OM642 Diesel engine excessive oil burning

Mihail Mechanic Rockville, Maryland Posted   Latest  
Question
Driveability
2009 Mercedes-Benz ML320 Bluetec 4Matic 3.0L (642.820) 7-spd (722.9)—4JGBB25EX9A497323
Excessive Oil Burning
Dpf Filter Cloggs Up Periodically

Dear diesel mechanics, I would appreciate if some of you who are experienced with Mercedes/ Sprinter/Jeep diesel OM642 engines can give me their opinion. I would be especially grateful if someone who has attempted to rebuild an OM642 engine can offer advice. This is my vehicle which I purchased used three years ago. I have changed the oil regularly every 5,000 miles with the correct MB 229.52 spec oil. I have also changed the air filter and the fuel filter. The vehicle had 109,000 miles at the time of purchase. Soon after I purchased it I noticed that the vehicle burns around 1qt. of oil every 800 miles. It got worse and is currently burning 1 quart every 250 miles. I have to clean the DPF filter every couple of months with the Liqui Moly wand and cleaning solution to keep it running. I have replaced the crankcase ventilation valve and the turbo charger with new genuine Mercedes parts to no avail. I have also flushed the engine twice with BG engine flush and once with LM engine flush chemicals hoping to dissolve oil segment deposits which made no difference either. The engine runs fine, chain does not clank/rattle at start up and no smoke comes out of the exhaust. My question is how prevalent the oil burning problem with the OM642 engines is and what are the chances it just needs new oil segments. I am deliberating if I should try to rebuild the engine or put a used one in. I have not been able to find much information on problems with OM642 engines burning oil. I am hoping it is because they are rare and I just had bad luck. Thank you very much for your time and help. All advice and reference info is appreciated. Merry Christmas and Happy Holidays! 

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Josh Educator
Greensboro, North Carolina
Josh Default
 

Was there any difference at all after engine flushes? It sounds more like a cracked piston issue than stuck rings.

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Mihail Technician
Rockville, Maryland
Mihail Default
 

The flushes made no difference at all.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

These engines are known for burning oil. Could stick a First Look Sensor in the crankcase an see if any particular cylinder has excessive blowby.

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Mihail Technician
Rockville, Maryland
Mihail Default
 

Great idea. May try to do that before pulling the engine.

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Mike Technician
Salina, Kansas
Mike Default
 

On cleaning the Def filter what are you using ? My understanding is that they have to be removed and cooked to clean then , also is some of our trucks roll off trucks is with a lot of idle time have problems with the Def system or,not runningit long enough to get heat,into the system. Then with the oil usage piston rings or leaking around valve seals ,

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Mihail Technician
Rockville, Maryland
Mihail Default
 

We use the Liqui Moly kit. it works pretty well. The kit has two bottles and it costs about $50. You also have to have the liqui moly wand and bottle to spray the fluids into the DPF. It costs about $300. You can google it and watch the video. We have used it several times and it works at least for a while. I agree that cleaning the DPF in an oven is more permanent solution.

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Isaac Owner/Technician
Hurdle Mills, North Carolina
Isaac Default
 

These engines are prone to high crankcase pressures. Measuring crankcase pressure with a pulse sensor, when compared to a similar displacement gas engine should be entertaining. Are you sure it is oil consumption and not a leaking oil cooler? Oil cooler gaskets have been updated 3x times. You can peak in the valley and see. If there is any wetness in the valley, you need to do an oil cooler…

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Mihail Technician
Rockville, Maryland
Mihail Default
 

I did the oil cooler seals a couple of years ago and replaced the intake manifolds too because the runners’ push rod plastic joints were worn out and there was a check engine light for the intake runners. There are no oil leaks. I sent in one oil sample for analysis and they told me there was excessive iron in the oil. I will email you later. Thanks for your willingness to help me further.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Wow only 1-2 qts every 10k miles,that's really good!! GM and many other manufacturers spec at least for gas engines is that 2qts or less in 2k miles is acceptable lol.

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Mihail Technician
Rockville, Maryland
Mihail Update
 

Thanks everyone for the good suggestions and information provided. I sent the DPF for cleaning and was told by the shop performing the cleaning that they removed 80 g. of ash which according to them is quite a bit for a small DPF as this one. They were surprised that there was no oil contamination after I told them the car burns 1qt. every 300 miles. Apparently the oil is completely burned…

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Mihail Technician
Rockville, Maryland
Mihail Default
 

I got the DPF back from the shop that cleaned it and installed it on the car. I reset the DPF adaptations and drove. The check engine came back with a code for plugged DPF within days. I checked the Differential pressure sensor reading and it reads the same as before the filter was cleaned which is about 65hPa = .94PSI. So the cleaning did not work I am $450 poorer for that. The shop has all the…

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