The bulletin would cover installing the jumpers, but not doing anything about the oil unless there were active faults. They don't deem the presence of oil alone to be an issue.

 

So the end of the matter is;

After trying 9 new Merc plugs from FCP,.. (A 004 159 81 02, with Bosch number Z6SII3320R stamped on the side)

then 8 Bosch plugs (ZR6SII3320)

and buying a single Merc plug from the dealer for $25 just to double check,.. (A 004 159 81 02, with Bosch number Z6SII3320R stamped on the side)

NONE OF THEM index correctly. All aim down to the 7 o'clock position.

SO I cleaned the iridium contacts of the old Merc plugs with 1,000 grit and then 2,000 grit wet-sand paper, then gap'd them down from 27 thou to 23.5 thousandths and re-installed them. Put a tiny wipe of Dielectric grease on the porcelain to make the coils easier to get off next time.

I also bought 4 of the sacrificial oil-block jumpers from the dealer ($45),..then cleaned the oil out of everything and installed them.

Purrs like a kitten now.

I have 4 new Cam position sensors ready to go in if needed,.. and have 3-4 different sets of plug-indexing washers on the way for next time. Hopefully in the next year or two I'll be able to figure out a solution for spark plugs.

 

Duckstu: It is sad to hear the current batch of plugs aren't correct for our engines. Good news on the oil in harness fix for yours. I guess I'll just have to see if my new dealer installed plugs start mis-firing... :-/

 

that's just crazy
thanks for doing all the work and checking this for us

so, what are we going to do about plugs?

 

Well, as PITA as this might be... You have to DIY or buy the plugs and then put the proper thickness copper gasket on, to insure the correct indexing...? I just have trouble believing MB would do this (tell its supplier to), unless there is a newer engine (series?) that takes the same plug and needs a different rotation... Bummer...

 

Well,.. I have a couple sets of plug indexing washers on the way, as well as another copper washer assortment like in my pic a number of posts up.

Indexing washers are made to go on the plug before,.(and in addition to) the normal copper washer. Problem is,.. this means backing the plug OUT an additional 2/3 of a turn. No biggie,.. but it might be better to go IN an additional 1/3 of a turn.

The way to do that is to replace the 1.5 mm copper washers that come on the plugs with some that are 1.0 mm thick. Less chance of leakage, and leaves the plug closest to the intended depth.

So I just gotta find 12mm x 16mm x 1.0 mm copper washers.

Hopefully the second time is the charm, and the set I have coming from Amazon is true to size. I'll report back here when I find a solution.

 

Update Jan 2021.

I got two more washer assortments in the mail today. The two on the right in the pic.

The set I got a few weeks back listed 12 x 16 x 1 mm washers, but in reality they only measured 0.7mm thick.

The two I got in today measure 1.0 mm and 0.91 mm.




So those two sets might be nice to have around when indexing plugs.

This is the one that measured 1.0 mm. ($12,50)

And the one that measured 0.91 mm ($18.89)

 

Stu, for oil in the harness, people are getting the V8 and V6 issues mixed up.

The V6 has cam magnet(circular caps on the end/front of cams on front of the heads, 2 on each head. This is the issue that has "jumpers" to correct the oil-in-the-harness issue.

The V8 had cam position sensors(the issue you found) that leak oil into the harness and the fix is to replace the originals with the newer upgraded sensors. Change all 4 of those. Oil can migrate into the harness and leach into the coil plugs, O2 sensor plugs and sometimes the ECU, causing catastrophic failure and totaling you car. Not trying to scare you, but this CAN become fatal. I had it in my Driver's O2 sensor plug, which caused it to fail. Found the oil when I was replacing the sensor. If you search here, there are several threads regarding these 2 issues.

Good luck.

 

Must be a pre/post-facelift difference, as both our '11 E350 and E550 have the harnesses installed.

 

It's also an engine difference. The 2010-2011 had the M272/M273 engines. Afterwards they went to the M276/M278 in 2012+. .

 

Ahh phooey.

I had ordered all 4 cam POSITION sensors from the dealer 3 weeks ago, but it turned out they ordered me the cam phase-rs instead.

Someone told me that THOSE were the problem the day before I picked them up,.. so when I saw the wrong parts at the dealer, I was actually relieved, and bought them. I haven't installed them,.. I just cleaned the connectors of old ones (which looked clean to me) and installed the 4 oil-block jumpers.

I'll check the cam position sensors. Those were soaked with oil before. If I see any in there I'll have to order up 4 new ones of those.

I'm amassing quite a collection of unneeded parts. At least the car is running spectacularly. I did the jumpers, cleaned all the electrical connectors, cleaned / polished and closed the gaps on all of the spark plugs, installed the intake spacers and air filter kit you sold me, and replaced the aux battery at the same time. And a week later replaced the ft brake rotors and pads.

The car runs AMAZING. Soo powerful and smooth. Cold idle went from a bit rough to just like my wife's '17 S class with the same motor and 12,000 miles.

 

yeah, the jumpers won't hurt anything, but the phasers are not an issue on the M278. As you noticed, the CMP sensors leak through the plastic and allow oil into the harness ther. Just cleans the ends real good(I sprayed mine with cleaner and used shop air to blow them dry till I saw no more oil...), replaced the sensors and left everything disconnected overnight, then recleaned the wires again before putting back together. I then checked the plugs a couple times a week just to monitor and make sure no more oil leaked out of the harness into the sensor/connector.

 

Glad it's running well.

So, you cleaned the old plugs and reinstalled them?

 

Yeah. (Post 27 above).

I cleaned the electrodes with 1,000 grit, followed by 2,000 grit. Then closed up the gaps from 0.027" to 0.0235" and re-installed them.

Of course I have 2 new sets of plugs sitting here that are already gap'd down,... so perhaps one day I'll go in there and replace then using the 0.9mm and 1.0mm washers I got in recently.


EDIT,
So on Jan 6 I returned the 4 cam phasers (magnetic adjusters) and bought 4 cam position sensors from the dealer (which is what I had originally ordered from them a month ago).

The two sensors on my pass side were again soaked with oil. The exhaust one on the driver's side was a bit wet, and the intake cam sensor on that side was dry.

I cleaned the 3 harness ends that were wet and replaced all 4 sensors.

Today (Jan 8) after 2 days of driving I checked the pass side ones,.. and both are bone dry. Progress !