US-spec 128i Air filter replacement. The DIY nobody needed.

wolfe · 09-17-2011, 11:56 AM

This one's pretty straightforward. Apparently the Euro cars have a different airbox with a cylindrical filter, and you can change it without removing the airbox. I took a few pictures when I changed the filter on my 128i in case they're helpful to anyone.

The only parts you'll need are a new air filter element, and tools include a 10mm socket, flat head screwdriver or small socket & extension, a shop vac or compressed air or a soft paintbrush (for cleaning), a plastic pry tool if you care about not scratching stuff, and shop towels. Please note that the captions correspond to the image below, not above.

1. remove the two 10mm bolts (#1). #2 shows the MAF sensor location, and #2 shows the hose clamp which holds the rubber intake boot to the back of the airbox.

2. Carefully pry up the tab with a plastic pry tool, then slide the wiring plug out. I wrapped the plug in painters tape to keep dust and dirt out, but that's probably overkill.

3. Clean the area around the boot well. You want to do everything you can here to avoid dropping dirt, dust, and grit into the intake piping. Then loosen the hose clamp sufficiently.

4. Moving to the front of the car, there's a flexible connector where the airbox joins the front air diverter. Carefully pry up the tabs on the left and right side, then squeeze the airbox section to release the tabs.

5. Once the tabs are free you can pull back the flexible connector a bit. It's not massively flexible but it'll move enough to let you get the airbox out.

6. The airbox has a lip underneath it that sticks out another third of an inch or so. This makes it a bit more tricky to clear the flexible connector but it's not too bad. Lift this side of the airbox up so it's resting on the section still attached to the car.

7. With the hose clamp loosened, carefully slide the intake boot back off the airbox. Now the airbox is no longer attached to the car, but it still takes a bit of wiggling to get it removed.

8. I found that rotating the airbox back slightly and lifting it out was easiest. You have to wiggle the tab where you removed the bolts because that sits underneath a bit of the bodywork. There's no additional hidden clips etc. so once you've got it free just lift it out of the car.

9. Now the airbox is removed, clean up the intake boot and the front air diverter box connections. Do not use compressed air for this. I used shop towels and some lint roller sheets. A clean shop vac would also work very well I think. If you're going way overboard here or are working outdoors, I'd cover the open intake boot with a ziploc and rubber band.

10. With the airbox removed, set it down on something to protect it and slacken the bolts around the edge with a T25 torx bit. You don't have to remove the bolts all the way as I put on the image, they will remain in the 'lid' of the airbox. Be careful not to get the MAF sensor dirty as these are pretty sensitive. I was going to clean it with CRC MAF cleaner but the new design meant I'd have had to remove it completely.

11. With the lid removed, take out the replaceable air filter (mine was yellow paper with orange rubber trim, you can't miss it

. Interestingly on this car it had what I assume is a secondary air filter, much like a household AC filter that was part of the lid. I didn't see any way to remove or clean this so I left it alone.

12. When I removed the air filter element, I found a lot of debris on the 'dirty' (unfiltered) side of the airbox. I decided to clean this out, again a paintbrush and/or shop vac/compressed air will work. You could probably even wash it if you had the time to let it dry thoroughly. Clean the mating surfaces of the airbox and the lid to make sure there's no grit or dirt that could compromise the seal.

Once you've got that clean, install the new air filter, making sure it's seated properly the whole way around. It's quite snug and I had to wiggle it a bit around the narrow end to get the paper element fully seated. Refit the lid and tighten all the torx bolts, going in a diagonal pattern. Don't overtighten these as you could deform the airbox.

Once the airbox is back together, rotate it back into the car by tilting the back down. Make sure the rubber intake boot isn't forced down by the airbox, try and pull it back so it's in roughly the right place. Reconnect the flexible coupling on the front side of the airbox, and wiggle the airbox to get the bolt tabs back in the right place. I didn't reinstall the bolts yet but you probably could.

Working on the back of the airbox, pull the intake boot back onto it's mounting point. This requred a bit of patience. If you can, reach underneath to make sure it's seated on the underside too. A small mirror might help here if you can't reach. Hold the intake boot up against the airbox, and tighten the hose clamp. There's two rubber locating blocks on the boot, make sure you get the clamp screw inbetween them. I assume this solves the problem on older bmw's where these clamps were tightened up before the engine was installed, then were very difficult to access after the fact. Nice feature.

Reconnect the MAF wiring plug, ensuring the tab snaps into place. Doesn't require much force at all. You could grease the outside of the rubber seal on the plug with a little silicone grease if you wanted to or live somewhere very wet.

Once you've checked it's all back in place correctly, reinstall the two bolts if you didn't already. Again these don't need to be super tight as they simply hold the rubber mounts in place. You're done!

Here's what my original air filter looked like after 17,000 miles. Quite a lot of visible dirt so glad I changed it out.

Note: the DIY ends here, all the pictures below are just the attached images used in the post.

Dackelone · 09-17-2011, 12:14 PM

Nice DIY writeup Wolfe.

When I recently replace my air filter in my 135i - I also saw a simular amount of sand and small rocks. Makes me cringe to think IF I had a K&N type air filter in there. ALL those rocks would be in my engine! Nein Danke. I will stick to using a paper filter element.

wolfe · 09-17-2011, 12:43 PM

Agreed, any tiny bump in horsepower or throttle response just isn't worth the risk to me either.

sonicbimmer19 · 09-17-2011, 01:10 PM

thanks for posting this Wolfe!! I'll need this once my warrenty/maintenance runs out soon.

HISI808 · 09-17-2011, 05:19 PM

Nicely done. Quick question, what software program are you using to create the text and arrows? It's very legible and I could use this for my work when creating documentation.

wolfe · 09-17-2011, 05:54 PM

I'm using photoshop, but you could probably get the same effect with other software. The font is called 'chunk five' and it's free, and the style is simply yellow text/arrows with around a 5 pixel black outline on everything.

brosher · 09-18-2011, 07:47 AM

Thanks for this.

Bishop200 · 03-20-2012, 06:47 PM

Excellent write-up, thank you. Why does have to be so b****y complicated though? On my Integra, it was a two second job. Sigh.

flzrider · 03-20-2012, 07:52 PM

wolfe, you do some great DIYs. I especially like the family guy reference

Adam135 · 03-20-2012, 10:20 PM

Quote:

Originally Posted by Dackelone

Nice DIY writeup Wolfe.

When I recently replace my air filter in my 135i - I also saw a simular amount of sand and small rocks. Makes me cringe to think IF I had a K&N type air filter in there. ALl those rocks would be in my engine! Nein Danke. I will stick to using a paper filter element.

What am I missing here? I have a K&N drop-in filter, how are rocks going to get through the element?

cedavis34 · 03-24-2012, 09:44 PM

Quote:

Originally Posted by Adam135

What am I missing here? I have a K&N drop-in filter, how are rocks going to get through the element?

They are exaggerating a slight bit, but the more informed people know that K&N type filters do in fact flow better, however they also allow more dirt through. Paper type filters do a better job filtering, but do not flow quite as well.

There are probably many different places to read this, but I just read it recently on www.bobistheoilguy.com.

I currently have a Helene filter in my car, but I'll probably go back to my paper element because I do not really need the 1 or 2 horsepower that I might be gaining.

Adam135 · 03-24-2012, 09:46 PM

Quote:

Originally Posted by cedavis34

They are exaggerating a slight bit, but the more informed people know that K&N type filters do in fact flow better, however they also allow more dirt through. Paper type filters do a better job filtering, but do not flow quite as well.

There are probably many different places to read this, but I just read it recently on www.bobistheoilguy.com.

I currently have a Helene filter in my car, but I'll probably go back to my paper element because I do not really need the 1 or 2 horsepower that I might be gaining.

Got it. I guess I may reconsider paper air filters.

You can get the Mahle LX1564 on eBay for $33 shipped (link).

RIbimmer · 03-31-2012, 10:37 AM

Thanks Wolfe. Excellent DIY. You inspired me to get a new Mann air filter and install it myself.

mleskovar · 03-21-2013, 04:52 PM

Resurrect....

Anyone find out what's the purpose of the secondary air filter? I'm wondering if it's for flash/flame suppressing? Is it supposedly lifetime?

bmw1racer · 03-21-2013, 10:42 PM

Wow, I didn't know this DIY existed... Good info to know when the time comes.

BMW sure did make changing the air filter one freaking tedious task.

Bookmarking this now.

andrey_gta · 03-22-2013, 09:20 AM

Yep I used this DIY twice
Once to do the Manifold mod, at that time I also vacuumed the OEM filter
Then when I did Euro box

Isdaako · 03-28-2013, 09:05 AM

Great thread title. Great thread content. Thanks!

wolfe · 04-09-2013, 08:51 PM

Just noticed one of the image links was broken. It's fixed now

sonicbimmer19 · 04-24-2013, 07:14 PM

just used this DIY to replace my air filter after 38xxx miles and 5 years. Thanks Wolfe!

To my knowledge, air filters are supposed to be replaced every 3 oil changes, or about 45000 miles or 3 years but I think the actual mileage is more important. But, my air filter was quite dirty so maybe next time I'll change it a little bit earlier.

pj.rodriguez · 08-09-2013, 04:19 PM

Awesome DIY. Just used this 5 minutes ago. Thanks for the info!

JimD · 08-11-2013, 05:30 PM

Thanks for the DIY.

I will remove the secondary filter when I install my first new element - which may well be a K&N. My understanding is the secondary filter is charcoal and thought to do something about odors or emissions or something - it is not an effective filter for the engine. I've read about K&Ns not filtering as well and also damaging MAF sensors if over oiled but I have one on my other car and I like it.

Jim

Dafttt · 08-12-2013, 02:04 AM

Great write up, used it today for my Eurobox. Thanks!

09-17-2011, 11:56 AM	#1
wolfe Captain 134 Rep 613 Posts Drives: e82 / e70 / r56 / r60 Join Date: Apr 2010 Location: USA iTrader: (1)	US-spec 128i Air filter replacement. The DIY nobody needed. This one's pretty straightforward. Apparently the Euro cars have a different airbox with a cylindrical filter, and you can change it without removing the airbox. I took a few pictures when I changed the filter on my 128i in case they're helpful to anyone. The only parts you'll need are a new air filter element, and tools include a 10mm socket, flat head screwdriver or small socket & extension, a shop vac or compressed air or a soft paintbrush (for cleaning), a plastic pry tool if you care about not scratching stuff, and shop towels. Please note that the captions correspond to the image below, not above. 1. remove the two 10mm bolts (#1). #2 shows the MAF sensor location, and #2 shows the hose clamp which holds the rubber intake boot to the back of the airbox. 2. Carefully pry up the tab with a plastic pry tool, then slide the wiring plug out. I wrapped the plug in painters tape to keep dust and dirt out, but that's probably overkill. 3. Clean the area around the boot well. You want to do everything you can here to avoid dropping dirt, dust, and grit into the intake piping. Then loosen the hose clamp sufficiently. 4. Moving to the front of the car, there's a flexible connector where the airbox joins the front air diverter. Carefully pry up the tabs on the left and right side, then squeeze the airbox section to release the tabs. 5. Once the tabs are free you can pull back the flexible connector a bit. It's not massively flexible but it'll move enough to let you get the airbox out. 6. The airbox has a lip underneath it that sticks out another third of an inch or so. This makes it a bit more tricky to clear the flexible connector but it's not too bad. Lift this side of the airbox up so it's resting on the section still attached to the car. 7. With the hose clamp loosened, carefully slide the intake boot back off the airbox. Now the airbox is no longer attached to the car, but it still takes a bit of wiggling to get it removed. 8. I found that rotating the airbox back slightly and lifting it out was easiest. You have to wiggle the tab where you removed the bolts because that sits underneath a bit of the bodywork. There's no additional hidden clips etc. so once you've got it free just lift it out of the car. 9. Now the airbox is removed, clean up the intake boot and the front air diverter box connections. Do not use compressed air for this. I used shop towels and some lint roller sheets. A clean shop vac would also work very well I think. If you're going way overboard here or are working outdoors, I'd cover the open intake boot with a ziploc and rubber band. 10. With the airbox removed, set it down on something to protect it and slacken the bolts around the edge with a T25 torx bit. You don't have to remove the bolts all the way as I put on the image, they will remain in the 'lid' of the airbox. Be careful not to get the MAF sensor dirty as these are pretty sensitive. I was going to clean it with CRC MAF cleaner but the new design meant I'd have had to remove it completely. 11. With the lid removed, take out the replaceable air filter (mine was yellow paper with orange rubber trim, you can't miss it . Interestingly on this car it had what I assume is a secondary air filter, much like a household AC filter that was part of the lid. I didn't see any way to remove or clean this so I left it alone. 12. When I removed the air filter element, I found a lot of debris on the 'dirty' (unfiltered) side of the airbox. I decided to clean this out, again a paintbrush and/or shop vac/compressed air will work. You could probably even wash it if you had the time to let it dry thoroughly. Clean the mating surfaces of the airbox and the lid to make sure there's no grit or dirt that could compromise the seal. Once you've got that clean, install the new air filter, making sure it's seated properly the whole way around. It's quite snug and I had to wiggle it a bit around the narrow end to get the paper element fully seated. Refit the lid and tighten all the torx bolts, going in a diagonal pattern. Don't overtighten these as you could deform the airbox. Once the airbox is back together, rotate it back into the car by tilting the back down. Make sure the rubber intake boot isn't forced down by the airbox, try and pull it back so it's in roughly the right place. Reconnect the flexible coupling on the front side of the airbox, and wiggle the airbox to get the bolt tabs back in the right place. I didn't reinstall the bolts yet but you probably could. Working on the back of the airbox, pull the intake boot back onto it's mounting point. This requred a bit of patience. If you can, reach underneath to make sure it's seated on the underside too. A small mirror might help here if you can't reach. Hold the intake boot up against the airbox, and tighten the hose clamp. There's two rubber locating blocks on the boot, make sure you get the clamp screw inbetween them. I assume this solves the problem on older bmw's where these clamps were tightened up before the engine was installed, then were very difficult to access after the fact. Nice feature. Reconnect the MAF wiring plug, ensuring the tab snaps into place. Doesn't require much force at all. You could grease the outside of the rubber seal on the plug with a little silicone grease if you wanted to or live somewhere very wet. Once you've checked it's all back in place correctly, reinstall the two bolts if you didn't already. Again these don't need to be super tight as they simply hold the rubber mounts in place. You're done! Here's what my original air filter looked like after 17,000 miles. Quite a lot of visible dirt so glad I changed it out. Note: the DIY ends here, all the pictures below are just the attached images used in the post. Attached Images Last edited by wolfe; 06-23-2018 at 07:18 PM.. Reason: updated photo hosting
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09-17-2011, 12:43 PM	#3
wolfe Captain 134 Rep 613 Posts Drives: e82 / e70 / r56 / r60 Join Date: Apr 2010 Location: USA iTrader: (1)	Agreed, any tiny bump in horsepower or throttle response just isn't worth the risk to me either.
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09-17-2011, 01:10 PM	#4
sonicbimmer19 Lieutenant 72 Rep 487 Posts Drives: E88 and F32 Join Date: Jan 2011 Location: Los Angeles, CA iTrader: (1)	thanks for posting this Wolfe!! I'll need this once my warrenty/maintenance runs out soon.
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09-17-2011, 05:19 PM	#5
HISI808 Second Lieutenant 11 Rep 239 Posts Drives: 2011 AW 128i M-Sport Join Date: Jul 2010 Location: Hawaii iTrader: (4)	Nicely done. Quick question, what software program are you using to create the text and arrows? It's very legible and I could use this for my work when creating documentation.
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09-17-2011, 05:54 PM	#6
wolfe Captain 134 Rep 613 Posts Drives: e82 / e70 / r56 / r60 Join Date: Apr 2010 Location: USA iTrader: (1)	I'm using photoshop, but you could probably get the same effect with other software. The font is called 'chunk five' and it's free, and the style is simply yellow text/arrows with around a 5 pixel black outline on everything.
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09-17-2011, 12:14 PM	#2
Dackelone European Editor 10528 Rep 22,992 Posts Drives: N54 e82 Join Date: Feb 2010 Location: Bayern, Germany iTrader: (1)	Nice DIY writeup Wolfe. When I recently replace my air filter in my 135i - I also saw a simular amount of sand and small rocks. Makes me cringe to think IF I had a K&N type air filter in there. ALL those rocks would be in my engine! Nein Danke. I will stick to using a paper filter element.
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09-18-2011, 07:47 AM	#7
brosher Enlisted Member 2 Rep 34 Posts Drives: 128i ZSP 6SPD Join Date: Jul 2009 Location: NY iTrader: (0)	Thanks for this.
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03-20-2012, 06:47 PM	#8
Bishop200 Enlisted Member 2 Rep 48 Posts Drives: 128i 6mt, sports pkg Join Date: Jun 2009 Location: Victoria, BC, Canada iTrader: (0)	Excellent write-up, thank you. Why does have to be so b****y complicated though? On my Integra, it was a two second job. Sigh.
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03-20-2012, 07:52 PM	#9
flzrider Captain 50 Rep 739 Posts Drives: AW 1M Join Date: Oct 2005 Location: Miami, FL iTrader: (1)	wolfe, you do some great DIYs. I especially like the family guy reference __________________
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03-31-2012, 10:37 AM	#13
RIbimmer Private First Class 24 Rep 179 Posts Drives: '09 128i, '17 i3 BEV Join Date: Sep 2008 Location: Pennsylvania iTrader: (0)	Thanks Wolfe. Excellent DIY. You inspired me to get a new Mann air filter and install it myself. __________________
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03-21-2013, 04:52 PM	#14
mleskovar Lieutenant 79 Rep 435 Posts Drives: '18 230i Join Date: Dec 2007 Location: Huntington Beach, CA iTrader: (0)	Resurrect.... Anyone find out what's the purpose of the secondary air filter? I'm wondering if it's for flash/flame suppressing? Is it supposedly lifetime?
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03-21-2013, 10:42 PM	#15
bmw1racer bimmerphile, technogeek 998 Rep 3,784 Posts Drives: 2012 E82 6MT Sport Join Date: Jun 2011 Location: SoCal iTrader: (0) Garage List 2012 BMW 128i Coupe [0.00]	Wow, I didn't know this DIY existed... Good info to know when the time comes. BMW sure did make changing the air filter one freaking tedious task. Bookmarking this now. __________________
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03-22-2013, 09:20 AM	#16
andrey_gta Brigadier General 298 Rep 4,040 Posts Drives: 130i coupé ;) Join Date: Nov 2011 Location: Bimmerpost iTrader: (1) Garage List 2008 BMW 128i [10.00]	Yep I used this DIY twice Once to do the Manifold mod, at that time I also vacuumed the OEM filter Then when I did Euro box __________________ 128i Sport 6MT converted to Euro 130i spec, 3.73 diff, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE In-progress: //M front arm, M3 rack, e36M lip Wishlist: Coils, n55 mnts, headers, LSD, e60 finn diff "The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is
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03-28-2013, 09:05 AM	#17
Isdaako Private First Class 1 Rep 160 Posts Drives: 128i Convertible Join Date: Sep 2012 Location: Devils Tower iTrader: (0)	Great thread title. Great thread content. Thanks!
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04-09-2013, 08:51 PM	#18
wolfe Captain 134 Rep 613 Posts Drives: e82 / e70 / r56 / r60 Join Date: Apr 2010 Location: USA iTrader: (1)	Just noticed one of the image links was broken. It's fixed now
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04-24-2013, 07:14 PM	#19
sonicbimmer19 Lieutenant 72 Rep 487 Posts Drives: E88 and F32 Join Date: Jan 2011 Location: Los Angeles, CA iTrader: (1)	just used this DIY to replace my air filter after 38xxx miles and 5 years. Thanks Wolfe! To my knowledge, air filters are supposed to be replaced every 3 oil changes, or about 45000 miles or 3 years but I think the actual mileage is more important. But, my air filter was quite dirty so maybe next time I'll change it a little bit earlier.
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08-09-2013, 04:19 PM	#20
pj.rodriguez Lieutenant Colonel 84 Rep 1,623 Posts Drives: Alpine White 128i Cabrio Join Date: Jun 2013 Location: Toronto, Ontario, Canada iTrader: (9) Garage List 2008 BMW 128i E88 [9.00]	Awesome DIY. Just used this 5 minutes ago. Thanks for the info!
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08-11-2013, 05:30 PM	#21
JimD Brigadier General 368 Rep 3,547 Posts Drives: 128i convertible Join Date: Apr 2009 Location: Lexington, SC iTrader: (0)	Thanks for the DIY. I will remove the secondary filter when I install my first new element - which may well be a K&N. My understanding is the secondary filter is charcoal and thought to do something about odors or emissions or something - it is not an effective filter for the engine. I've read about K&Ns not filtering as well and also damaging MAF sensors if over oiled but I have one on my other car and I like it. Jim __________________ 128i Convertible, MT, Alpine White, Black Top, Taupe Leatherette, Walnut, Sport Ordered 5/22/09, Completed 6/4/09, At Port 6/9/09, On the Georgia Highway 6/13/09, Ship Arrived Charleston 6/24/09 at 10pm, PCD 7/21/09
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08-12-2013, 02:04 AM	#22
Dafttt Captain 33 Rep 691 Posts Drives: 128i 6MT Join Date: Jan 2012 Location: Malibu iTrader: (0)	Great write up, used it today for my Eurobox. Thanks!
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