Where is all this oil coming from?
 

I have 1999 C230 with a CEL and P0170 code, which points me to the Air Mass Meter sensor. So I removed the AMM to clean it with CRC MAF cleaner. It was soaked with oil. The pipe coming from the air cleaner also has oil all over, and one of the large hoses coming into the air cleaner box is coated with a black tarry film.

I sprayed the sensor down with the cleaner, and now the engine runs better (for now), but where could the oil be coming from?

Some line is clogged, maybe even your PCV valve. That hose feeds hot air into the air filter area during warm ups, either directly from the crankcase or from the manifold area. My sincere apologies, I just don't know about the specifics of your motor

Check crankcase oil level for over-fill.

Thanks for the advice (this is a great forum!). I checked the oil level a couple of days ago. It's due for a change, and at the moment, it's about a quart low, so I assume that rules out overfill (or does it?).

Maybe I should look for the clog that ASaltyDog mentioned.

That rules out over-fill, but if the oil is ready to change and thin/low, you may have a little blowby [ specially w/kompressor], so an oil change may just do it..
I would start there and monitor it..I would also check the condition of the air filter.

chances are as mentioned above the pcv system is malfunctioning, the oil seperator is likely not working properly, large black unit on pass side of valve cover area

Just an idea
What about valve stem seals?

not likely, how would it get into the airintake system? if it were the seals it would go directly into the cylinder

These all sound like great leads. I'll take a look at the oil separator (and attached hoses) tomorrow morning. Actually, I replaced it a couple of years ago, so I didn't suspect it, but maybe something is clogged. I'll let you know what I find.

after you clean all the oil out of the intake pipes you may need to remove the intake, when i did it last I saw that the vacuum ports for the pcv valve were connected to each pair of intake runners by a notch in the plastic intake. I cleaned everything out good( I had to force a piece of wire through the vacuum ports to clean them) and put it back together. The breather system then will work properly and no more check engine light.

Sorry for the long delay, it was the holidays. I cleaned out the oil separator and all the connected hoses by blowing air through them. Is that good enough? None of the hoses seemed to be clogged. I also changed the oil, so may that will help.

Carson357 - I'm not sure I follow what you were doing. Did you mean to remove the intake manifold to get to the vacuum ports or ??.

By the way, I haven't located anything that looks like a pvc valve, and my AllDataDiy account does have anything on it. Does this car have one, or is that what the oil separator is all about?

Yes, it does have a pcv and the intake has to come off to get to it( at least if you treasure your sanity). The start of all the oil problems is usually the vacuum port ( two of them) gets stopped up and this causes the pcv to stop functioning. If you don't want to keep buying mass airflow sensors, you'll need to take the oil separator,supercharger,intercooler,and all related hoses off and clean them out. If you don't, all the oil will work its way back up to the MAF. The oil separator is pretty cheap, you can just replace it. The intercooler willprobably need to go to a radiator shop to get all the oil out. Everything else can just be cleaned out with carb cleaner. By the way, the pcv hoses will be hard as a rock(top two),so it's easier to cut them and replace them with the new pcv.Just be sure to clean the vacuum ports out with a wire or something. Hope this helps.

Ok, now I'm going into a bit of shock. Let me get this right; I have to remove the intake manifold to clean out the vaccum ports. To get it off, I have to remove the air intake, a wiring harness, the fuel injection rail and injector, and various electrical connectors. :bigcry:

Then, to remove the intercooler, I have to remove the bumper, radiator, and various other items. Sounds like a fairly big job, is there an easier way to clean it out?

I think I'll take it to my favorite mechanic. He's a great mechanic,but isn't a Mercedes expert. Are there some drawings or instructions that I can get?

the oil is coming from IRAQ....thanks to the war....lol.....


i liked ur title, " Where is all this oil coming from?"....couldn't resist

check engine light - midlothian va
 

just joined in order to check whether or not I'm getting the run around from the local Mercedes"expert" - less than a month ago they repaired a broken vacuum line, when the check engine light was reported to them during the 150,000 mile service. Two weeks later she began to stall and we barely got her back there. reportedly the crankcase ventillation leaked "somehow" and "stopped up", causing oil to shut down the air mass meter - this will have to be replaced (I'm glad I see the $300 above from last year) @about $388 (plus replacing a hose.

Anybody out there have experience with these guys? Did they screw up the crankcase during service last month? Or simply time for the crankcase to cause this? Any opinions?

Thanks