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I do most of the maintenance on my wife's 2016 GLC 300 and my e350 4matic. I like to think that I'm a good "shade tree mechanic"
But today a simple job as replacing the plugs in my wife's glc has me just twisted up.
I purchased the plugs from the dealer after showing them the VIN#. I check on the net to see if there is anything special and found that the plugs are "indexed" to face the injectors and a torque of 23 n meters.
Being a compulsive person I marked the the Electrode with a Sharpie to make sure the plugs faced the right direction. after installing the first plug and torquing it I was 90 degrees off from facing the injector.
I reinstalled the used plug with the same result. What am I missing??? Any help would be appreciated.
I do most of the maintenance on my wife's 2016 GLC 300 and my e350 4matic. I like to think that I'm a good "shade tree mechanic"
But today a simple job as replacing the plugs in my wife's glc has me just twisted up.
I purchased the plugs from the dealer after showing them the VIN#. I check on the net to see if there is anything special and found that the plugs are "indexed" to face the injectors and a torque of 23 n meters.
Being a compulsive person I marked the the Electrode with a Sharpie to make sure the plugs faced the right direction. after installing the first plug and torquing it I was 90 degrees off from facing the injector.
I reinstalled the used plug with the same result. What am I missing??? Any help would be appreciated.
Do you have any luck? At least the original plug has same result, that is good sign. Might help to search online for something similar for C-class W205.
The plugs are indexed by virtue of the torque specification. Doing a test on a used plug is meaningless because the crush washer, a single use item, has been used which means to say it has been crushed.
Iv'e just returned from my local Mercedes Dealer and the Service Manager was terrific, he went out of his way to help me. He printed the WIS of my 2016 glc 300 and reviewed it with me.
The correct plug is M.B. A 270 159 07 00 torqued to 23 n meters. NO indexing required.
I replaced spark plugs today @95,000km
14mm (or 9/16") pkug socket needed.
the replacing every 100,000 km is recommended by MB.
The last coil pack was tricky because of the smaller space but I got it out.
I blowed air before undo the plugs.
Be careful not to drop coil pack bolts into the engine bay.
new plugs. And 14mm socket Pulled plugs
Last edited by sn202020; Aug 17, 2020 at 03:37 AM.
Iv'e just returned from my local Mercedes Dealer and the Service Manager was terrific, he went out of his way to help me. He printed the WIS of my 2016 glc 300 and reviewed it with me.
The correct plug is M.B. A 270 159 07 00 torqued to 23 n meters. NO indexing required.
should have read my posts and saved yourself the trip lol
Let’s be clear. Indexing is required. This is accomplished by adhering to the installation torque spec.
When the torque spec is complied with, the electrode is oriented in the MB-designed orientation, which avoids piston erosion from improper electrode orientation.
Ok folks, this is a high precision, expensive vehicle. Stop Messing with it and trying to do stuff yourselves. 🛑 ✋ let the dealer do it properly.
It’s like $850, once every 4 years. Leave it alone
Ok folks, this is a high precision, expensive vehicle.
Stop Messing with it and trying to do stuff yourselves. 🛑 ✋ let the dealer do it properly.
It’s like $850, once every 4 years. Leave it alone
If you have done brake pads or engine oil replacement etc DIY,
probably you can do NGK spark plugs yourself with $50.
Save those difference $800 for next set of tires, or have nice dinners multiple times.
Originally Posted by chassis
Let’s be clear. Indexing is required. This is accomplished by adhering to the installation torque spec.
When the torque spec is complied with, the electrode is oriented in the MB-designed orientation, which avoids piston erosion from improper electrode orientation.
Repeat, indexing is required.
If you have done brake pads or engine oil replacement etc DIY,
probably you can do NGK spark plugs yourself with $50.
Save those difference $800 for next set of tires, or have nice dinners multiple times.
Furthermore, the article spells out the requirment for Mercedes plugs vs other manufacturers, such as NGK. The reason is in the article, I suggest you read and understand it.
There is a fairly wide tolerance on indexing. The electrode needs to be pointed as directly as possible to the fuel injector to avoid potential piston erosion over time.
Furthermore, the article spells out the requirment for Mercedes plugs vs other manufacturers, such as NGK. The reason is in the article, I suggest you read and understand it.
There is a fairly wide tolerance on indexing. The electrode needs to be pointed as directly as possible to the fuel injector to avoid potential piston erosion over time.
maybe not saving money in the long run, the engine might get damaged by all others DIY. This could set of a chain reaction and cause other problems. I would work on an old Chevy but not this vehicle
Furthermore, the article spells out the requirment for Mercedes plugs vs other manufacturers, such as NGK. The reason is in the article, I suggest you read and understand it.
There is a fairly wide tolerance on indexing. The electrode needs to be pointed as directly as possible to the fuel injector to avoid potential piston erosion over time.
The OEM plugs I pulled out are made by NGK with the model name SILZKFR8E7S stamped. MB OEM has the same stapmed model number of NGK. Thread start point
Which is exactly same model stamped on the new NGK. The threads starting point seems to be the same too. Only difference is OEM has the blue MB logo and NGK has NGK logo on the insulator.
I can say they are identical parts made by the same way at the same factory.
Last edited by sn202020; Aug 31, 2020 at 11:22 PM.
I know this is old, but want to ask did anyone mark the original plug installed by manufacturer before pulling it out and see were it was pointed? Im collecting SP replacement information as I dont trust dealers as some others do.
wondering why official work instruction dost call for indexing if its’s not on instruction do you really think tech will worry about?
Let’s be clear. Indexing is required. This is accomplished by adhering to the installation torque spec.
When the torque spec is complied with, the electrode is oriented in the MB-designed orientation, which avoids piston erosion from improper electrode orientation.
Repeat, indexing is required.
Near same results as the OP. I guess I'll revive this interesting thread. Just changed the plugs on my 2017 GLC300 Base Model. ALL 4 plugs from the factory were 70-80 degrees off centerline to the injector. I've seen several Benz documents (post #17 above) state must be within +/-45 degrees however I've never seen a document that specifically includes this engine and are dated 2014(?). If that document is truly a requirement this car wasn't correct from the factory, not even close. Replaced the plugs today with Benz plugs and they all indexed at about the same 70-80 degrees off centerline.
All very confusing assuming that Benz bulletin floating around stating +/- 45 degrees is a requirement.
Does anyone have any better insight into the confusion?
FYI: OEM plugs from the car (with Benz logo) are NGK SILZKFR8E7S
New OEM, 270 159 07 00 are NGK SILZKFR8H7S
Both have copper washers
Last edited by ArcticWhiteZ51; Jun 18, 2023 at 05:18 PM.
I guess I'll revive this interesting thread. Just changed the plugs on my 2017 GLC300 Base Model. ALL 4 plugs from the factory were 70-80 degrees off centerline to the injector. I've seen several Benz documents (post #17 above) state must be within +/-45 degrees however I've never seen a document that specifically includes this engine and are dated 2014(?). If that document is truly a requirement this car wasn't correct from the factory, not even close. Replaced the plugs today with Benz plugs and they all indexed at about the same 70-80 degrees off centerline.
All very confusing assuming that Benz bulletin floating around stating +/- 45 degrees is a requirement.
Does anyone have any better insight into the confusion?
FYI: OEM plugs from the car (with Benz logo) are NGK SILZKFR8E7S
New OEM, 270 159 07 00 are NGK SILZKFR8H7S
Both have copper washers
im attaching official WIS for plugs replacement.
i don't see any information on indexing.
and wouldn't expect tech at dealer ship will anything else but what is in the wis.
i follow this wis and changed plugs in my 2018 glc. No issues so far.
im attaching official WIS for plugs replacement.
i don't see any information on indexing.
and wouldn't expect tech at dealer ship will anything else but what is in the wis.
i follow this wis and changed plugs in my 2018 glc. No issues so far.
Yep, I have that doc. It just drives me crazy not being 100% sure about the installation. I wish someone could prove with a valid document listing whether or not this engine needs anything more than correct torque value with OEM plugs. If it needs specific angles it would be great to see this engine listed on such a document. I do know however that my plugs are very close to how they were installed from the factory.
Let’s be clear. Indexing is required. This is accomplished by adhering to the installation torque spec.
When the torque spec is complied with, the electrode is oriented in the MB-designed orientation, which avoids piston erosion from improper electrode orientation.
Repeat, indexing is required.
Are you stating 1) with OEM plugs and 2) proper torque that the plugs are indexed correctly? Is there documentation for this engine and the "correct angle"? Reason I say this is that my '17 GLC300 was 70-80 degrees off center for each plug. Seems to me the +/- 45 degree info flying around is irrelevant OR my engine wasn't assembled properly.
I found the same wis but year 2020 vs my 2017.
its in Russian but steps are the same as in 2017.
i highly doubt it needs anything else or MB doesn't tell techs to do it on purpose.
I just changed my plugs at 89,000 miles. I know it was overdue, so I was afraid the plugs might have seized or the boot on the coil might be stuck. But no such trouble. There's a good YouTube video that shows you everything. It's as easy as it looks. Just be careful not to drop a bolt...I dropped one and it added 10 minutes to the job, fishing it out. It took about 45 minutes total including getting the bolt out.
I finally broken down and bought a torque wrench...all these years of DIY just going by feel instead of knowing for sure how tight. It was a $100 and doing this job myself paid for it.
Like I stated, this was a very easy job. If you're a DIY guy, don't be intimidated. I'd say it's about the same difficulty as changing the oil. You can do it!
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glc300 Spark plug Replacement HELP
NO Indexing Required
