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Every spark plug I took out, the originals with MB Star logo on them, had the plug spark opening directed right up towards the injector. I don’t think this is coincidence to have all eight plugs the same way.
I try to get my new plugs close to same. I don’t see there is any harm doing that either.
It's not a coincidence, screw the plug in, torque to 23nm and like magic it is where it is supposed to be.
It's not a coincidence, screw the plug in, torque to 23nm and like magic it is where it is supposed to be.
Yes, I believe the Bosch spark plugs with MB logo are made to index correctly ON PURPOSE so people would bring their cars to MB shops for plug changes. Bosch is probably bound to make correctly indexing plugs only for MB with their contracts with them.
NGK as a Japanese company makes plugs correctly and they index fine as GTIBlack wrote in his post earlier. They are not bound with contract with MB. This is what I believe is going on with this all.
It is interesting too, that when I try to find spark plugs in two different MB dealer internet sites there is none to be found. Almost seems they do not sell spark plugs, you only get them if you have plugs changed by them.
Yes, I believe the Bosch spark plugs with MB logo are made to index correctly ON PURPOSE so people would bring their cars to MB shops for plug changes. Bosch is probably bound to make correctly indexing plugs only for MB with their contracts with them.
NGK as a Japanese company makes plugs correctly and they index fine as GTIBlack wrote in his post earlier. They are not bound with contract with MB. This is what I believe is going on with this all.
It is interesting too, that when I try to find spark plugs in two different MB dealer internet sites there is none to be found. Almost seems they do not sell spark plugs, you only get them if you have plugs changed by them.
So, continuing this "debate" and I think I found out, as I already guessed, the thread on the spark plug ends/starts in 90 degrees different position between plugs with MB logo and not.
The first picture below shows how the thread ends/starts right behind the electrode on the original BM plug while on the regular plug it ends/starts 90 degrees from behind the electrode. This gives exactly the result what happened with the plugs I bought from FCPeuro, i.e., the electrode opening stopped 90 degrees short from the TDC where the injector is.
The fix for this is to get plugs that are made correctly and I doubt you can buy those other than let MB dealer shop to do the plug change.
The second plug shows the plugs type is not the same. The original plug type starts "Z6S113..." while the type in plug from FCPeuro starts "ZR6S113...".
The plugs that FCPeuro and I know O'Reilly sells (and probably everybody else too) are indexed wrong. I bought 5 Bosch plugs from O'Reilly after I realized the plugs got damaged when trying to pre-crush the washers. I was actually doing stretching on the plugs that allowed for the correct indexing. I then used two very hard material washers and an all thread and flattened the washers and after that sanded them smooth both sides.
Just for anybody doing the plug change: If you buy the Bosch plugs that are sold to fit in the M278 engine (and they don't), get washers sanded down to 1.20mm - 1.25mm thickness so the plugs index correctly. If I do this job again, I'll get NGK plugs that were said to index correctly so installation is easy. Or get the MB-Logo plugs if they are available from the dealer.
maybe aftermarket think Merc torque values are insufficient and or possibly more likely NGK now decide the plug should sit at a different angle - don't forget its now 15 years since Merc thought they knew best - when the reality is DI in that implementation was wrong / dangerous for engine health....
what a load of rubbish - can't find 278 application in this at all, faulty list of cars for the W221 range at page 308
More confusion is that it appears turbo cars (at least for the M276.8XX engine) use one style of plug (6 point socket) and the non-turbo M276.9XX engine uses a different style (12 point socket). Plus, on the NA engines, you have FLEX and non-FLEX Fuel engines.
On the RockAuto.com website, here are the options for the M276 turbo and non-turbo engines:
An added thing to beware of is counterfeit spark plugs.
I replaced spark plugs in my 279 powered car 18 months or so ago. A month ago I got a misfire code. Pulled all the plugs out and looked much more closely at them than I did before install. Some lacked the iridium on the center electrode. Some lacked iridium on ground electrode. A few on both electrodes. Got to searching on intersnet. Sure enough; it is a thing. Chinesium counterfeit replacement NGK plugs that sure looked right (always when in a hurry) with packaging, colors on plugs ect turn out to be faux junk.
The plugs you purchase at the dealership are least likely to be counterfeit. Yes; Mercedes will happily sell them over the counter.
Just wanted to say I recently did plugs on my cls 550, it was a pain and I believe it would be next to impossible to mark the plug and see where the tip is sitting. Having said that, I tightened plugs appropriately, car runs perfect, absolutely no misfires so if you connect your scanner and check for possible misfires, then you will know if you have a problem. If no misfires, you're NOT going to damage the engine. They say that the possibility for engine damage isn't from improper indexing but from the missing that can occur from improper indexing. Therefore, very simply check for misfiring with your scanner lol. If no misfires, all is good. If you have a cylinder misfiring, maybe remove the plug and retorque
@Billydv1 having done plugs five times on three cars....NO WAY anyone can visualize 4-7-8 on a GLS or 8 on an E63. Not with out taking the engine out of the car. I use the real MB plug socket too...impossible to see...You and I are 100% on the same page
@Billydv1 having done plugs five times on three cars....NO WAY anyone can visualize 4-7-8 on a GLS or 8 on an E63. Not with out taking the engine out of the car. I use the real MB plug socket too...impossible to see...You and I are 100% on the same page
Little confused here.
If you can get to the spark plug and remove it, you can mark the tool where the electrode opening on the plug is supposed to be, i.e., towards the injector. Then, when installing plug you set the electrode opening to the mark and after torquing to the set value you can see where the marking on the tool stops.
Lol
not exactly
The plugs are deeply recessed in the sides of the motor on an m278, not talking about the earlier 8 cylinder on s classes and the like on 2011 or earlier. Im talking 2012 or later. The plugs are very difficult to get to, removing the spark plug wires is next to impossible if grease wasn't applied. Next problem you run into is the rubber boot breaks off on the plug and you CANNOT get the socket on it. I had to destroy several screwdrivers bending them into chisel tools to cut away the boots to actually be able to remove the plugs. You could certainly mark the plug but even with a mirror, you're never going to see the mark.
Sorry to say but this indexing nonsense is just that. The plug DOES have to be tightened correctly, if it is and the car doesn't have misfire as is easily verifiable with on board monitor with any decent scan tool, you are good
Lol
not exactly
The plugs are deeply recessed in the sides of the motor on an m278, not talking about the earlier 8 cylinder on s classes and the like on 2011 or earlier. Im talking 2012 or later. The plugs are very difficult to get to, removing the spark plug wires is next to impossible if grease wasn't applied. Next problem you run into is the rubber boot breaks off on the plug and you CANNOT get the socket on it. I had to destroy several screwdrivers bending them into chisel tools to cut away the boots to actually be able to remove the plugs. You could certainly mark the plug but even with a mirror, you're never going to see the mark.
Sorry to say but this indexing nonsense is just that. The plug DOES have to be tightened correctly, if it is and the car doesn't have misfire as is easily verifiable with on board monitor with any decent scan tool, you are good
Ok,
you are not understanding the “marking the tool” part.
I have exactly the m278 that I changed and successfully indexed the spark plugs for. You need to have correct tools for the job.
I had the plug wrench that came with the FCP kit. I then taped a short extension to it.
When I removed the original plugs I marked the extension on the plug wrench and positioned this mark pointing straight up (or as close to as possible) and then turned the plug out of thread making sure it is all out before removing the tool with the plug from the deep hole. I could then see how well the original plugs were indexed and they were all very well at mark.
With new plugs I positioned the electrode opening at the mark on the tool and torqued the plugs to 23Nm as is specified in the plug package. All plugs stopped about 90 degrees short from where they need to turn. I was able to easily see the mark on my tool and after sanding the plug washers down to about 1.25mm thickness they all turned the missing 90 degrees and I got them correctly indexed.
As I mentioned in my earlier post the need for indexing probably warrants a new thread itself but as indexing for sure does not cause any harm why not do it then?
In my post #53 is two pictures of the MB and general plugs. The upper one shows how the thread in MB plug ends right behind the electrode while on the general plug it ends 90 degrees short. This is why indexing goes wrong with general plugs.
The other picture shows the difference “R” in the part number stamped on the plug. Other than this the part numbers are the same.
And not having misfires does not tell the whole story. A cylinder can run without misfire but improperly indexed spark plug might cause some incomplete fuel burn that can hurt your gas mileage.
If it makes people feel better to think that they're actually able to visualize something more power to them..... that said if anybody's under the delusion that a dealership or even a tuner is going to go to that length they are confused
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