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Hi,
I have changed my spark plugs on my m276 without removing the top plenum thanks to the attached pdf.
It's from the slk forum so kudos to the author.
Took me 30 minutes all around.
My car idles so much better.
This diy requires removing the ecu and i do recommend disconnecting the battery.
I hope it helps as removing the plenum is more involving.
I been looking into this since my 2013 should hit 60k early next year. How would you classify the spark plugs at 60k miles? I feel tempted to delay until 80 or 90k since i've never changed spark plugs before 100k I think Mercedes is just being overly cautious due to DI being fairly new technology.
Been looking for a guide for My ML350 with the same engine without success until now. Should be even easier since i have a ton of free space . Thanks buddy
This is indeed a most helpful DIY on a procedure that is hard to find for the M276 engine, so I add my kudos and thank you to the author. However, it has at least one inaccuracy. It states that the clamp holding the air filter housing tube to the resonance intake manifold is a one-time use part and should not be undone. That is not true. That clamp is what is called a “Click-R”, or just “Click”, clamp, which, in fact, is designed to be reused multiple times. The only caveat is that you need to have the proper clamp tool to open and close it. There are several of these tools on the market and several YouTube videos on these types of clamps and how to open and close them, which is very easy. I use the tool on this link (
) and am very happy with it. Removing the air filter housing makes this job much easier. Of course, it helps for changing the engine air filter as well, which is why that type of clamp is there in the first place. Cheers,
By the way, what is the MB-recommended torque for the spark plugs on the M276 engine?
23 nm, same as the 272. It's not very much, don't get carried away. The 276/278 plugs are indexed from factory so torque matters, too much or too little and you twist the plug away from the injector. They are also one-time use because of this, once you've installed and tightened them, if you remove them they are trash, the next time they go in they won't land in the same spot as the gasket has already been squished.
23 nm, same as the 272. It's not very much, don't get carried away. The 276/278 plugs are indexed from factory so torque matters, too much or too little and you twist the plug away from the injector. They are also one-time use because of this, once you've installed and tightened them, if you remove them they are trash, the next time they go in they won't land in the same spot as the gasket has already been squished.
I used the guide for the cheater method to do my plugs and it worked pretty well.
I’m only at 45k miles but I bought the car used and noticed some hesitation while accelerating.
a couple quick notes... the passenger side is very simple and straightforward. Pretty easy access one the air filter box is out of the way. By far the most difficult part was removing the connectors on the coils.
on the driver side, everything is much harder. The #6 coil is really quite the pain to remove. I used a shoestring looped under the shoulder of the boot to remove the coils. I saw the the instructions used a homemade puller, but with the space allowed, I couldn’t fathom wrapping anything around the boot. Just sticking the shoestring under the outside shoulder where it comes out of the spark plug hole, and pulling up on that worked well.
definitely a very doable job if you want to save some money. My local shop quoted $300 for doing it with parts I already bought.
one interesting find was the condition of my plugs. 1-3 were covered in deposits while 4-6 looked pretty normal. Not sure what is / was causing it.
PCV flow is biased, more goes into one side of the engine than the other. That one plug on the bottom does look pretty bad for 45k miles, most of the ones I change around that mileage don't look worn at all or have any noticeable deposits.
I hate to cause worry but I'd lift the plenum and check the intake valves. You may have inherited a car that was not driven enough and has deposits on the intake valves causing poor airflow to the chambers under certain conditions. Easy enough to check, but the remedy will be walnut blasting the valves which is not as simple.
I’ve wondered if there was any buildup, and am definitely a little concerned about the state of the first couple plugs. It would make sense if there was carbon buildup on the valve and the mix is running rich due to restricted airflow in that cylinder.
I also suspect that the dealership where I purchased the car was putting regular fuel in it instead of using the correct octane rating, and probably conventional oil as well.
I will now have to prep to remove the intake plenum in the near future. I think I’ll need new seals for that job from what I’ve seen. But if I’m doing that then I may as well switch out the crankcase breather valve at the same time. Had a Volvo that taught me the importance of a well functioning pcv
You can re-use the manifold seals, I wouldn't be too concerned if you're removing it to inspect. In a GLK it's not too bad to get out either, couple electrical connections, one small vacuum line that goes to the vac pump on the rear of the engine (impossible to unplug the hose usually, I remove the small t-25 bolt at the pump), and the plenum comes up pretty easily. The seals will stick in the plenum, take them out and put them back on the lower part for re-install, they have a notch and have to sit down flat or they can pinch, but are usually perfectly fine to re-use as long as you put them on right.
This set of instructions is amazing! I have used it, and it was really accurate.
You might want yo update if interested with the spark plugs torque 23 nm,
Other than that flawless, thanks for taking your time to put that together, really helps other MB owners like me!
What plugs are people using when replacing them OEM spark plugs? I bought some BSH ZR6SII3320 Bosch plugs and they are pre gapped (@Do Not Gap, Gap is Preset@) The package shows that the gap is .028. Let me know before I put these suckers in. Thanks!
And that document is tremendous, thanks for sharing! I did watch a youtube where the guy tuck the plenum off and it did not look like a fun time.
Great thread. Here is a recently posted instruction set and videos for the M276 3.5L NA engine spark plug replacement. This is done on an E350 by Senior Leigh. He is a poster here, his userid is all numbers on this site and he usually posts in the "Technical" section.
So is it safe to assume this procedure should work on any m276 engine in any chassis, say a w212?
@nightspd Generally yes. There are many M276 spark plug threads on this site, including W212. Senior Leigh's video is done on a W212. My W166 is essentially the same, except for platform-specific differences on the driver's/left side of the engine related to ECU mounting and vacuum line routing.
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