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Hey guys, never saw this actually posted anywhere on the forum so figured id add the document here for reference for current and future members. Thought the more articles we have on here and more knowledge we spread, the better decisions we can all make.
Hence the call for OEM plugs and being very specific when torquing them. Plug has to be a specific length, and when tightened to tq spec, has to be facing the direct injector in the cylinder chamber up 45 degrees either way from it.
Tech service bulletin from Mercedes AMG
Just providing information that the techs at MB have that us customers should have aswell. The better we are all informed, the better decisions we can all make and move this platform forward Knowledge is power!
Just providing information that the techs at MB have that us customers should have aswell. The better we are all informed, the better decisions we can all make and move this platform forward Knowledge is power!
FYI - here’s the PDF from MB about M157 spark plugs indexing requirement since these are direct injection motors and the open side of the electrode needs to be up to max 45 degrees facing the injector (per the doc..not me, just passing along) to avoid possible cylinder damage and converter damage.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
An old thread, but notice the date of the document publication -- 2014. Also, attacking NGK seems not only unfair, but suspicious in the motivation of the author (John Dahlquist). NGK plugs are used in many Mercedes engines as original, factory plugs. The author also does not make a distinction between turbo and non-turbo engines, or stratified versus homogeneous combustion. If indexing is required, it doesn't matter what brand (NGK, Bosch, Autolite, etc.) is used, if done wrong, damage may occur.
I have a US M276.8XX (turbo) engine which technically should not need indexing because it uses homogeneous combustion. However, I use NGK OE plugs (96427) and index them anyway because I figure it can't hurt. Plus, with the NGK plugs, they index perfectly at 23 Nm torque.
So I just went through this on my 2019 GLE 63s coupe. 56,000 miles. Original plugs and coils. Checked every single plug on the way out. Every single on of them on the 1,2,3,4 bank the strap was pointing directly towards the firewall. Every new plug (bosch identical to factory) went in and pointed at the exact same direction directly towards the firewall. The 5,6,7,8 bank all were pointing directly forward at the radiator on the way out and all of the new ones went in exactly the same pointing towards the radiator. It worked for 56,000 miles from the factory so I didn't mess with it. It directly contradicts the bulletin above. The plugs that came out were original mercedes in the engine from the factory.
I really think this has more to do with the wrong plug and electrode than where the strap is pointing. But that's my opinion.
So I just went through this on my 2019 GLE 63s coupe. 56,000 miles. Original plugs and coils. Checked every single plug on the way out. Every single on of them on the 1,2,3,4 bank the strap was pointing directly towards the firewall. Every new plug (bosch identical to factory) went in and pointed at the exact same direction directly towards the firewall. The 5,6,7,8 bank all were pointing directly forward at the radiator on the way out and all of the new ones went in exactly the same pointing towards the radiator. It worked for 56,000 miles from the factory so I didn't mess with it. It directly contradicts the bulletin above. The plugs that came out were original mercedes in the engine from the factory.
I really think this has more to do with the wrong plug and electrode than where the strap is pointing. But that's my opinion.
Buying OEM plugs have its advantages such as being pre-indexed.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
Knowledge is power!
