OM642 burning oil - anyone see issues with rings? - Page 3 - PeachParts Mercedes-Benz Forum

engatwork · #31 03-24-2019, 10:54 AM

Macon, Ga

Im using one of the higher end Autel systems and now that you mention it I can monitor it in a couple different places and on one of them it never gets out of spec. I'll go back and look again this afternoon. Will probably drop the rear most exhaust and see if it makes a different on numbers too.

engatwork · #32 03-24-2019, 08:21 PM

I'm learning all about the exhaust system on the Bluetec (without DEF). I disconnected the rear most exhaust from what MB calls the "front exhaust" (MB p/n 211 490 2020) and did not see anything change in regards to excessive back pressure code and continued to have excessive exhaust back pressure after DFT. Then I disconnected the "front exhaust" from what MB is calling the DPF and wowzer, that did the trick. Plenty of acceleration and boost and the pressure numbers were approximately 1/2 of what they were during the prior trial runs. After numerous WOT runs with the "front exhaust" disconnected there was no check engine light nor lack of performance but plenty of turbo boost just like it should be

.

I'm trying to figure out this exhaust system. The DPF (right off of the turbo) has O2 sensors on both sides and it looks like a temp probe in the center. To me this part looks like a catalytic converter then the muffler looking part of the "front pipe" has pressure sensors on both sides and a temp probe at the inlet. To me it looks more like the DPF but MB calls it front exhaust. Anyway it is plugged. I'm going to make an attempt to clean it. I did find it interesting that no fault codes came up once I had it out of the exhaust stream but I may not have driven the car enough. If I could be assured that the ck engine light would stay off I'd put a straight pipe in its place. Does anyone know exactly what is inside the "front exhaust" muffler looking part. If no one knows I'll let you know what I find sometime this week when I open it up. I've got a friend that welds boiler tubes for a living and will be recruiting him for my welding needs. I'm wondering if it is just a muffler with sensors to make the EPA think it does something similar to what VW had going on with the diesel issues (nice way of saying cheating)?

This is more confirmation the dealer really did not want to have anything to do with the car in my opinion. They did send me another, new DPF to replace the one they installed in Nov.

KrustyKustom · #33 03-24-2019, 09:46 PM

I have enjoyed you post, sometimes folks do not follow a problem up with what they are finding as they troubleshoot. The first device from the turbo would be the SCR cat ( selective catalytic reduction). It should have a Nox sensor before and after it along with a temp probe. Also you will see a DEF injector there which should be pulled and examined, checked for clogging. You can have that SCR cat steam cleaned with so-so results. But you should be able to get it breathing again.

Hopefully that new crankcase breather diaphragm stops the oil vapor, who ever ends up with this car should consider a oil catch can which would help with catching the oil vapor.

jcyuhn · #34 03-25-2019, 01:05 AM

Quote:

Originally Posted by KrustyKustom

I have enjoyed you post, sometimes folks do not follow a problem up with what they are finding as they troubleshoot. The first device from the turbo would be the SCR cat ( selective catalytic reduction). It should have a Nox sensor before and after it along with a temp probe. Also you will see a DEF injector there which should be pulled and examined, checked for clogging. You can have that SCR cat steam cleaned with so-so results. But you should be able to get it breathing again.

Hopefully that new crankcase breather diaphragm stops the oil vapor, who ever ends up with this car should consider a oil catch can which would help with catching the oil vapor.

This car does not have DEF, that started in2010.

I am under the impression that it is an oxidation catalyst right off the turbo, with the DPF further downstream. but it’s been a couple of years since I sold mine.

engatwork · #35 03-25-2019, 05:48 AM

As jc said, no DEF on this application. I think you are correct in your terminology too but MB calls the one right off the turbo the DPF. After everything is sorted plans are to drive the car some and see how quickly the DPF plugs between regens. If it happens quickly I'll go the catch can route. I was seeing it start to plug fairly quickly with the next device plugged like it is. You should have seen all the stuff that blew out during WOT with with the connection disconnected.

These engines have to breath. Power was pretty awesome with the connection broken loose after the DPF but some of the plastic downstream of its' discharge caught heck.

jcyuhn · #36 03-25-2019, 08:51 AM

Quote:

Originally Posted by engatwork

These engines have to breath. Power was pretty awesome with the connection broken loose after the DPF but some of the plastic downstream of its' discharge caught heck.

I can only imagine! Ours always ran fine with factory power levels, which are more than adequate in the U.S. Overtaking on a two lane highway was effortless.

DDAY · #37 03-25-2019, 12:09 PM

Now that the dirty air filters are replaced, you may not need to modify the system. It may work as intended once the exhaust system has been unplugged and cleaned.

engatwork · #38 03-25-2019, 01:24 PM

That is what I'm thinking. I'm going to watch oil consumption after resolving issues and if I don't see what could be considered excessive will leave as is.

jay_bob · #39 03-26-2019, 04:10 PM

So what’s going to happen to this car? Is the owner interested in selling it?

engatwork · #40 03-26-2019, 04:41 PM

She is not interested in selling especially since she found someone that can help without taking her to cleaners.

jay_bob · #41 03-26-2019, 09:03 PM

That's good she wants to keep it, I thought she bought a new car (post 28). If she changes her mind and wants to sell it, younger son could use an upgrade...I really like these OM642 vehicles and that W210 was made the month before he was born.

That OM642 engine gets a lot of cr*p on this forum, but it really is a good engine once the oil cooler seal issue is sorted.

I do as much of the work as I can myself without going to the dealer. I am constantly in and out of there for parts but have only a few times done a non-warranty service there.

engatwork · #42 03-27-2019, 07:27 AM

She did purchase a new Lexus SUV and was pretty upset when she found out it is going to be a cheap fix. It is actually a w211 bodied car.

I've come to the same conclusion regarding the viability of the OM642 engine and am even thinking of trying to pick one up in an E class one day.

jay_bob · #43 03-27-2019, 08:10 AM

Understood it’s a W211, my comment about the W210 was for the car my son is driving (see my signature block)

Some people have signatures suppressed in their settings so here is what I have at home for those who can’t see it

2014 ML350 Bluetec (wife's DD)
2008 E320 Bluetec (my DD)
2008 ML320 CDI (Older son's college DD)
1998 E300DT (Younger son's college DD)

engatwork · #44 03-30-2019, 07:48 AM

I'm going to test an oil catch can on this car. Now that the car is breathing like it should I took a 150 mile trip on the interstate to determine oil consumption. It went from the upper most mark on the dipstick before the run to midway between the marks after the run. Averaged 80 for 50 miles while getting 32.4 mpg. Nothing at all wrong with that part. To me it would make more sense to route the pcv vent to downstream of the turbo but what do I know?

jay_bob · #45 03-30-2019, 08:34 AM

Be really careful with the dipstick on these engines.

The MB specification from the manual says you have to wait 5 minutes after shutdown before reading the oil level. And you have to leave the dipstick in for 3 seconds before pulling it out again to read it. And obviously you have to be on level ground.

It is very easy to mistakenly overfill these engines.