Hi MB experts,

I've searched around but haven't found too much information on this. I'm a long time lurker but definitely need to post this to gain some insight. This is on my dad's 2003 C230 Kompressor coupe. It has 53k miles on it, had service done since new mostly at the dealer with oil changes done in between by me.

He had a check engine light recently while sitting around idling in traffic, and the car stumbled. On my code reader, it pulled a code for misfire on cylinder 2. It sounds like it's a problem with the coilpacks sometimes, so I bought all new plugs and coilpacks and replaced them today.

When I pulled out plugs 1 and 2 though, they were COVERED in oil. To the point where another drop or 2 came off the electrode as I was pulling them out of the head. Looking down into the head, I can see the tops of the pistons have oil on them too. What I find strange though, is there is oil all the way up the threads too (see pic) which I thought isn't typical, as it would be the electrode area and the threads close to it that are covered in oil.

Plugs 3 and 4 were dry, and looked OK, maybe a bit dark but not horrible. I believe these are the original plugs, I don't think MB has replaced them on service A or B.

Coming from an M103 190e, oil on the plugs are typically from the valve stem seals. Is this the same issue on the M271 engine? The oil all the way up the threads of the plugs is making me wonder if the oil could somehow be coming elsewhere? Possibility of a valve cover gasket?? Maybe it's just wishful thinking... :o

Finally, a second picture is attached. I noticed this hose was NOT attached. It's a hose between the airbox and the head area. Is this that infamous $12 hose (which has been replaced by the dealer)? I put it back on and added a zip tie on it. Where does it go? I'm thinking PCV valve?

Any help greatly appreciated. And I found info on the cam magnet leakage and ordered the parts to fix that today. There was oil in the connectors...

 

look for my post about the same topic. i think its just oil spill. i have the same exact thing happen to mine. nothing technical.

 

I'm pretty sure you're referring to this thread: https://mbworld.org/forums/c-class-w...e-problem.html

Did you find a solution? Was it an exterior seal? It's been a good few thousand miles since I've even touched the oil cap so I didn't spill oil into that area, I know that.

Going for an italian tune up now... Maybe clean out some carbon.

 

had a independent shop check it and they said its common to the m271 and they said need to replace valves. i took it to the dealer and they used star diag and nothing. they said its was just spilled oil when doing oil change. notice the the plugs are wet from the outside only. and the oil is gold/fresh.

 

also my plugs exactly the same like those pics when i did my swap. i think i have pics somewhere. bhut i think its at benzworld..

 

My plugs were the same as yours..number 1 and 2 had oil all up the threads and 3 and 4 were mostly dry. I replaced the plugs. I still do not have a resolution for this problem.

I also had oil in the throttle body and the mass airflow sensor as well. I never have to add oil in between changes though, so the oil loss cannot be that significant.

 

When I took the plugs out I could distinctly see oil on the pistons, and the electrodes were dripping wet with oil. I have macros on my other camera, I can post them here later too.
Weird, I went for an italian tune up tonight, and when I got home the car threw a CEL and was running rough. Gotta borrow a code reader to deciper the code again. When I pulled plugs 1 and 2 out (the new ones), there was no oil now. None on the pistons either. Strange...

 

ChowBow: bro.. id say its just oil spill when doing oil change.. maybe the oil just dripped when you took them off when you changed the plugs. i was so scared also when i had the same thing. but my friend at the dealer said its just carelessness in oil change.. dont take it to seriously unless you feel theres a change in performance.

capt_paul: oil loss occurs in time.. go thicker on the oil.. im now using 5w40.. i was burning 5w30 at 8000 miles in between oil change intervals. when i switched to 5w40 it was a o k. just keep using mobil oil. and keep pushing the engine harder. someone once told me its not healthy to smooth drive an mb all the time. you have to push it to its limits once in awhile. when you do 100% you'll burn alittle oil.

 

Sputtering, stumbling, misfiring and CEL is a change in performance. Wouldn't you say so?

I'm not sure I buy the oil spill stuff. That said.. get the new code and post it up here and monitor those plugs.

 

No careless oil change. The engine is dust free topside of the spark plugs. It is only when you remove the plugs when you see the oil soaked on the plugs and pistons.

I always use a funnel when adding oil at the oil change and there is no external leaks on the engine.

I exercise the engine all the way up to redline at times and I do all the required scheduled checks. The car has about 62000 miles on it.

 

I'm at 56,300 miles and on the original plugs. Car runs great.

 

OK I checked out the code. P0302, cylinder 2 misfire. This was the same code I received before I changed out the plugs and coil packs. So essentially I'm back at square one.

I really don't think it's oil spillage from oil changes. I do them and I have never spilled. The most likely reason why there's no oil on the plugs I'm guessing is driving it pretty hard cleared up some carbon around the valves possibly? I dunno. My dad is pretty tame with it most of the time, probably never gets to WOT or high RPMs so there may be some build up.

I will keep checking out the plugs to see if I see oil on them and in the cylinder. For now there is still this issue with the misfire on cylinder 2. I also have no oil consumption on this car. At least in 4k miles, the MFD still says the oil level is OK.

Finally, that hose I posted above is the crankcase breather I think. It's covered in oil on the inside too. This should be for the excess blow by that feeds back into the intake. I think I'm going to buy an oil catch can and install it in between to see how much oil it catches.

So, any suggestions on the misfire on cylinder 2? It's only tripped at idle. Restarting the car fixes the issue but leaves the code of course.

 

Have you done a search of the forum on the head issues with the 03 M271s? Apparently fixed in "late 2004". I really hope that's not your issue as it's a costly repair.

 

Yeah I've seen some of those threads.... Doesn't sound like that will be fun. I'll probably do a compression test on it to see if cylinder 2 is leaking. Anything special about doing a compression test on an M271? I figure unplug the coil packs so they don't get any power, and pull the fuse for the fuel pump?

 

Update:

Did a compression test on the car today.

Cyl 1: 175psi
Cyl 2: 125psi
Cyl 3: 175psi
Cyl 4: 175psi

So definitely a problem with cylinder 2. I then did a wet test, added about a capful of oil into cylinder 2.

Wet Cyl 2: 150psi

So it helped a bit, but not enough to conclusively say it's the rings. I think if it's the rings it would shoot up 40-50psi with the oil. Another 25psi might be the valves? What do you guys think? I bought a can of Seafoam and I'm wondering if I should try it out to see if that will help it out. It it indeed is a bad head, maybe I have nothing to lose by using the Seafoam?

Advice much appreciated at this point...

 

Sounds like you have the dreaded M271 head issue. I don't know about your seafoam question, I've just heard members on here say it can be too corrosive for MB parts. I used it several times on an old Camry with good results. But that's an apples to oranges comparison.

 

Have a proper leak down test done - See results - then head off I'm afraid. Hope you don't have a broken ring? any ticking noises from the engine?

 

Conclusion... Dealer did a leakdown and boroscope. Exhaust valve was covered with carbon buildup. Head had to be replaced.

 

There are people who've used Seafoam on this problem with some success.
It will clean the carbon off the valves enough for it to seat.

But according to a local mechanic that used to work at an MB dealership, the real problem is that the valves seats end up becoming oblong over time, and the head has to be replaced.
The new design didn't go into use until the 2005 models.
One guy did a DIY over on benzworld, pics and all...still cost him like 2 grand.
And he's still rebuilding the head with the messed up design.

And another member proved that seafoam drastically improved his compression...
you got nothing to lose.

It's sad that this engine has so many problems, and again at the same time,
the M111 being in use for so long, was a major factor in my purchase decision.
I didn't want to be a Beta tester...MB should do something about this....

 

Do we have a production date that the new m271 head design went into cars...I read "Late 2004" but there is no date I can find...Can the engine number be used to cross reference?

Is there no luck with owners recouping losses for a production problem, if in fact it can be traced to known production quality? I know it is not a safety re-call issue...but this seems to a pretty popular and expensive repair...Is there anyway to try and avoid it?

I am sorry to hear you had to replace your cylinder head...

Thanks,
Jake

 

is this really true??

 

I did try some seafoam on it before having the head replaced. It didn't help unfortunately. Either way, if the head was redesigned later then the seafoam is a band-aid fix at best. Compression might have gone up a tiny little bit after the seafoam, but nothing to write home about.

Honestly I'm not that impressed with this M271. It does have a good amount of issues like the $12 hose, leaking cam sensors, bad coilpacks, and while those are easy to live with, the cylinder head going bad is a deal breaker. While we'll keep the car I couldn't recommend this model to someone else. Maybe an M112, but the W203 does seem to have a lot of electrical gremlins going on too...

 

In regards to driving it tame all the time...

Hard to say. I believe driving it hard sometimes does clear out some carbon build up and it should probably be done. While my dad won't drive the car too hard, I will sometimes take their cars out and get through some RPMs and make sure everything is pushed hard once in a while.

Although I also have a 190E with an old M103 engine... And it belonged to a family member who had never, ever, floored it. She's just a little old retired lady and drives to church and get groceries etc. I got the car off of her and it runs great and has no internal engine problems whatsoever. It's got some age related cracked hoses and broken sensors, but the bottom and top end are solid still.

 

Yeah, you should push your car from time to time. What can it hurt - even if it doesn't really help?

The 2005 M271 cars should all have engines that are free from the head defect that seems to plague the 2003s. Unfortunately, Chowbow, your story is not uncommon for the first-year M271 C230s.