Guidance for Spark Plug replacementr (M276) [2019 E450]

[tivoliman]

The parts department tells me that the E450 has 6 spark plus (different from my M113.940 which had 2 plugs per cylinder).

How often should I replace the coils? Each plug change? (50,000 miles)

What all must be removed to access the plugs?

Many thanks

[engatwork]

You just have to open hood and look at what all has to be removed to get to them.

Do not replace coils until they start to fail which, in my experience, has been after 180k miles in MB.

[tivoliman]

thanks for the guidance. sounds "easy"

[engatwork]

I don't remember specifics but it is really straight forward. Hardest part to me is always getting the coils of thevplugs.

[porkface]

better to have the dealer do this. this way you have plausible deniability-

file:///C:/Users/Auto%20Repair/Downloads/M276%20Spark%20Plug%20Indexing.pdf

[tivoliman]

Seems the file you referenced is on your local drive ... C:

Thanks for your help.

[porkface]

sorry, this works-

https://techtips.alleuro.com/wp-content/uploads/2020/02/mercedes-spark-plug-index.pdf

[porkface]

i have pictures of melted pistons on that motor due to not indexing the plugs. can't upload them here.

[vince]

As the bulletin states, the indexing is achieved by using the correct plugs and applying the correct torque of 23nM. I've done them on my 2014 ML350 twice (60K interval) and now have 135K on the car with no problems. As for access, the WIS says to remove the upper section of the intake manifold. On the ML that is really difficult to do due to the shape of the firewall (there is a removable section that is a royal PITA to remove). The sedans are much easier. I do not remove the upper intake. It is tight reaching/releasing the coil wire connectors under the intake but doable. Drivers side is the more difficult. The passenger side is easy after removing the air filter housing. Buy the plugs from the dealer. Here is a pdf that I found helpful - for SLK but it worked for me.

https://www.slkworld.com/threads/changing-spark-plugs-or-ignition-coils-on-the-r172-3-5l-v6-m276-engine-version-2.578791/