality of the diesel fuel is indeed why Mercedes no longer sells diesel cars in North America.

Mercedes requires owners to use diesel with less than 5% biodiesel (B5), which is the blend available in Europe. Throughout the USA, the majority of pumps now spit out diesel with up to 20% biodiesel (B20). This higher level wreaks havoc on the engine, leading to expensive issues that are not covered by the warranty and/or result in premature failures right after the warranty has expired because people are using the wrong fuel.

“Continuous use of B20 fuel can lead to fuel filter clogging and injector deposits, and can cause the engine oil level to rise due to unburnt fuel washing into the oil pan. A clogged fuel filter as well as injector deposits can cause engine performance degradation while increased engine oil levels due to dilution by unburnt fuel can cause engine mechanical damage.” That’s a quote from a Mercedes pamphlet.

When you combine excessive engine oil dilution (because of the high biodiesel content) and long oil change intervals (because of the infrequent oil changes), you end up with the disastrous reliability of the Mercedes diesels in the USA.

Canada doesn't subsidize our soy bean farmers and our diesel pumps spit out B5, and we also don't have the Magnuson-Moss Warranty Act that basically says that you can use cheap aftermarket parts and that any unqualified person can service the car without voiding the manufacturer warranty so we take ours to the dealerships for service - and just like they are in Europe, those same diesels here are infinitely more reliable than they are in the USA. That is a fact.

 

MB doesn't sell diesels in the US due to low consumer interest. They did keep the Sprinter since it is a niche vehicle. Diesel accounts for less than 3% of the MB market in the US and significantly less than 1% of the total market. Then, there is diesel gate. MB is most likely completely done selling diesel in the US and has shifted focus on gas and electric vehicles. This is from and MB spokesperson and is not my opinion. I did adlib on the diesel gate comment but you can't help but think that is a big part too. They don't ever comment on pending litigation.

 

Well... that is only partially true. Statements from official spokespeople are usually 50% BS by definition because a PR department only exists for the purpose of spin and damage control.

Low consumer interest may be a contributing factor, but it is far from being the key reason for their discontinuation. There has ALWAYS been relatively low consumer interest in diesels in the US because the US is the only place in the world where gas is cheaper than diesel (because of artificial price manipulation, not because of production costs - diesel costs only about 60% as much to refine as gasoline, and is furthermore a lot more efficient as a fuel). Yet, even in spite of the price anomaly in the US, everyone was making and selling diesels in America until a few years ago and there was sufficient demand for it. Consumer interest may have indeed dropped, but it didn't drop for no reason. It dropped because of the massive reliability issues and problems, which are a direct result of the unusually high biodiesel content because of US corn and soybean production subsidies.

Dieselgate indeed had a lot to do with it. No one likes getting caught with their pants around their ankles, however, the dieselgate scandal applied equally to vehicles worldwide, not just in the US, and they are most certainly not discontinued elsewhere. Here's an article from July of 2019 from Mercedes titled "The diesel engine is fit for the future". They are apparently making even cleaner diesels now and are marketing them everywhere else except in the US, and European emission regulations are even stricter than they are in America.

Furthermore, brands that were not implicated still continue to manufacture and sell diesels in the US. You can still buy a posh diesel Cadillac Escalade, two diesel Range Rovers and a number of lesser Jeeps and GM SUVs. There are now more new diesel pickup truck models being manufactured and sold in the US by all three domestic manufacturers than ever before despite the fact that they cost ~20% more money than their gasoline-powered counterparts. If they can continue to make (and in the case of Land Rover, import) and sell diesels despite the fuel price anomaly, there is obviously enough interest.

So, yes, dieselgate definitely had a lot to do with it, but the real problem with why they are still selling diesels everywhere else EXCEPT in the US is with the fuel itself.

 

The main difference between EU and US is the taxation for fuel.

Here, 80% of fuel price is tax.

https://taxfoundation.org/gas-taxes-...on)%20on%20gas.

Besides VAT, in some countries road tax, etc, the Excise is calculated when the final product is ready to be delivered.
This way, the oil price or cost of technology is not so important, for final price.


Refinery, is one of the most important tax producer.


Only because of this, EU fuel price is 3-4 times higher than US.

Also, this taxation method, forced us to demand the most competitive and fuel efficient engine's.

The same for suppliers, investing in technology for efficient engine's and good quality fuel, become the only way to add value.

But, greedy and maybe some other reasons too, culminated with Diese Gate.


​​​​​​I don't know if the EU taxation method is good or bad, at one hand it helps technology ( fuel and engine's) and on the other hand it creates a impossibility to use electric energy for electric cars...as applying 400% ( 80% tax from final price means 400% added tax from oil/rafinerry fuel price) tax over the electricity KW price will make this technology very hard to be consumed.


Daimler claim this:

https://www.daimler.com/innovation/d...el-debate.html

 

Too many mis-statements to address, so I just highlighted the worst ones.
Example - "diesel costs only about 60% as much to refine as gasoline" was true before ULSD was required in 2006. Not any more. ULSD requires 97% reduction in sulfur which is an expensive process, with new investments in refinery equipment. Also, with the loss of sulfur, additional Lubricity additives are now needed, which adds to that production cost.
The price at the pump varies based on demand and weather impacts on refineries - sometimes higher than gasoline and sometimes lower.
The US essentially adopted Tier 6 emission requirements a few years ago - no longer different.
Biodiesel is AVAILABLE here and there, but it's actually unlikely that you can find it in most locales, and then it's clearly labelled. I don't use it.

The biggest reliability problem has been the use of excessive EGR, an emissions technique that has essentially been replaced by SCR's and DEF. That's why the engines now last longer and have almost double the power and torque than a diesel from 15 years ago. Unfortunately, EGR is again required by the Tier 6 standards, but in significantly lower amounts, and manufacturers have been able to ameliorate its effects with additional treatments.

BTW DEF was developed through a M-B/VW/Peugeot consortium, that introduced the technology in 2010-11. It's a good thing.

 

Sorry, but that is simply not correct.

If you look at the configuration of a fuel refinery, much more equipment and processing is devoted to gasoline production than to distillates like kerosene and diesel. First, everything goes in the crude distillation unit (CDU), which separates the various "cuts". It then goes into the cracking units (FCC, hydrocracker, delayed coker) which transform the heavy oils into lighter products, but the complex as a whole generates more gasoline-range material than distillates, so more of the costs for those units can be attributed to gasoline. After the CDU, distillates like diesel only have to be hydro-treated to remove the sulphur before they are ready to be sold. Gasoline on the other hand, in addition to the same hydro-treating process to remove the sulphur, undergoes additional processes like isomerization, catalytic reforming, alkylation and finally component blending in a separate processor before it is ready to be sold. So sure, while the removal of sulphur in diesel introduces an additional cost, so does the removal of the sulphur in gasoline.

Low sulphur, high octane gasoline is the most expensive to produce by far. That doesn't even include the higher federal taxes on diesel vs. gasoline nor the higher subsidies for blending Ethanol in the gas vs. blending bio-diesel in the diesel. Yes, the diesel prices vary seasonally because of demand as it is also used as heating oil, but even in the middle of summer diesel in the US is still more expensive than gasoline. In comparison, diesel in Canada and Europe is cheaper than gasoline even in the middle of winter. It still doesn't change the fact that US gasoline is under-priced or that diesel is overpriced when compared to each other.

As for the bio-diesel content, regardless of what the EPA specifies at the federal level, some ~40 states now have state-level subsidies and incentives for retailers to sell diesel with a higher bio-diesel content than the federally-mandated B5, and the vast majority of diesel pumps in the US indeed spit out anything from B6 to B20. As an example, Iowa offers retailers selling biodiesel blends containing a minimum of 5% biodiesel (B5) a state income tax credit of $0.035 per gallon, and blends containing a minimum of 11% biodiesel (B11) a state income tax credit of $0.055 per gallon. If you want the regulation regarding what comes out of the pumps, it reads "Ethanol-blended gasoline must conform to ASTM D4814, E85 must conform to ASTM D4806, and biodiesel-blended fuel containing at least 6%, but no more than 20%, biodiesel must conform to ASTM D7467. Additionally, biobutanol must be an agriculturally derived isobutyl alcohol that meets ASTM D7862 for butanol for blending with gasoline for use as a motor fuel. Gasoline blended with biobutanol must conform to ASTM D4814. The state defers to the U.S. Environmental Protection Agency for potential changes in specifications." If you can find one single shred of evidence that this is not the case, I'd love to hear about it as I am sure would many other members on here that bought the Mercedes Bluetecs in the USA.

As for the emission standards, I have no idea what you've been reading and where, but passenger vehicles in the USA are subject to Tier 3 standards that are not even fully phased in yet. The Tier 3 emissions standards are about 20% more restrictive in NOx pollutants than the EU Euro 6 standards, but the Euro 6 standards are about 400% more restrictive in GHG pollutants (CO2) than the Tier 3 standards. In other words, the Euro 6 is about the same in NOx but 4 times more stringent in CO2 than the Tier 3. So - this most certainly does not explain the reliability problems. If "the biggest reliability problem has been the use of excessive EGR, an emissions technique that has essentially been replaced by SCR's and DEF", then that same problem should also be prevalent on European vehicles which use exactly the same EGR system, not just on the the US ones - which is most definitely not the case. So no, the presence of the EGR system is not the culprit or it would be failing in equal proportions in Europe and in the US. Actually, cars in Europe need to be tested annually for emissions whereas in the US everyone is *****ing and moaning about how much it costs to maintain them and a large percentage of the population is putting in emission system defeat devices, so if anything there should be twice as much *****ing and moaning about these failing in Europe as they do in the USA. That is clearly not the case. Yet, the diesel cars (including their EGR systems) in the USA are indeed failing ~20x more than they are in Europe. Why? Because all that biodiesel thickens and gels up at lower temperatures much more readily than petroleum diesel, which is a known issue, and furthermore because the biodiesel is much more likely to oxidize (react with oxygen) to form a semisolid gel-like mass. Add to that the fact that bio-diesel is both a solvent and has higher lubricity which causes it to end up past the piston rings in your oil sump and dilute it until it is no longer able to provide protection for the engine, and you have the resulting mess -- with US vehicles ONLY.

 

That was a long answer that misses my points. Your description of the cracking process is basically sound, and I haven't visited a refinery in years.
I don't want to argue about various e-standards in the World, but you are still quoting stuff from the early 2000's - the EGR days, which I agree were engine killers. Just like the smog pumps of the late 60's. We have moved far from those days in technology, and most importantly, engine life.

AND you are talking about biodiesel, which I agree is politicized and not good at all (my bigger complaint is the high water consumption of corn crops and the cost to produce). But it's hardly forced on most of the U.S., and I can avoid it on almost any cross-country trip.

I think you are railing against biodiesel, a point with which I heartily agree.

I apologize for my short summary of diesel e-standards compared to EU, and your comparison is mostly true, (I should have said Tier 5 not 6) but the EPA considers our current standards to be equivalent to EU Tier 5. There are several overlaps and slight differences in language. Part of the reason is attempts to standardize world-wide standards with as little modifications, one country to another. Bosch is the leader in that standardization. (Well, also M-B and now Stellantis.)

There is little evidence that I have seen of diesel engine failures in the EU or the U.S. since DEF hit the scene.

Some think that the pollution problems in, say, Paris, are because of some reason such as poor fuel or lackluster e-standards, but the truth is: Paris long ago invoked strict e-standards that caused the price of delivery vehicles to skyrocket. As a result, the fleet average age went from @8 years to over 20 years, and the engines just wore out, with the resulting high pollution, especially particulates. Bad strategy for Paris. They should have had a more gradual phase-in.

But, since 2006, our fuels are no longer "c**p." Even before that, though, we had the choice of Premium Diesel, which I always chose. Started better, ran cleaner, less rattle, less smoke, better economy and power - worth the Premium. Now, all we can get is the Premium Diesel equivalent, and I don't agree with your claim.

Diesel is also no more expensive at the pump than mid-grade gasoline.

 

I always thought that EU fuel is different, but it seems is not.

This is tuner, point of view,

https://www.etuners.gr/fuel/

 

My only point was an attempt to explain the discrepancy between the failure rates of the Bluetec diesels in the USA vs. the rest of the world, which are (a) the relatively high biodiesel content of the diesel fuel sold in most US states, and (b) the relative lack of regular and preventative maintenance of the vehicles.

While I have absolutely no issues with any form of cleaner and/or renewable energy sources, if the car someone just bought can reliably run only with a diesel fuel that has less than 5% biodiesel content and most pumps in the state where you live put out anythign from 6% to 20%, that is indeed a problem. To make matters worse, all of this is buried in the very fine print both in the cars' manuals and on little stickers on the pumps. The vast majority of people buy a Mercedes thinking they just bought a premium vehicle that's going to reliably run for a long time, and they are disappointed when expensive things start to fail after a relatively short time. That's all.

As for premium diesel, the only difference between it and the regular stuff are the additives and the cetane number. Neither one matters in how quickly your oil is going to get diluted as it has nothing to do with the biodiesel content in the fuel, in the same way that regular vs. premium gas has nothing to do with the Ethanol content. If you have a gasoline powered car with a submerged fuel pump that uses the gasoline for lubrication, the pump will last for 20+ years if you use Ethanol-free gas but only a year if you use gas that contains 5-10% Ethanol. By "crap" I mean high biodiesel or Ethanol content with all the negative side effcts of the same on the vehicles it is used in, not that the fuel is otherwise dirty. It is simply unsuitable for the cars that Mercedes brought to and sold in the US market.

 

That only takes into account the octane ratings, which are indeed about the same (and so is the sulphur level and the additives). Where they do differ is in the Ethanol - and in the the case of diesel, biodiesel - content percentages. While there are absolutely no issues with either Ethanol or biodiesel from a performance perspective, there are some implications on vehicle reliability if the vehicle wasn't specifically designed to take into account the higher biofuel percentages.