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M271 - oil in connectors?

183K views 170 replies 72 participants last post by  narutokaya 
#1 ·
I noticed a bit of oil in the O2 sensor connectors when I replaced them, yet didn't think much of it as it was only a small amount, cleaned them and installed.

My car has been needing < 1L of oil per 15K kms, nothing major, yet enough that I wanted to find the source.

Looked into other oil leaks on the W203 and saw the cam magnet sensors have leaked on the M111 causing oil to get into the harness.
I checked, and there's oil in the cam magnet sensors on my M271.

Luckily there no oil on the MAF sensor, or ECU connectors, so the problem might be isolated unlike the disaster it is on the M111 that ruins the ECU and requires the entire wire harness to need replacing.

Can someone do me a favor:
- pop the connectors off and look to see if there's oil on them.
- the magnets are circled in orange in this pic:
 
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#63 ·
That's just dirt & grime, there's no visible leak. What happens is the leak is in the bushing that seals the wires & connector, so the oil seeps into the harness. The only way to tell is to pull off the connector and see if there's oil inside the connector.
 
#64 ·
I popped the connectors off before I called the dealer. They were oily but not dripping. I've never seen the problem before so I snapped the pics and mailed them off. The service department made the decision to replace them. I'd rather put 400 miles on their car and not mine anyway.
 
#65 ·
Update: last week MBUSA issues a service campaign on roughly 60000 vehicles, including the c230 with 271 motor, c230 with 111 motor, and 170 with 111 motor for the camshaft solenoids leaking. This campaign will cover replacement of the camshaft adjustment solenoids, and installation of the adapter harness to prevent leaks from getting into the engine harness. It should also cover any damage that the solenoids may have caused such as oil in the engine harness or damage oxygen sensors. Also you may be able to be reimbursed if you have had to pay for this repair previously out of pocket and your vehicle is now covered by the campaign. So you may want to call your local dealer and see if your vehicle is included in this campaign.
 
#69 ·
the campaign number is 2009100001, it covers approx. 66113 vehicles. I am assuming these vehicles are all in the usa, but other contries may have a similar service campaign. Your local dealer can tell you if your vehicle is involved if you call the mand give them your vin number. I would also think that most owners should get a letter in the mail.
 
#71 ·
That service campaign could be great news. I just changed my downstream O2 sensor and I was like, hey, where is this oil coming from? Turns out is was inside the O2 sensor connector. I anticipate this issue will reoccur without corrective action. Sounds like the root cause is the cam sensor leak. I will call on Monday!
 
#72 ·
I just got my Camshaft Adjustment Solenoids and Install Adapter Harnesses replaced over the weekend, I had purchased the adapter harnesses last summer, and I was able to get them reimburse me for them! Just needed the receipt and they took the old harnesses! My old solenoids were not leaking and this is with 75K on the car now.

Funny thing and a warning; even in my garage the mice were able to construct a "home" in my air filter tube and housing. They were able to get into some of the car sound padding I have in the garage, and stuffed the air intake almost solid. I did notice a little drop in MPG, but holy cow I am glad the dealer looked. I will be fashioning a screen to the intake "horn"
 
#74 ·
Schumacher Mercedes in Scottsdale did the Cam sensor replacement per the service campaign. They even gave me a GLK350 for a loaner for free. I used that opportunity to pick up some new shelves that wouldn't fit in either of our cars. I didn't try to get reimbursed for the O2 sensor, because I got the new one on Amazon for $90 and they were already very generous with the loaner and a bag full of gifts.
 
#77 ·
I can't remember exactly how things went together, but since I installed the magnets first, I believe I just worked the round end into the magnets such that the round end would be facing the rear of the car. Since the plug is really just a cork in the hole, it probably doesn't matter. Look at the old ones you take out and that might give you a clue.
 
#78 ·
Thank you thehoodmeister!

I will try to figure which way it goes when I take the old magnet off. To me it's more logical to have the the flat end against the engine (rearward) as it won't pop out. Does anyone else who has this replacement done with the newer designed magnets and plugs know which way it should be? Thanks in advance.
 
#79 ·
If I recall correctly thehoodmeister is correct, the flat end should face the front of the car, I found it a lot easier to mount the plug into the magnet first, then mount the magnet. However your dealer should do the replacement for free since it is covered by the recent service campaign. I ended up replacing mine before the campaign and later took the car to the dealership where they refunded the cost for the magnets and they also replaced O2 sensors and the harnesses for nothing since the oil eventually travelled under oil pressure to other component before the new isolating wires were installed.
 
#80 ·
The dealer clearly told me that mine is not covered (2004 C230K), but for a different model year. What is your model/year? Anyway I installed the plugs with the round ends facing the engine too. The plug is pushed into the magnet prior to fitting onto the engine block
 
#85 ·
The dealer sucks in Canada, I think. I don't know about US. Service adviser doesn't know/care much. I showed this issue to them three times. They said don't pull something off the internet and ask the dealer. I pushed the issue as I don't feel comfortable with the slight oil leak and after the forth time, they did exactly what the internet is telling.

I feel that they know the issue and it is somewhere is their record but if the car is not throwing codes yet, they don't want to do anything. I think if my car is giving the codes it may be too late..

btw: they don't cover the cost somehow.. may be you have to insist that it is a recall..
 
#87 ·
I suspect I have a big problem with my wife's car. There seems to be oil everywhere! After removing the cover for the cam magnets they look worse then the guy who posted a couple pages ago. I will get around today posting my pictures hopefully by the end of today so you guys can give me your opinion.

I called my local MB, they said my car does not have any current service campaigns.
 
#88 ·
Don't take no for an answer....

Not sure where you are from but if your canadian than there will be no service campaigns as ther were only issued in the US.

Said and done it ended up costing us $5000 to get the car back in shape. Fought with MB canada and eventually they agreed to cover 50% of the replacement parts for the cam leak so that ended up costing us $3600 while MB covered $1700 in parts. After all the electrical was fixed up it was discovered that the rad was leaking internally and getting glycol into the tranny fluid, MB recommended replacing the rad, tourque converter and transmission... My dealer fought hard for them to cover this repair as it is also a recall item on US vehicles. In the end MB said no and we ended up replacing the rad and doing a 2x flush on the tranny, so far so good... car still has a rough shift from 1st to 2nd in summer mode but in winter it's not effected. Not sure I will ever buy another Mercedes, the wife likes her car and now I hope it is relitively trouble free. When it comes to German cars my experience with BMW has been far superior to Mercedes. MB corporate takes the attitude that they should not have to back thier product and if you can't afford to fix it then they don't need you as a customer...
 
#90 ·
Called one of my local dealerships and the 800 MB #, both asked for my VIN and stated there are no service campaigns for my car. I have a 2005 C230K, and I'm fairly certain I have a 271 engine,could they be giving me the run around? Is the campaign over? Does any one have the availity to verify what they are telling me is acurate?
 
#91 ·
I also have 05 c230k from US. they said no service campaign for it when they checked their database. they even printed it out for me.. may be only certain VIN is under the campaign...

you can try different dealer and see what they say but eventually most M271 suffers this problem..
 
#92 · (Edited)
My 2005 C230K has CEl on, and is pulling code P0136 - took connectors off at the cam sensors and they are quite oily. When I checked a few months ago, my dealer told me that the service campaign for that had already been done. I see no evidence of the wires being tied up, and obviously I am having some issues.

Guess I will call dealer tomorrow and see what they are willing to do. It sounds like some folks with 2005's are having trouble getting the dealer to assist with this, is that correct?

Any 2005 owners, would love to hear what your dealer was willing to do on this.
 
#93 ·
No luck with my 2005

Called two dealers and the MB 800 #, all told me that my car based on the VIN number did not fall under that service campaign. But the did tell me I could bring it in and give them $125 so they could tell me that they do infact need to be serviced.
 
#94 ·
I inspected the connectors for the O2 sensors (near bottom of engine) and found oil in the post-cat connector (pre-cat one was dry). Got in touch with the service manager at my local dealership, and he agreed to fix it even though it is technically not part of the campaign (wow!) so I am bring the car in tomorrow. He wanted to know the mileage of the car (it is only about 70K) and wanted to know if I have had the car into that dealership before (yes I had, for warranty work). Very pleasantly surprised. My advice on this is to just talk to service manager (not just the advisor) and to be professional and polite, not demanding and see what they can do. If they say no, fortunately for about $160 in parts you can stop the leaking at the sensors, and then for another $140 or so you can replace an O2 sensor. And both jobs are pretty easy to do.

Anyway, to fix it right, they need to change out the cam sensors, install isolation wires, change out post-cat O2 sensor, and they really shound change out the harness as well since it is contaminated with oil.
 
#96 ·
Wait, hold the horses. Above I mention dealer is willing to fix my 2005. Well, after taking it in, they say that oil has spread too far, supposedly into ECU connector and that it is too much for them to cover. Cost estimate is $3800 and they are only willing to cover $1100 of it. Includes new ECU, harness, post-cat O2 sensor, and the cam sensors and pigtails.

Ouch!!! If this was a 2004, my understanding is that would all be covered under the campaign.

So...I can either fork over the $2700 or I can get my car back and just replace O2 sensor and cam sensors myself, and try to clean the harness and connectors and hope the oil doesn't migrate farther. Not sure what to do.
 
#97 ·
Hello trelberg - Make sure you buy the Extension cables, which are supposed to prevent oil seeping down into the harness in future. Here is a video showing how to replace the cam sensors
You will need two sets of gaskets/seals. The parts department may or may not tell you that you need them. Good luck and keep us posted.
BTW - It assists other forum members if you complete your profile.
 
#98 ·
Great Video

Great Video! Good thinig I know spanish.

My cam magnets look like the picture a couple pages prior, I'm sure I have an issue.

Here's my question...

If I change out just the cam with the new wire which prevents oil from damaging other parts of the car, O2 senor. Would this at worse case be a good idea to limit damage, then at a later time proceed to repair the other parts that have got oil down stream?

Now per the video it does not seem to difficult to change the cam magnet. Where does the other end of the wiring harness connect to? Is it hard to reach?


Hello trelberg - Make sure you buy the Extension cables, which are supposed to prevent oil seeping down into the harness in future. Here is a video showing how to replace the cam sensors YouTube - MB C180K - Cambiar los electroimanes (W203 - M271)
You will need two sets of gaskets/seals. The parts department may or may not tell you that you need them. Good luck and keep us posted.
BTW - It assists other forum members if you complete your profile.
 
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