Blkvip

socket extensions and swivels are key in doing plugs on the 4.7. did a S63 monh or so ago, given you have the tools its easy...just time consuming. doing mine soon. hoping the 4.7 has a bit more room than the 5.5tt.

mikenbrook

my Sarasota, Fl. Dealer wants $940, says it takes 4 hours labor. Totally absurd. That’s without coils.

juststeve

replaced mine a few months ago when I had a coil go south. didn't find anything fun of interesting about it. not looking forward to the next time it needs to be done.

juanmor40

MB dealer quoted $700 (Sep 2020) for the spark plug maintenance and that was it. Said thank you, but I can do that type of work (though I had not done spark plugs for @10 years)

Researched the videos, and found the one in post $4, bought
- 16mm socket with a swivel extension. My mistake, I got the 12" extension, instead of getting a shorter one (see spark plug driver's side next to firewall = PITA)
- Spark plug boot removal plier. There is a workaround with a string that I could fancy one day.

The most important advice includes:
- get familiar with how the locks on the coil's connector work, so it will be a breeze to disconnect the coils and not figuring it out as you go along.
- be certain the socket is magnetic and with a permanently attached swivel extension; otherwise, if it gets stuck in and you cannot see it and you will sweat it out. Do not ask me how I know.

With a stuck socket on the plug near the firewall, a nasty connector that refused to give out, and a trip to the store for another socket it took me about 2+ hours to do. If you do the most difficult one first, the next 5 are a breeze.

With tools, plugs, and the refreshment, I still kept $500+ in my pocket. That is a transmission service (something I would not even attempt to do), or else.

chassis

I found the driver's side (left side) spark plugs the most difficult because of the ECU bracket and vacuum lines in the area. I think this is why WIS says to remove the intake manifold (and replace intake manifold seals) to replace the spark plugs. Removing the intake manifold makes easier access from above, avoiding the ECU bracket and vaccuum lines.

I will replace spark plugs next year at 100k miles, and I will allow extra time for either full removal of the ECU bracket and possibly removal of a vacuum line, or go the WIS route and remove the intake manifold.

Fliplegend

I was quoted $650 by the MB Dealer in Manchester, NH just about a month ago. Of course, I'll be going to my trusty indy for probably half that price when the time comes.

juanmor40

Agree; however, touching the intake manifold is in my opinion looking for other problems. Your experience dealing with sealing, vacuum, and leaks is very important then.

Easy access perhaps, introducing another failure point in the way back is true as well. Though I agree that incorrect handling of the ECU connector and its harness could also bring problems.

I recall removing the ECU altogether as shown in the video (post #4), but I do not recall removing any vacuum line. Well, I will find out at @100K miles then.

chassis

@juanmor40 Removing the ECU is easy. Removing the metal ECU bracket is a challenge because the small screws to the engine block are behind other components. Also in an SUV the fender needs to be reached over. It’s a challenge.

You will encounter a vacuum line if you do this job.

juanmor40

Let me look at it over the weekend. I recall my major regret on the W212 Sedan was the one next to the driver's side firewall. I was ready to give up and the socket got stuck, %^&*(, regrouped after considering failure and managed it out. After that, it was a breeze to finish the other ones. I will never use a socket with a rubber into either the M272 or M276 engine (only ones I have done), magnetic all the way. I will have to try on my sister's W166 (also an M276 if I recall correctly) and see if the fender height makes it even worse (time of a step to work on?)


Is this the vacuum hose you are referring to? I did it like the video, but I never had to remove the hose

LEX HALL

I wished my plugs was this easy to access. I have 2016 E350 4matic and its not this easy.

chassis

Yes, this is the vacuum hose. There are slight differences in hose routings on W212/W213 and W166. I did not remove the vacuum hose, but it make access more difficult than if it was not there.

juanmor40

supposedly the W166 is more challenging, except for the oil dipstick and harness around it, I would say it is the same level of difficulty than the W212 RWD. I did sister's a few weeks ago

Notice the W166 requires more paneling to be removed, and I needed steps tool to reach more comfortably.

chassis

In addition to the fender height difference (step stool), the windshield seems farther forward on W166 than on W212, making the rearmost plugs a big more challenging to remove.