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Hi Folks. I'm due for a 40k mile service and figured I'd tackle replacing the engine air filter myself. However unlike M272 engines where the filters are in parallel (dual intakes), my C350 only has 1 intake. I figured out how to remove the filter, but to my surprise, there is another filter in front of the existing OEM one. Doing my research, online parts stores only list 1 engine air filter. I'm curious what this 2nd one is. Does anyone here have a clue?
I replaced my air filter with the K&N but the main filter was the only one there. When I pulled the airbox up there was no secondary filter as pictured in yours. Mine is a 2014 C350 sedan with the M276 engine. Perhaps that is an addition from the factory depending on the state where the car was originally sold?
I replaced my air filter with the K&N but the main filter was the only one there. When I pulled the airbox up there was no secondary filter as pictured in yours. Mine is a 2014 C350 sedan with the M276 engine. Perhaps that is an addition from the factory depending on the state where the car was originally sold?
Interesting. Mine was factory ordered, so perhaps that may have played a role. Regardless, I ended up reopening the box to have a 2nd look. After some research, I found out that this is similar to some C63 engines where they have permanent (non serviceable) charcoal filters. Pretty much everyone who's had their cars' tuned have also removed this for added power & sound (mod is called, "charcoal delete"). Apparently, this was originally designed to comply with some emissions regulation.
To my surprise, there was no easy way to remove the filter without essentially destroying it. It is held on by tabs inside that is melted into the plastic housing during assembly. As for effects after removal...there is definitely a change. Initial start up sound is different, and while I cannot measure any performance gains at this time (since I'm still babying it to see if I get a CEL), I do feel the throttle response has also changed when accelerating from a stop.
After my 40k Service B appointment, I'll top off the gas tank and do a bunch of Fuelly runs to see if it affected anything mileage wise (I pretty much took a break from fuelly since it was getting boring). I'm optimistic it will, since by the looks of it, the plastic housing around the charcoal filter pretty much blocked 25% of the main filter to begin with.
Good thing I decided to service this myself, since I have a feeling I may have accidentally discovered the X-pipe mod equivalent for the intake (except this one might actually produce gains).
Bah! So after an entire tank full (~400 miles) I finally got a CEL similar to what the C63 guys are complaining about.
Apparently "charcoal delete" + K&N filter may be too drastic of a change in regards of airflow. I've just reset the CEL, but unfortunately the 2 prior codes may be permanently stored in the ECU.
If the CEL comes back on again, I'l be going back to OEM paper, but if it continues to come back with stock filters, I may have to get an updated tune from OE. I'll continue to report my finding for you W204 M276'ers.
Thanks for the update. I'm fairly mechanically inclined although I'm no certified MB Tech; however the word "leak" doesn't sound like something caused by too much air flow. I think you'd be more likely to see a generic error message or a specific air flow measurement problem identified with the code? Perhaps with the charcoal delete the cutting or breaking of the plastic tabs is creates a leak within the airbox? Just a guess there. Someone else can chime in. Also like I said I didn't see a charcoal filter in my C350 airbox and the addition of a K&N has thrown no codes. I'll pull the window sticker out and see if there is anything about a possible factory charcoal delete noted on it.
Thanks for the update. I'm fairly mechanically inclined although I'm no certified MB Tech; however the word "leak" doesn't sound like something caused by too much air flow. I think you'd be more likely to see a generic error message or a specific air flow measurement problem identified with the code? Perhaps with the charcoal delete the cutting or breaking of the plastic tabs is creates a leak within the airbox? Just a guess there. Someone else can chime in. Also like I said I didn't see a charcoal filter in my C350 airbox and the addition of a K&N has thrown no codes. I'll pull the window sticker out and see if there is anything about a possible factory charcoal delete noted on it.
I only mention airflow because this is what some of the C63 guys are experiencing as well, and the immediate fix for the re-occurring CEL is to go with a less free flowing filter or a re-tune. Googling these error codes pointed me to other examples (non-Mercedes) of where the charcoal filters were removed as well.
As for tabs within the airbox, that is definitely not it. I just double checked last night and the airbox is completely sealed. The tabs are well within the confines of the rubber gasket surrounding the filter and makes no contact.
Too early to tell since there is not enough data points. I'm currently still on the 2nd tank. HOWEVER...if you click on my sig, you'll see a chart of of my past MPG figures. The last time I recorded was in Nov, 2014 @ 25.7MPG. My last tank with the charcoal removed and K&N filter was 26.3MPG. However with only 1 fill up, I can't honestly say if it has or hasn't.
Interesting, my 2012 C350 does not have that second filter. My guess is it's the CA emissions. My car was originally special ordered in Phoenix by the first owner.
I'm coming up to the point of changing my air filter as well. This was very helpful. I am curious to see if my c350 has the charcoal filter as well. By the way what filter did you get? The Mann Filter?
The intake box is held together by 3 screws on top and 2 tabs on the bottom. In order to open, you have to unscrew 2 bolts that hold the entire box within the engine bay and yank it off the clips at the bottom. Looking at my pics you can see that I rotated the entire box assembly to open it rather than disconnecting the air hoses.
I have a 2015 ML350 with the M276 engine (3.5 V6) and I am wanting to replace the engine air filter. This same engine is in many MB vehicles. Does anybody have a link to a how to video on replacing the engine air filter on the M276 engine, any vehicle model? All of the videos on youtube that I can find have the older M272 3.5 v6 engine air filter change (dual engine air filters, one on passenger side and one on driver side). For the M276, I think I have read threads on 3 different ways to replace the engine air filter. Some say you have to disconnect a sensor, but you have to be careful because you might break the plastic clip. Another said, you don't have to mess with the sensor or removing the box, you just unbolt the side, open it up and pull the filter out. Another said you unbolt the whole housing and rotate the housing, but you don't have to disconnect any sensor. So at this point, I'm just trying to figure out the simplest way to just replace the engine air filter. Any help would be appreciated! Thank you!
I just replaced mine thIs past weekend and it was quite simple. The initial plenum has to be unsnapped, no screws to remove. Then you just have to unscrew the three T20 torx head screws. The air box can then be lifted out and the filter can be removed. The screw closest to the windshield can be a little tricky to get to but a long driver works well.
I just replaced mine thIs past weekend and it was quite simple. The initial plenum has to be unsnapped, no screws to remove. Then you just have to unscrew the three T20 torx head screws. The air box can then be lifted out and the filter can be removed. The screw closest to the windshield can be a little tricky to get to but a long driver works well.
Thank you sandog1, just to make sure I'm understanding what you're saying. You removed those three screws and lifted the side cover off the airbox, but you didn't remove the entire airbox, is that right? I think the entire airbox is held on to the engine by 2 other screws.
When I first read the thread that mentioned what you said, I was really hoping it was that simple. But when I popped the hood and looked, that back screw closest to the windshield, is really tight to the passenger side firewall. There only seems to be a couple of inches between that screw head and the firewall. I think that may be why some people remove the 2 main screws that hold the entire airbox housing to the engine. Maybe they couldn't get that back screw out, without removing the entire airbox housing. One other thing are those three screws that hold the side cover on, a T20 or a T25?
I am really interested in this too.. Have a 2014 C300 which i had a 3.5 M276. I was trying to search the DIY thread but the pictures are not loading.. If anyone has a video or DIY instructions for it would be greatly appreciated. Thanks
Thank you sandog1, just to make sure I'm understanding what you're saying. You removed those three screws and lifted the side cover off the airbox, but you didn't remove the entire airbox, is that right? I think the entire airbox is held on to the engine by 2 other screws.
When I first read the thread that mentioned what you said, I was really hoping it was that simple. But when I popped the hood and looked, that back screw closest to the windshield, is really tight to the passenger side firewall. There only seems to be a couple of inches between that screw head and the firewall. I think that may be why some people remove the 2 main screws that hold the entire airbox housing to the engine. Maybe they couldn't get that back screw out, without removing the entire airbox housing. One other thing are those three screws that hold the side cover on, a T20 or a T25?
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