john_eldorado

So doing some research, I want to protect my 2017 S550. Only has around 45k miles. Inspecting the factory connections for the wire harness on the sensors and solenoid, I see zero oil contamination or leaking. So a good sign.

I wanted to buy a full set of 8 pigtail connections that are supposed to break the potential oil contamination. FCP Euro only sells a set of OEM that only fit the solenoids (4 total) not the sensors? So it looks like the only supplier is some random ones on Ebay. Any guidance on what to avoid or good sellers? Some are way cheaper than others, but I have a sneaking suspicion they all come from the same Chinese factory.

I'm a little sketched out adding these, is there any chance it can cause interference in the electrical signals? I know for example that sometimes adding a universal O2 sensor, sometimes that can create an engine that doesn't accurately read the electrical values correctly and can cause drivability issues.

Also, I'll be the first to admit I'm no expert in physics or chemistry, but the idea of oil sucking through the copper wire all the way back to the ECU and causing 5 digits worth of damage, is this really confirmed or could it be more urban legend? It just doesnt seem very logical to me. If I didn't see so much chatter on the internet about it, I would be pretty dismissive.

waterzap99

I have looked around and asked around for the other four. No luck.
The oil can definitely go up to the ECU via capillary action. Its slow, wont just be in a few minutes, but it does do it over time.

When I cleaned mine out, some oil came out of the wiring. It had not gone up high, but it did go up a bit.
Once I replaced the sensors of course that process stopped. Then it slowly started to come back down.

I think the pressure of the oil inside the engine probably also helps push it up the wire.

john_eldorado

I'm just going to defer that it's a real issue since companies are cranking out kits to stop it and I doubt everyone is lying about it. Seems like even Mercedes had a similar fix for different engines? But why not this one?
This is Mercedes flagship, a $120k car when new. Have a recall for Pete's sake! This is supposedly catastrophic damage and it's happening at low mileage.

But I'm wondering if the reason Mercedes isn't recalling it is because they dont see it the way some people do? It just doesn't seem track with my logic on how this all plays out. Very little oil is coming out of these sensors and into the wire. The copper wire isnt an open "tube" and it isnt an airtight connection that pressure would move it. If someone was say changing the oil and spilled a little oil in the engine bay and on a wiring loom, very unlikely to completely ruin the whole wiring harness from oil being drawn through it.

But again, I'm not expert. I'm stuck with this car for a few more years, and it sounds like cheap insurance.

Now I have this and cylinder wall scoring to worry about.

Lexus is starting to look better and better to me, despite being boring cars.

PeterUbers

I've been using the eBay ones on my e63S without issue

john_eldorado

Thanks for the feedback.

Any seller you'd recommend or do you have a link?

waterzap99

Do you have all 8 that fit?
Only 4 fits for me

as.thompson

For anyone that has discovered this oil leak problem, how did it appear and what caused you to recognize it? Was it very obvious when looking at the wire harness or did it require disassembly to locate it? How many miles on the engine when the problem became evident?

waterzap99

Just unclip the sensors. You will see oil in the connectors. About 40k miles. Did not have any issues. Dont know how far up the oil got, but cleaned it out.
When you have issues because of the oil its too late.

Whatever oil is in there, if any, won't go any further as the ECU sits higher than the sensors without the oil supply through the sensors (I think).

The top 4 are easy to get to and easy to replace. 20 min job? 10 min? Dont remember, but quite simple

The bottom 4, little pancake ones are easy to unclip, but not easy to replace with out taking apart a lot of other things. Hours labor.
I did the big ones in mine and hope to never have to do it again.

You can get pigtails for the bottom 4, the big ones. Have not been able to get ones for the top 4. But again, they are easy to replace.

Sean._.S

Mercedes isn't doing a recall because this issue quite literally affects millions and millions of vehicles on the road today...

john_eldorado

I guess, but isn't that how recalls usually work? You correct a widespread defect, save your brand's reputation, and maybe even save your company money from a multi-billion class action lawsuit?
I'm already sour on Mercedes quality, I've owned several S-classes. I can't even imagine if I was given a $10k bill to fix this on a car with only like 60k miles.

This is probably $20 in parts and 30 minutes in labor. I would at least make it a TSB, or just make it a suggested repair even if the customer had to pay for it out of their own pocket. But I doubt a Mecredes dealer would be even allowed to do this repair.

It would be one thing if this was a VW Jetta, but this is a 6 figure flagship. Can we at least pretend the company gives a damn about its image?

rant over

HardmanGT

I just bought these. Haven't installed them yet but I don't anticipate any issues.

https://a.co/d/fJ5hWDH

95Sinned420

I just recently purchased a 2016 S550 and like you, also wanted to prevent having this issue. I checked all my plugs, luckily all were good and no sign of any oil in the connections. I noticed all the parts had a green dot on them, perhaps those parts were revised parts that fixed the issue (supposedly) on the newer engines. I haven't seen/heard/found anything with anyone having this issue that had later engines.
I went with FCP Euro OEM wires for the four solenoids. I actually ordered all new solenoids and magnets (surprisingly shares the same part numbers as the m276 engine). Ended up returning all the solenoids/magnets when I saw that mine didn't need them. I couldn't find oem wires for the magnets but saw that people had good experience with E-Bay ones. The ones I got from eBay were from a seller named craftsman-part, for $25.
I can say that the wires work as intended, the quality is up to par with the FCP ones. The extra extensions didn't cause any issues with the car and everything runs as if they weren't there. My only complaint is that these wires are longer than they should be, I mean, for purposes of tucking it away, it does get in the way a bit, but still hides underneath all the engine covers.

Now, you're wondering if this issue does happen? I can tell you in my experience, on a M276 (2014 E350), yes, it definitely can happen. The E Class I had, had this issue and the oil actually ran all the way to the ECU. I must have caught it early because there wasn't a crazy amount of oil in the ECU connection. It was just wet and oily when I removed the ECU connector. Didn't cause any issues yet. I sprayed the whole connection with electrical contact cleaner, liberally, cleaned the ECU pins and let everything dry before putting it back in. I verified with a paper towel over the connection that no more oil was coming out of it and then I proceeded with replacing solenoids and magnets. The oil only leaked out of the magnets and the solenoids were all okay. Funny how they make OEM pigtails for the solenoids but it seems more common coming from the magnets.
Anyways, with that oil leak experience on the m276, I did not second guess or chance it with the m278, even if MB did correct it for the later models.

Bigg Willi

Both my 2014 S550 sedan and my 2015 S63 coupe had oil in the connectors. My coupe had it on all 8 connections (4 position sensors and the 4 cam phasers). I bought all 8 extension harnesses off Ebay, I just went with the seller with the highest satisfaction rating. I bought new phasers and sensors from FCP Euro. The Install wasn't too bad but there are some bolts that were a pain to get to doing the phasers, just take your time. Good luck!