C-Class (W203) 2001-2007, C160, C180, C200, C220, C230, C240, C270, C280, C300, C320, C230K, C350, Coupe

Spark Plug Change

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Old Jan 16, 2020 | 01:29 PM
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08 E350 4MATIC's Avatar
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2004 C240
Spark Plug Change

Hey:
I am getting ready to change the spark plugs on my 2004 Mercedes C240.

Is a 10in total spark plug socket and extension good enough to get the plugs in and out?

Thanks
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Old Jan 17, 2020 | 06:52 AM
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2005 C240 2011 R350
Honest I dont remember... but one of the toughest parts is getting the boot off!

Also.. be very careful. Ease them out slowly... start with quarter turn out then in.. then half turn out and in a quarter etc There is lots of buildup and if you try to do it all at once or with a power driver you risk stripping the aluminium threads on the heads. for the new ones I used a bit of nickel based (the silver coloured permatex stuff) antiseize compound but the plugs should already have an antiseize coating.

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Old Jan 17, 2020 | 08:25 AM
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2004 C240
Thank you
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Old Jan 17, 2020 | 02:25 PM
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Mercedes-Benz S430, S500, S600, and E320 CDI
Getting the boot off is easy if you have this tool.

https://mercedessource.com/store/m11...t-removal-tool

They can also be had on eBay. IIRC, I bought mine on there before I learned that Kent sells 'em, too. Avoid "made in China", but Taiwan's upped their quality game over the years, so they're OK.

As for the spark plugs themselves, yeah, a 10" extension is what I use. Mine came off pretty easily. Yours may not, so yes, be a little careful at first. That Permatex anti-seize compound is great stuff, BTW. And be careful not to over-torque your new spark plugs when you put 'em on! I think the torque spec is 18 lb-ft.

Last edited by cowboyt; Jan 17, 2020 at 02:27 PM.
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Old Jan 17, 2020 | 02:51 PM
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2004 C240
I have the tool coming in the mail for the boot.

I was worried that 10" would be to long to get the plugs out that are closest to the firewall?

Thanks
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Old Jan 29, 2020 | 08:35 AM
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What do you guys think the gap should be on the plugs?

I read that the dealer does .044 but that using .035 should work because it expands.

Thanks
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Old Jan 29, 2020 | 09:06 AM
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Most plugs are pregapped be carefull if you want to adjust the gap . The point is very fine. Not your grandfather's spark plug!
some articles

https://ngksparkplugs.com/en/resourc...ut-spark-plugs

https://www.boschsparkplugs.net/lear...i-gap-my-plugs
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