Engine running rough and no one knows why
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Junior Member
Joined: May 2015
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2010 ML350 Bluetek
Engine running rough and no one knows why
I have a 2010 ML350 Bluetek with 96000 miles. It has run great until now. While an a road trip it started running rough. I nursed it home. I have low compression in the #3 cylinder. I took it to a mechanic and at first he thought it was the injector. The injector was OK. After looking for a day he suggested I take it to the dealer 75 miles away from me. They claimed the problem was gasoline in the diesel and refused to touch it unless they change the diesel. (have you ever seen a diesel engine try to run on gasoline?) That was a huge waste of money and then they said it was the #6 cylinder. After 2 more days and me telling them it was the #3 they finally agreed but could not find the problem. There solution---tear down the engine at a cost of $4,000. No way I said. It runs real rough under 1800 rpm and smooths out mostly above that. I was forced to drive it about 300 miles with this problem. I am now back to the original mechanic who has years on MB. HELP! has anyone seen this before. Plenty power above 1800RPM. Real rough at idle.
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Joined: Jan 2015
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Mercedes ml350 w164 amg facelift
Sorry to hear that but you are not alone in the w164 nightmare I have mine on my long time friend euro car Indi and MB dealer for the pass year I think maybe 3months out the year it's have been at home I have only drive 20,000 miles in that sucker in 3years
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Joined: Apr 2014
Posts: 105
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ML 320 CDI
when was the last air filter, fuel filter, oil change ? has your intake manifold been removed/inspected recently (e.g. oil cooler fix). Crank Pos Sensor ? So we can eliminate those. Its not difficult to check gasoline in the tank. But it has to be drained completely. Tell us more on previous history how it led here. You might also want to check local Dodge/Chrysler/Freightliner shops who are experts in om642 troubleshooting. Good luck.
Thread Starter
Junior Member
Joined: May 2015
Posts: 17
Likes: 0
2010 ML350 Bluetek
when was the last air filter, fuel filter, oil change ? has your intake manifold been removed/inspected recently (e.g. oil cooler fix). Crank Pos Sensor ? So we can eliminate those. Its not difficult to check gasoline in the tank. But it has to be drained completely. Tell us more on previous history how it led here. You might also want to check local Dodge/Chrysler/Freightliner shops who are experts in om642 troubleshooting. Good luck.
Thread Starter
Junior Member
Joined: May 2015
Posts: 17
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2010 ML350 Bluetek
Thanks for the reply. I change oil every 5,000 miles (old habit). Filters etc are changed at suggested intervals. The engine has been inspected and tested by two dealers and one indy. Now we are getting ready to have an internal inspection. All I need is a lot of money to get it done. This happened suddenly. I was on the freeway on a road trip and it started running rough. I was about 100 miles from home. I live about 75 miles from a dealer so I have put some miles on it after the event. Above 1800 rpm it smooths out somewhat but below that it is rough.
Well, here is the scoop on this problem. The mechanic (independent) took the engine apart and found the problem. (1) excess carbon in the intake (2) The exhaust valves in the number three cylinder are not sealing due to carbon build up. Therefore this cylinder has no compression. (3) One exhaust valve in the number 2 cylinder leaking (carbon) causing a drop in compression. (4) An O Ring on the cam shaft is about to blow out. Therefore the whole cam shaft has to be replace. If this O ring were to blow out it would be a complete disaster. AND of course you can't just put in an O ring. You have to replace the complete cam shaft. THANK YOU MERCEDES! I need to know if this is common with this engine,I have driven MB diesels before for thousands of miles and never seen anything like this. I watch were I get diesel and follow the recommended maintenance schedule. I change my oil at around 5k miles. How does an engine like this build up this much carbon? I put 280,000 miles on a Ford diesel truck and never saw anything like this. Most of my miles are highway and freeway.
Is this a common problem with this engine and MB diesels in general???
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Joined: Sep 2012
Posts: 105
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W211
It is a common problem for direct injected engines. The fuel no longer passes through the intake manifold so it no longer cleans it and no amount of injector or intake cleaner will help. They normally remove the intake manifold and walnut blast the area of the valves to remove all these carbon build up.
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Joined: Mar 2011
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From: NJ
2008 ML320 (W164) - 201K Miles
Is there check Engine Light on ? if yes what is the code. If check engine light is not on, check your Wheel Bearing (Most likely Rear). Have your car on Lift and run while on Lift and see if you hear any noise. I was told that By Shaking Wheel we cannot find out wheel bearing is bad.
It took me more than a 6 month to find out this issue in my car and car was running very rough above 40 miles and it did not want to go any further. After changing Wheel Bearing in my both rear wheels, Car is running like brand new at 130K Miles. I wish I would have find out this problem much earlier.
It took me more than a 6 month to find out this issue in my car and car was running very rough above 40 miles and it did not want to go any further. After changing Wheel Bearing in my both rear wheels, Car is running like brand new at 130K Miles. I wish I would have find out this problem much earlier.
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