SL/R231: Spark plugs.
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2015 SL400; 2019 X5M40i
Don't know what MB recommends but running high quality non-leaded gas and regular oil changes, plugs should easily last 50k miles. My wife's RX just turned over 100k miles with the original plugs. Runs like new.
I may change my SL plugs at 50k miles.
I may change my SL plugs at 50k miles.
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ThatsMyDawg (09-17-2024)
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Just a SWAG... but depending on the material used, perhaps leaving them in too long makes them harder to get out because of corrosion???
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2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
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What, if any downside is there to not changing plugs per recommended maintenance interval?
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I'm led to believe that the 4 years is because the plugs can gall and get stuck, so I suppose you could just take them out at 4 years and put them back in again. My take though is that if you've gone to the trouble of taking them out then why not put new plugs in? A set of genuine plugs from mercedes is not much more than a full tank of fuel (UK prices), so why wouldn't you?
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2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
I've used iridium plugs for decades and generally they are good for 100,000 miles. The steel ground strap will erode long before the iridium electrode. When I have replaced my plugs on my C350 (M276 NA) at 60,000 and 124,000 miles, they looked virtually new with no noticeable change in gap. (Changing the plugs on the M276 NA 3.5 liter engine is a pain-in-the-*** since you have to remove the intake manifold.) If I had to choose between replacing the spark plugs (assuming the engine is running fine) and doing a transmission service, I would opt for the transmission service.
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2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
M276.8XX SL400
M276.8XX SL400 Closeup
M276.9XX C350
M276.9XX C350 Closeup
V6S113320
Z6S113320
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I know the C350 plug looks shorter, but they are actually the same length (close). I had removed the crush washer from the SL400 plug, but the washer is the same thickness as the C350 plug.
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I recommend using genuine Mercedes plugs, however I use NGK 96427 plugs, which are also OE specific to Mercedes GDI engines.
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There is a YouTube video by ExoticCarDIY that gives good instructions on how to index the plugs.
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Spent some time watching videos and researching plugs. Seems NGK is or was the supplier of the Mercedes branded OEM plug. Is this correct? Is the Bosch plug equivalent so that it will index correctly?
After watching several videos. I don't think I want to tackle this job especially if the removal of the intake manifold is required. Getting some estimates from reputable shops now.
Jetta, do you have an Indy to recommend? I found one in Martinsburg, WV. I really don't want to head down 270. Will check the dealer in Hagerstown and Sun Motors up 81. They serviced my tranny and did a great job.
Added:
Sun just got back to me. Plug replacement would be $500. They don't recommend replacing the coil packs unless there is a problem.
After watching several videos. I don't think I want to tackle this job especially if the removal of the intake manifold is required. Getting some estimates from reputable shops now.
Jetta, do you have an Indy to recommend? I found one in Martinsburg, WV. I really don't want to head down 270. Will check the dealer in Hagerstown and Sun Motors up 81. They serviced my tranny and did a great job.
Added:
Sun just got back to me. Plug replacement would be $500. They don't recommend replacing the coil packs unless there is a problem.
Last edited by rmorin49; 09-19-2024 at 05:34 PM.
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2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Spent some time watching videos and researching plugs. Seems NGK is or was the supplier of the Mercedes branded OEM plug. Is this correct? Is the Bosch plug equivalent so that it will index correctly?
After watching several videos. I don't think I want to tackle this job especially if the removal of the intake manifold is required. Getting some estimates from reputable shops now.
Jetta, do you have an Indy to recommend? I found one in Martinsburg, WV. I really don't want to head down 270. Will check the dealer in Hagerstown and Sun Motors up 81. They serviced my tranny and did a great job.
Added:
Sun just got back to me. Plug replacement would be $500. They don't recommend replacing the coil packs unless there is a problem.
After watching several videos. I don't think I want to tackle this job especially if the removal of the intake manifold is required. Getting some estimates from reputable shops now.
Jetta, do you have an Indy to recommend? I found one in Martinsburg, WV. I really don't want to head down 270. Will check the dealer in Hagerstown and Sun Motors up 81. They serviced my tranny and did a great job.
Added:
Sun just got back to me. Plug replacement would be $500. They don't recommend replacing the coil packs unless there is a problem.
I installed the NGK plugs because they are identified as OE parts by FCP. I actually got mine from RockAuto. I had also tried Bosch plugs from FCP and they would not index correctly, so I returned them. The NGK plugs indexed nicely within the +/- 45° range. They actually were probably within +/- 25° to 30° to the fuel injectors.
It looks like Genuine Mercedes plugs are made in Japan, as well. If you are uncertain about the NGKs, the Genuine plugs are only a few dollars more than the NGKs.
Last edited by JettaRed; 09-19-2024 at 06:23 PM.
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Changing plugs on your car is relatively easy. No need to remove the intake manifold, just the air intake and filters, which come off very easily. (Changing the plugs on the 3.5 liter M276 is a different story!) Have you tried the dealership? They may let you provide your own plugs. Remember, the parts department and service department are separate entities. I have not used any independent shops since I do just about all of my own work.
I installed the NGK plugs because they are identified as OE parts by FCP. I actually got mine from RockAuto. I had also tried Bosch plugs from FCP and they would not index correctly, so I returned them. The NGK plugs indexed nicely within the +/- 45° range. They actually were probably within +/- 25° to 30° to the fuel injectors.
It looks like Genuine Mercedes plugs are made in Japan, as well. If you are uncertain about the NGKs, the Genuine plugs are only a few dollars more than the NGKs.
I installed the NGK plugs because they are identified as OE parts by FCP. I actually got mine from RockAuto. I had also tried Bosch plugs from FCP and they would not index correctly, so I returned them. The NGK plugs indexed nicely within the +/- 45° range. They actually were probably within +/- 25° to 30° to the fuel injectors.
It looks like Genuine Mercedes plugs are made in Japan, as well. If you are uncertain about the NGKs, the Genuine plugs are only a few dollars more than the NGKs.
Is this the correct NGK plug, same as the MB branded one?
https://www.fcpeuro.com/products/mercedes-spark-plug-kit-ngk-0041597203
Last edited by rmorin49; 09-19-2024 at 08:17 PM.
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Well, I may give it a try after all. I recently replaced both engine air filters and was pleasantly surprised at how easy it was.
Is this the correct NGK plug, same as the MB branded one?
https://www.fcpeuro.com/products/mer...ngk-0041597203
Is this the correct NGK plug, same as the MB branded one?
https://www.fcpeuro.com/products/mer...ngk-0041597203
Last edited by JettaRed; 09-19-2024 at 10:06 PM.
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Removing the ignition coils can be hard, but there is a part (arrow) that helps you grab onto the boot and pull it out. The coil may separate from the boot when you try to remove it, but that is ok.
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Another interesting video.