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  #1  
Old 01-09-2022, 09:02 PM
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K&N air filter?

Maybe it's been discussed here but anyone here run a K&N filter? Is it any good? Can it mess up anything in a old 300D. I'm starting to get sick of the stock filter I have on the car it always dangles and rattles. I've changed the mounts atleast twice now

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  #2  
Old 01-10-2022, 12:45 AM
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No, but I know what you mean, so I have the Ford truck can/filter that several others have done. The stock filter housing is absurd, must weigh 20 pounds and just shakes the whole car when it starts to rattle.

Also, there will now be a heated debate about whether K&N air filters will destroy your engine, just so you know.

Last edited by Rogviler; 01-10-2022 at 01:07 AM.
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  #3  
Old 01-10-2022, 01:26 AM
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Quote:
Originally Posted by Antique View Post
Maybe it's been discussed here but anyone here run a K&N filter? Is it any good? Can it mess up anything in a old 300D. I'm starting to get sick of the stock filter I have on the car it always dangles and rattles. I've changed the mounts atleast twice now
This had me initially confused because I used to use a K&N filter element that was a direct replacement for the stock element.

As you read further, I think you want to ditch the whole normal air filter setup enterally.

I think you are speaking of something like in the below threads: Washable Air Filter and Intake Mod , With Larger Breather

Air cleaner alternative

One of the AC hoses may or may not be in the way.

I used ABS Plumbing pipes and a rubber sleeve. There used to be some sort of steel elbow with filter you could buy, and others have used a rubber elbow.

In another thread of mine in the past I asked if you only had to use the special K&N cleaner on the K&N air filter I used and I got highly vilified for using it at all. Lot of lively popularized articles on that subject.

Also, in the past many members are against the use of the various types of cone filters with foam elements that usually come with the kits with an elbow.

However, others have used fabricated or used the elbow setup with regular paper element air filter where they found one that fit.

The last advice is fix what is causing your shaking issues. After I fixed the shaking issue on mine, I never had any problems with the stock air filter housing.

Note that I went to the stock sized K&N filter because engine blowby would saturate the paper filters with oil vapor.
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  #4  
Old 01-11-2022, 12:28 AM
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The factory air filter setup is not good .

Even on an engine that runs and idles smooth as glass, the rubber supports fail from time to time .

K & N filters or their brethren don't actually filter much so yes, they'll wear the engine out faster but then again, few ever keep the vehicle long enough to tell .

Re situating the filter is a wise thing to do many threads on it .

Me, I just use factory rubbers and change them every few years .
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  #5  
Old 01-11-2022, 10:41 AM
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There was another controversy about the cone shape filters because they draw air from under the hood not from outside.

I measured this with oven thermometer that had a long cable. The under the hood temp spikes up at an intersection but that heat, and the reduced air density happens at idle.

As soon as you start moving there is turbulence and the under the hood temp drops quickly. So, I don't see the air temp as causing any practical issue.

From an old post of mine: I am posting this to correct the above stuff. Apparently my memory of the test was not so good. I found what I previously posted so here that is:

"I have a digital Thermometer with a probe long enough the I put it under the hood at the end of my air filter horn (Federal air filter housing) which would be about where one of those Cone type filters would be under the hood and I ran the car on the Freeway to get it hot and drove around town and sat at some long Traffic Signals. I also put the probe all the way up front where the cold air would go into the air filter and drove around again.

I was surprised to find out that while you are moving even in slow traffic the outside and under the hood temperature is not significantly different. However, when you idle the under the hood temperature went up from the 76 degree outside temp to 98-110 degrees under the hood.

My conclusion is that you do no harm by having the end of the air intake system under the hood as it only made a differance when you sat at idle. When you start moving there is enough air flow that you get the colder outside air anyway.

If you want to try the experiment youself (cheaper than a new intake system) I bought the thermometer at Target and it has a 36 inch long steel braided covered wire. You are supposed to stick the probe in what you are cooking in the oven to measure the inside temp of it and run the cable out of the oven door and the Digital display has magnets on the back to stick to you oven/car hood. I believe it cost around $16.
Get someone with good eyes to ride along with you to do the reading of the thermostat."
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  #6  
Old 01-11-2022, 10:51 AM
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Some place in the below thread there is lots of controversy on the K&N air filters.

Washing K&N air filters

This was my favorite post from the above thread: "It's just obvious hearsay unless you have some first hand information to back up your statement above.

I have been using K&N filters for 25 years without a problem. Longer than you have been alive, eh?

I installed hundreds of them at dealerships, Porschasports, and now the shop where I work now. Fifteen Porsche engines in sand buggys all used K&N at the Baja 1000 as well as many other racers there. I don't remember seeing anything but K&N filters on the motorcycles. Foam blankets were used on the dustiest roads.

I have torn down some high mileage engines and have never seen the tell tale vertical scratches on the cylinder walls denoting hard particle injestion.

I've read several reports that say the K&N filters don't filter as well as others. In the real world that doesn't seem to mean squat.

Wash the elements out in three gallons of warm water with two tablesppons of Dawn detergent. It cuts grease well. Sun dry and oil with Marvel Mystery oil put in a spray bottle."
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  #7  
Old 01-11-2022, 11:11 AM
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this is what I did
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K&N air filter?-img_20210406_140922.jpg  
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  #8  
Old 01-11-2022, 12:10 PM
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I used to run a K&N in the stock housing. Didn't seal well and so didn't filter well. I went back using OE MB air filters. They seal perfectly. If I were you, I would rotate them 90 degrees every 3000 miles and replace them after a full rotation (12K miles).

Our air filter housings like to concentrate oil and dirt in small sections of the air filter - this technique ensures that filtration and airflow are always optimal.
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  #9  
Old 01-11-2022, 01:01 PM
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K&N and me.....

Quote:
Originally Posted by Screwdriva View Post
I used to run a K&N in the stock housing. Didn't seal well and so didn't filter well. I went back using OE MB air filters. They seal perfectly. If I were you, I would rotate them 90 degrees every 3000 miles and replace them after a full rotation (12K miles).

Our air filter housings like to concentrate oil and dirt in small sections of the air filter - this technique ensures that filtration and airflow are always optimal.
This is great advice! Agree 100%. I've used K&N on a few of my vehicles in the past. My '83 240D had one installed when I bought it. My impression of K&N, in a word, meh. Not worth the hassle or the price. Noticed zero difference in "performance". I don't know about anyone else on this forum, but if I'm paying upwards of $100 (filter doesn't include cleaning/oiling kit) for an AIR FILTER, I'd probably be checking in with a psychiatrist! I don't have Marvel Mystery oil in my garage and my wife doesn't use Dawn (more extraneous expense for the vaunted K&N)

Simple math will tell you, if you care about your expenses, K&N is a waste of time and money. You can buy a "normal" everyday air filter for around $10-12. Let's say you change it every 20,000 miles. For the price of a K&N you can drive 200,000 miles with a normal filter (probably more).

And then there's the hassle of cleaning/oiling it. Yeah, it's no big deal, but it takes a lot more time than pulling a standard filter out of the box and putting into your car. First you gotta wash it. Then, let it dry. Just "put it in the sun". Well, it's 12 degrees in my "neck of the woods", today. I could "put it in the sun" all day and just end up with a K&N ice sculpture.

Lastly, we have the claimed "performance gain". K&N says they flow more air. The only way to do that is to have a less restrictive filter media. Less restriction means bigger "holes", which translates to more dirt bypassing the filter. Simple physics. And, as everyone should know, "you can't change the laws of physics". BTW, I've never noticed a "seat of the pants" performance gain from a K&N. Conversely, I've also never noticed a degradation in performance when going back to a standard paper type filter.

Of course, this "rant" is focused on normal everyday driving in standard unaltered vehicles. If professional racing and corporate sponsorship is the subject, then yes, maybe the K&N offers some benefits. (like free products and no cleaning hassle.....heh heh)
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  #10  
Old 01-13-2022, 11:26 PM
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Quote:
Originally Posted by Screwdriva View Post
I used to run a K&N in the stock housing. Didn't seal well and so didn't filter well. I went back using OE MB air filters. They seal perfectly. If I were you, I would rotate them 90 degrees every 3000 miles and replace them after a full rotation (12K miles).

Our air filter housings like to concentrate oil and dirt in small sections of the air filter - this technique ensures that filtration and airflow are always optimal.
When I ran the stock type K&N I realized the rubber area that sealed was harder and I put a bead of sides of the air filter housing were the sealing area on the filter matched and let that cure. That gave a nice soft area for the filter sealing edge to seal on.
If that had to be renewed it was still cheaper compared to buying a new throw away air filter.
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  #11  
Old 01-14-2022, 12:56 AM
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Originally Posted by 123boy View Post
This is great advice! Agree 100%. I've used K&N on a few of my vehicles in the past. My '83 240D had one installed when I bought it. My impression of K&N, in a word, meh. Not worth the hassle or the price. Noticed zero difference in "performance". I don't know about anyone else on this forum, but if I'm paying upwards of $100 (filter doesn't include cleaning/oiling kit) for an AIR FILTER, I'd probably be checking in with a psychiatrist! I don't have Marvel Mystery oil in my garage and my wife doesn't use Dawn (more extraneous expense for the vaunted K&N)

Simple math will tell you, if you care about your expenses, K&N is a waste of time and money. You can buy a "normal" everyday air filter for around $10-12. Let's say you change it every 20,000 miles. For the price of a K&N you can drive 200,000 miles with a normal filter (probably more).

And then there's the hassle of cleaning/oiling it. Yeah, it's no big deal, but it takes a lot more time than pulling a standard filter out of the box and putting into your car. First you gotta wash it. Then, let it dry. Just "put it in the sun". Well, it's 12 degrees in my "neck of the woods", today. I could "put it in the sun" all day and just end up with a K&N ice sculpture.

Lastly, we have the claimed "performance gain". K&N says they flow more air. The only way to do that is to have a less restrictive filter media. Less restriction means bigger "holes", which translates to more dirt bypassing the filter. Simple physics. And, as everyone should know, "you can't change the laws of physics". BTW, I've never noticed a "seat of the pants" performance gain from a K&N. Conversely, I've also never noticed a degradation in performance when going back to a standard paper type filter.

Of course, this "rant" is focused on normal everyday driving in standard unaltered vehicles. If professional racing and corporate sponsorship is the subject, then yes, maybe the K&N offers some benefits. (like free products and no cleaning hassle.....heh heh)
I was not looking or expecting any performance gain.

The other part of the paragraph is not exactly true. The K&N does not have straight through holes it has a cotton media with nooks and crannies. When the nooks and crannies are oiled properly the particulates are supposed to enter the filter where they impact against the oil and stick there.

To some degree that is what oil bath air filters do. The is a flow and there is a change of direction in the flow and the particulates are supposed to keep going straight into the oil where they are trapped in the oil.

In oil bath oil filter, the change of direction is in the metal ducting. In the K&N the change of the direction happens in the cotton media which has some depth to it.

Ask yourself level of filtration is there in you stock Mercedes filter? And go to some of the filter manufacturer sites and see if you can find out.

When I tried to look that up, I found the Car air filters did not list what micron level they filtered down to. However, with Industrial air filters they gave a micron level of filtration.
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  #12  
Old 01-14-2022, 01:02 AM
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When you look up car air filters, they do list a cubic feet per-minute rating. The on a 84 300D Federal air filter it has a much higher cfm rating compared to what the engine can move maxed out and especially at normal engine speeds. So, I am not seeing that there can be a performance improvement over the stock filter.

Obviously more square inches of filter element would take longer to get restricted enough to effect performance.
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  #13  
Old 01-19-2022, 12:42 AM
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I used to own a chassis dynamometer business. I did more than 100 back to back comparisons of K & N replacement filters vs stock paper filters. Only one car, a VW Corrado, ever made more power using the K & N filter. Most cars lost a little power.

When servicing VW cars using K & N filters there was always some dust accumulation in the intake manifold and on the airflow sensor. This dust was never evident using the stock paper air filters.

My conclusion is that K & N filters are inferior for stock applications.

K & N got their name with off road motorcycles where the pulsations from the carburetors kept dirt from caking up the filter. They work well for off road situations where the filter really loads up with dirt. A paper filter will clog quickly in the same circumstances.
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Old 01-19-2022, 12:52 PM
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On the VW forums there have been long, drawn out discussions about K&N filters. Testing showed they didn't flow any better than a stock filter, didn't make any more power, and filtered less resulting in mass airflow sensor failure.

-J
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  #15  
Old 01-19-2022, 02:42 PM
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As I, not so eloquently, stated in my post......more flow equals less filter. Cant change the laws of physics. A couple great responses there. Real world testing, proper procedures, accurate quantifiable results. IMHO, K&N belongs in the "snake oil" file. Only my opinion. I'll take a Mann over K&N any day....and twice on Sunday.

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