Sparks plugs (a bit urgent)
 

Hello,
I need to change my spark plugs on my 2007 clk550 in the manual
Clk350:Bosch Platin Y 7 MPP 33 , NGK PLKR 6A
Clk550: Bosch F8 DPP 332 , NGK PFR 5R-11

Can't find the clk550's nowhere, however, I've read I could use the clk350's Bosch yr7mpp33, notice the 'R' in yr7mpp33 vs the manual's y7mpp33 without the 'R' which stands for resistor...
Question: is that ok to use yr7mpp33, besides the extra R? If yes Is that ok to use a part that is spec for clk350 not clk550?
I've also read I needed part 004159180326 or 0041594903. But looking for these sends me results back to the yr7mpp33 mentioned above.

What should I use for my clk550? Also any special tools, I have a 5/8 6inch socket and an extender ratchet.
Thank you for your time and previous advices.

I just changed plugs in my 550 yesterday. The plugs I used were NGK Iridium IX (LKR7AIX, stock no. 93911). This is an acceptable plug per NGK's website.

You are correct that a 5/8" spark plug socket is required, in addition to a torx bit to remove the coils (sorry, can't recall what size torx is needed). I saw that some people separate the coils from the wires before changing the plugs, but I didn't find this to be necessary, and was able to pop out the coil assembly with wires still attached.

Result: my car only has 62k miles, and the old plugs didn't look too bad. But the acceleration is noticably smoother now (not that is was bad before, but it's even better now). My car also has an occasional very slight rough idle, but this was present before the plug change and remains after, albeit slightly improved versus before. I also cleaned the throttle body, but this didn't affect the minor idle issue.

Anyhow, I hope this is of some help. Pics of new plugs box (for reference) and old plug are below.

https://cimg1.ibsrv.net/gimg/www.mbw...d51bc715b0.jpg
https://cimg2.ibsrv.net/gimg/www.mbw...746e973431.jpg

Thanks
 

It does help a lot . The torque for the wires is a t30 btw.
What torque specs did you use for the spark plugs? I've read 23nm somewhere.
The problem I have with the ones you installed, is that they're for the clk350, they're the new version of the 350's ones (from the manual).
I'm thinking that if they had different spark plugs, that's because of performance superior on the 550.
So isn't using the 350's limiting the 550 perf?
Just wondering.
Please let me know for the torque.
Thank you for your time

PS: by the way what city are you in? I live in L.A. and to this day still look for a mechanic experienced on these models. What year is yours btw?

I'll be totally honest with you, I didn't use a torque wrench. I felt the crush washer compress and then I tightened about a quarter turn or so. This method had historically worked fine for me and apparently fine for someone in a YouTube video I watched with a 550. I tightened the torx screws for the coils with a screwdriver only with a flip out handle for extra leverage. After verifying, it felt about the same as how they were originally tightened. I do have a torque wrench somewhere, but I just didn't think it was critical to use it here. Hopefully I don't regret this!

Regarding the plugs, do you think NGK's database is wrong? I'm a bit freaked out that I could have installed the wrong plugs. Although, isn't the V8 basically the same engine as the V6 but with 2 extra cylinders (I know there are minor differences like the throttle body size etc., but still very similar)? So it would make logical sense to me that the plugs would be the same.

My car is a 2008 550.

I take my car to Star Motor Werks in Costa Mesa. The owner (Chris) specializes in Mecedes and seems pretty honest so far based on my limited experience there. His prices definitely aren't the lowest, but his shop is really clean and my gut feeling is that my car is in good hands there. He wanted $400 to change plugs, which is why I opted to do it myself. I know it's kind of drive from L.A. though.

I changed spark plugs in my CLK 350 (2007) a few years ago, and ended up buying them from the MBZ dealer... like you, I wasn’t totally sure about the p/n so I went this route... I don’t remember them being horribly expensive but if I did it again, I would buy from amazon or other on-line retailer - ser below.

One recommendation, make sure you have a torque wrench and a thin-walled socket for spark plugs. You really don’t want to over tighten the spark plugs, plus not all sockets will fit in. A good torque wrench is maybe $40 on Amazon.

https://www.pelicanparts.com/More_In...9-19-03-26-M14

the M272 and M273 use the same spark plugs. They are basically the same engines, but of course the M273 has two extra cylinders and slightly different cylinder bores and strokes.