Just like with my other posts, I am going to lay out some instructions on how to completed a spark plug service on a 2016 G63, but this process would apply really to any Mercedes with the same block. Since the motor in my vehicle is an M157, this would retroactively apply direct to an E63, S63 etc...
Please be forewarned. This is an easy job but you need to be very careful, especially when you get to the driver's side. The driver's side plugs are exponentially more difficult than the passenger side, particularly on the two cylinders closest to the firewall. There are a couple technical procedures you need to be mindful of as you install/re-install the coil packs and plugs. A dealer quoted me $1500 for the change, which is ridiculous considering the parts cost $87 and the job took two hours to complete. You be the judge on if this is worth it, but the process is simple if you are mechanically inclined.
This service was completed at 5/41k and the most noticeable difference I felt was a smoother idle. There are times where I'd get some slight hesitation upon acceleration and a rougher than normal idle, so it's money well spent in my opinion. I believe the service manual calls for 5/60k for this service, but it is what it is. If you don't have any idling or misfires issues, I wouldn't bother with this service unless you care about preventative maintenance.
Expected Time: Two hours if you have the right tools and take your time
Difficulty: 6 out of 10. This is a very easy job but you need to be careful as you complete the procedure, especially on the driver's side. If you've changed plugs before or have worked on the M157 in the past, I would rate this more like a 3 or 4 out of 10.
Parts: You will need a set of plugs and a 12 point, 14mm socket. FCP euro carries a complete kit here and will cost $87 https://www.fcpeuro.com/products/mer...t-bosch-517013. The plugs in this kit come pre-gapped, which makes life easier.
Tools: You will need a socket set with various extensions and some type of U or swivel joint extension to access the plugs on the driver side near the firewall. Outside of the 12 point spark plug socket, most important socket will be an 8mm torx socket to remove the coil pack torx bolts.
The Procedure along with some tips
Warm up the engine. This procedure has steps that are 10x easier when the engine is warm, specifically removing the coil pack boots from the spark plugs. I warmed mine up to about 100 degrees on the oil temp side, then shut the motor down.
Remove the engine cover and the air boxes. The covers pop right out and are held in by retaining clips. The air boxes are held in by two screw clamps on the inlet/outside of the air box, and two retainers that pop onto rubber mounts underneath. Once you unscrew the retainers, the air boxes pop out. After the air boxes is moved out of the way, there is a rubber/foam-ish cover that covers the fuel rail and plugs. Pull that out. I would advise you remove one side at a time and I personally started with the passenger side because it's easier. Complete all four plugs, then go to the other side.
3. Locate the coil packs. Each pack will have two 8mm torx socket bolts holding them in place. remove both bolts, then the coil pack and boot will hang freely. Make a mental note in your mind how much force it took to break loose, which isn't a lot. Pro Tip: Be careful removing these, and use a proper set of high quality sockets. These bolts are made of aluminum, so they strip easily. I ended up stripping one and it was a living hell I don't want to live in again. As you can see in the picture below, the area around the bolts is such a tight fit that most conventional removal methods are difficult to complete. I was oddly fortunate enough where my stripped bolt was on the most forward coil pack closest to the radiator. The closer you are to the firewall, the more ****ed you are so be careful.
4. Carefully remove the coil pack boot. These are the rubber tube looking things that go from your coil pack down into the block where your spark plug is located. You need to be careful as you pull the boots because you can rip these if you're not careful. Fortunately, these are cheap to replace if you do tear one. Pro Tip: I found great success reaching as far down as possible, grabbing the boot, then slowly applying gradually increasing upward pressure. Once you feel the boot start to release, ease it out. Many people break these boots. I didn't break a single one, so as long as you are careful, you'll be ok. Once the boot is out, your work area will look like the images below. The opening in the first picture is where your spark plug is located.
5. Grab your 12 point socket and attach it onto an extension and a ratchet. Drop it into the hole until the spark plug seats into plug and back the plug out. There are quite a few threads so you'll need to make a few turns before it releases. Please note that when you pull your ratchet out, slowly pull the entire unit to prevent the extension un-attaching from the socket. It's not a big deal but it's a headache because you're going to be sticking the male end of your extension into a hole you cannot see into trying to mate it with the female end of the 12 point socket. The idea is to get everything out in one piece. Pro Tip: To save yourself time, detach the ratchet and spin the plug out by hand using your extension as seen here: https://i.imgur.com/tgoislC.mp4. This goes the same in reverse when you're re-threading the plug in. The engine compartment is tight and you can use all the room you can get.
6. Inspect your plugs. Make sure you don't see anything wrong that could be indicative of other problems upstream such as a rusted prong or the plug covered in ash. As a comparison, here is one of my used plugs vs a new one. The old one was still in great shape, but some of these plugs were in worse shape.
7. Install your new plugs. The procedure is the same as when you pulled the plug and coil pack out but in reverse. The Mercedes spec calls for a 23nm torque of the plugs into the head, which converts to 17 foot pounds. Make sure your torque wrench is properly dialed in because the threads on these plugs are tapped to ensure the orientation is properly set when it's in the combustion chamber.
8. Push your coil pack unit back into the hole where the spark plug is. You'll know the depth is correct when your coil pack aligns with the block so you can screw your bolts back in. Pro Tip: Those two coil pack bolts are aluminum, and you always need to be careful with aluminum bolts. Per my instructions above, use the mental note you took when the bolts were broke loose to estimate how much to torque down. I would tighten these to a hair past when you first feel resistance.
9) On the drivers side the procedure is the same except you'll need acrobatics and some real patience to reach a few of the plugs due to the brake booster and the lines that run on the side.
10. The three pictures below show the position of the socket to access cylinder 2, 3 and 4 on the drivers side, in that order. Cylinder 4 is by far the most difficult and it took some creativity to get that plug out using a u joint extension.
11. Repeat the procedure to torque your plugs, reinstall your air box and engine covers and you're done.
Is there a recommended torque setting for the 8mm hex bolts on the coil packs? I know the spark plugs are pre-gapped and require 23nm. Thanks for the write up I’m doing my 2015 next week.
Is there a recommended torque setting for the 8mm hex bolts on the coil packs? I know the spark plugs are pre-gapped and require 23nm. Thanks for the write up I’m doing my 2015 next week.
In the absence of a shop manual having torque specs for every fastener, you can refer to engineering standards such as the attached metric bolt torque table that ensures bolts aren't over-tightened.
Just like with my other posts, I am going to lay out some instructions on how to completed a spark plug service on a 2016 G63, but this process would apply really to any Mercedes with the same block. Since the motor in my vehicle is an M157, this would retroactively apply direct to an E63, S63 etc...
Please be forewarned. This is an easy job but you need to be very careful, especially when you get to the driver's side. The driver's side plugs are exponentially more difficult than the passenger side, particularly on the two cylinders closest to the firewall. There are a couple technical procedures you need to be mindful of as you install/re-install the coil packs and plugs. A dealer quoted me $1500 for the change, which is ridiculous considering the parts cost $87 and the job took two hours to complete. You be the judge on if this is worth it, but the process is simple if you are mechanically inclined.
This service was completed at 5/41k and the most noticeable difference I felt was a smoother idle. There are times where I'd get some slight hesitation upon acceleration and a rougher than normal idle, so it's money well spent in my opinion. I believe the service manual calls for 5/60k for this service, but it is what it is. If you don't have any idling or misfires issues, I wouldn't bother with this service unless you care about preventative maintenance.
Expected Time: Two hours if you have the right tools and take your time
Difficulty: 6 out of 10. This is a very easy job but you need to be careful as you complete the procedure, especially on the driver's side. If you've changed plugs before or have worked on the M157 in the past, I would rate this more like a 3 or 4 out of 10.
Parts: You will need a set of plugs and a 12 point, 14mm socket. FCP euro carries a complete kit here and will cost $87 https://www.fcpeuro.com/products/mer...t-bosch-517013. The plugs in this kit come pre-gapped, which makes life easier.
Tools: You will need a socket set with various extensions and some type of U or swivel joint extension to access the plugs on the driver side near the firewall. Outside of the 12 point spark plug socket, most important socket will be an 8mm torx socket to remove the coil pack torx bolts.
The Procedure along with some tips
Warm up the engine. This procedure has steps that are 10x easier when the engine is warm, specifically removing the coil pack boots from the spark plugs. I warmed mine up to about 100 degrees on the oil temp side, then shut the motor down.
Remove the engine cover and the air boxes. The covers pop right out and are held in by retaining clips. The air boxes are held in by two screw clamps on the inlet/outside of the air box, and two retainers that pop onto rubber mounts underneath. Once you unscrew the retainers, the air boxes pop out. After the air boxes is moved out of the way, there is a rubber/foam-ish cover that covers the fuel rail and plugs. Pull that out. I would advise you remove one side at a time and I personally started with the passenger side because it's easier. Complete all four plugs, then go to the other side.
3. Locate the coil packs. Each pack will have two 8mm torx socket bolts holding them in place. remove both bolts, then the coil pack and boot will hang freely. Make a mental note in your mind how much force it took to break loose, which isn't a lot. Pro Tip: Be careful removing these, and use a proper set of high quality sockets. These bolts are made of aluminum, so they strip easily. I ended up stripping one and it was a living hell I don't want to live in again. As you can see in the picture below, the area around the bolts is such a tight fit that most conventional removal methods are difficult to complete. I was oddly fortunate enough where my stripped bolt was on the most forward coil pack closest to the radiator. The closer you are to the firewall, the more ****ed you are so be careful.
4. Carefully remove the coil pack boot. These are the rubber tube looking things that go from your coil pack down into the block where your spark plug is located. You need to be careful as you pull the boots because you can rip these if you're not careful. Fortunately, these are cheap to replace if you do tear one. Pro Tip: I found great success reaching as far down as possible, grabbing the boot, then slowly applying gradually increasing upward pressure. Once you feel the boot start to release, ease it out. Many people break these boots. I didn't break a single one, so as long as you are careful, you'll be ok. Once the boot is out, your work area will look like the images below. The opening in the first picture is where your spark plug is located.
5. Grab your 12 point socket and attach it onto an extension and a ratchet. Drop it into the hole until the spark plug seats into plug and back the plug out. There are quite a few threads so you'll need to make a few turns before it releases. Please note that when you pull your ratchet out, slowly pull the entire unit to prevent the extension un-attaching from the socket. It's not a big deal but it's a headache because you're going to be sticking the male end of your extension into a hole you cannot see into trying to mate it with the female end of the 12 point socket. The idea is to get everything out in one piece. Pro Tip: To save yourself time, detach the ratchet and spin the plug out by hand using your extension as seen here: https://i.imgur.com/tgoislC.mp4. This goes the same in reverse when you're re-threading the plug in. The engine compartment is tight and you can use all the room you can get.
6. Inspect your plugs. Make sure you don't see anything wrong that could be indicative of other problems upstream such as a rusted prong or the plug covered in ash. As a comparison, here is one of my used plugs vs a new one. The old one was still in great shape, but some of these plugs were in worse shape.
7. Install your new plugs. The procedure is the same as when you pulled the plug and coil pack out but in reverse. The Mercedes spec calls for a 23nm torque of the plugs into the head, which converts to 17 foot pounds. Make sure your torque wrench is properly dialed in because the threads on these plugs are tapped to ensure the orientation is properly set when it's in the combustion chamber.
8. Push your coil pack unit back into the hole where the spark plug is. You'll know the depth is correct when your coil pack aligns with the block so you can screw your bolts back in. Pro Tip: Those two coil pack bolts are aluminum, and you always need to be careful with aluminum bolts. Per my instructions above, use the mental note you took when the bolts were broke loose to estimate how much to torque down. I would tighten these to a hair past when you first feel resistance.
9) On the drivers side the procedure is the same except you'll need acrobatics and some real patience to reach a few of the plugs due to the brake booster and the lines that run on the side.
10. The three pictures below show the position of the socket to access cylinder 2, 3 and 4 on the drivers side, in that order. Cylinder 4 is by far the most difficult and it took some creativity to get that plug out using a u joint extension.
11. Repeat the procedure to torque your plugs, reinstall your air box and engine covers and you're done.
Thanks. This is very good.
I notice no mention was given to marking the spark plugs to confirm indexing relative to the injector, within MB spec. What is your opinion about this?
I notice no mention was given to marking the spark plugs to confirm indexing relative to the injector, within MB spec. What is your opinion about this?
that's why the torque spec is there. That controls the index.
I struggled with this job using the 14mm 12 point socket from FCP Euro. I did 6 cylinders and gave up bc when i got to cylinder #8 I couldn't quite get the spark plug out as my swivel extension kept popping out. So i went to KC Tools and bought the Hazet 4766-3, this is the one that the Benz Techs use and can be found w the 3-pointed star emblem at a higher price point (but still made by Hazet). With the Hazet, the spark plug in Cylinder #8 came out in < 5 minutes.
The other problem I ran into doing this DIY was removing the E8 screw on the ignition coil for cylinder #7. I was using a 3/8” ratchet w an E8 socket and just could not get into the corner to loosen that last bolt. I went and bought a 1/4” E8 socket and presto, no problems getting into the tight space.
Top is the Hazet 4766-3, bottom is the 12mm swivel I bought from FCP Euro. There is a significant price difference but hey, we are working an a 100k truck, whats $90.00?
that's why the torque spec is there. That controls the index.
Fully agree. Try reading through some of the threads in other sections of this site where posters are wrapped around the axle on this and marking spark plugs with Sharpies to attempt perfect alignment.
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