Why not to use K&N filters in offroad vehicles (or work vans

[lighthammer]

So I decided to try an experiment with a K&N drop in panel filter in my 2010 4x4 6-speed manual Navara. Wanted to see how much power gains and fuel economy gains would be had with a K&N free-breathing filter.

Unfortunately I also decided to go off-roading with it installed. I thought to myself, hey I have a snorkel on my truck, and the airbox is pretty well sealed, what could go wrong? Also, I have a habit of turning the snorkel head backwards whenever playing in water/slushy mud to avoid getting anything into the ram-air intake of the snorkel.



The results speak for themselves:








Looking into the airbox, you can see the port coming from the snorkel is clean - so no mud came through there. Instead, the poorly-fitting K&N panel filter was unable to form a proper seal around the edges of the air-box, thus allowing muddy water to enter the box and potentially the turbocharger.



If you look carefully, you can see the MAF-sensor coated with mud.








So - no matter what anyone tells you..... NEVER LISTEN TO ANYONE WHO TELLS YOU A K&N FILTER IS BEST FOR YOUR TRUCK, ESPECIALLY IF YOU TAKE YOUR TRUCK OFFROADING.

This for me is proof enough that the horsepower and boost-response gains are not worth potentially destroying the engine over. Just buy the f*cking air filter, you cheap bastards (that's what I told myself with my inside-voice when I saw how dirty my airbox was)..... $140 for a Navara air filter at ROC Bamboo, genuine nissan.


Luckily, the turbo was undamaged, and was making good boost and spooling up well. The only symptoms from the mud-inhalation so far have been a slight decrease in overall power, and lots of black smoke when pulling off from standstill or under heavy acceleration. Cruising at highway speeds doesn't produce black smoke, and the boost is still there when I want it. Fuel economy is still the same, and I'm surprised the truck's ECU hasn't gone into limp-mode with how well-coated the MAF sensor diode is. Hopefully all those symptoms will clear up once the maf sensor is cleaned and the ECU reset back into factory/learning mode.



Thus began the cleanup process.
Step 1. - scrap down all the air filter and air box elements
Step 2. - wash everything (except the air filter... that piece of sheit gets thrown away, or it's free to whoever wants it). Then use CRC MAF sensor cleaner or at least CRC Contact cleaner (second best thing and still works well) to spray out the MAF sensor throughly, taking care not to damage the diode.
Step 3. Allow to filter system dry in sun for at least an hour
Step 4. Reassemble air filtration system. Don't forget to do a hard reset on the ECU to being back the maps to stock and put the ECU back into learning mode, since the maf sensor will now be cleaned.
Step 5. Crack open cold drink and kick yourself in the butt for letting people fool you into buying into the K&N bullsheit (at least for OFFROAD vehicles and vehicles exposed to water/mud).










Checking to see if the box was still water-tight.... yup, it was!!


Ok, gonna go reassemble everything.... I'll update you guys later on how everything works out.


Keep On Truckin.

[VexXx Dogg]

wow.
how effective would a paper filter be against that level of muddy water?

[lighthammer]

well here's the thing - when I had the stock filter in, it never let in anything into the upper part of the airbox.

The problem was caused by a poorly-fitting K&N filter.... that was rated for the Navara 2.5 YD25DDTi engine.

The edges of the k&N filter don't have the same rubber seal around it as the stock nissan filter which has an inner rubber seal for better protection against side-seepage of water/mud.... see the images below..







On the right is the stock nissan filter that I had before, and on the left is the K&N replacement. Notice the difference in the edges of the filter - and lack of proper sealing on the K&N.






Because of this, I no longer have any faith in K&N filters at all.... well at least for offroad vehicles.

[lighthammer]

Ok, so cleanup is complete, airbox has been reassembled, van started up, running nicely. Now to take a drive down the highway and see how the performance and smoking have been affected.

[tourniquet]

wow @ the MAF sensor
where did you get the K&N filter from though?
I'm looking at their site and seeing two different styles with different dimensions:
http://www.knfilters.com/air_filter/nissan_navara.aspx
Could it be possible that you ended up with the incorrect filter?

[lighthammer]

I have both the 33-2890 and 33-2080 K&N filters.... one with the horizontally laid filter elements and one with the vertically laid filter elements.

Both of them don't fit properly - one falls into the airbox because it's not big enough to rest on the rim of the box, and the other has to jiggle into place to fit properly.

Neither of them have proper sealing at the edges of the filters, unlike the stock nissan filter.


K&N = bleh, in my book.


BTW, truck rolling real nice and smooth now, good power and torque... hardly any black smoke unless i rev into 3500+ rpm.

[GHOSTRYDER]

that sucks man and i was thinking about getting a K&N for mine

[black start]

You real lucky man....
Had potential to be a lot worst...

[civic minded]

I have the cylindrical k+n filter as opposed to yours Leo and it does form a tight fit, maybe it depends on the application? Mind you i haven't done bonnet height water wading - most i done is up to wheel arches and didnt get water seepage.

[Richard Marshall]

You sure it's original K&N? Or the filter was made for a US manufacture specific Navara? If it is indeed original, and made for the Navara from Thailand sold here, then, K&N isn't to be trusted with some products?. Reason why I asked, I always thought K&N parts to be of high performance and quality. Then again, my brother had an original K&N intake manifold and filter in his car. Performed really well.

[kamakazi]

Now if water got past the seal... How long has the engine been inhaling unfiltered air through the same poor seal. .. Anyone who believes in k&n filters should hold it up to the light and see how big the spaces are.
I stopped using mine a while back and I advise against it having learned my lesson.

[3stagevtec]

The problem here is simply fitment issues.. any improperly sized filter will cause the same issues pointed out.

Are all the locks on the air box working properly? If any are broken, stuff will bypass the filter.

[kamakazi]

K&N air filters on the whole have poor filtration efficiencies when compared to "paper" filter elements.
Besides that most of the k&n drop in filters are made with a reasonably stiff rubber frame that isn't very good at sealing when used in most factory air boxes.
ymmv

[tourniquet]

I think I still have my original filter for my vitara somewhere; if I can find it, I'll try and get a side by side photo of that and the K&N.

[Richard Marshall]

So what's the best air filter out there?

[civic minded]

Manufacturer air filter is the best

[Richard Marshall]

Ok. Cool. But in terms of a modified engine, what then? What's the best aftermarket out there?

[*KRONIK*]

I have k&n in all our vehicles and i cant say i have any fitment issues..

The one in my swift actually has to squeezed in a bit and fits flush into the box.

The filter in my mom's grand vitara is the same...
It fits tightly all around and i never noticed any sealing issues as the locking clips always have a bit of tension from the filter's edge filling the gap

Even in my dad's ford ranger...the cylinder type k&n works just find and fits exactly like the OEM

Now i'm not saying that k&n filters are the "best in the world"
Just saying that one man's bad experience isnt everbody's bad experience...

Some have good stories to tell!

[3stagevtec]

Saw a k&n fit properly in a matrix also.. for off roading use, paper filters are the best, they will filter the finer particles from the air more efficiently.

IMO paper filters can also be washed (gently with mild laungry detergent) and reused.. we still have the factory oem paper filter in use in a mazda b2500 doing 170k+.. paper element in good condition also!

[civic minded]

^^ agreed , paper would be better in high dust and offroading - K&N is really a performance air filter that is made to get maximum air flow. So a better all round air filter for your 4x4 van will be a stock manufacture filter.

[roti102]

Aaaammmm only use K&N if you want dirt in your engine. More airflow means more dirt in.

[lighthammer]

Lol ok I didn't mean to re-start the old "paper vs mesh filter" argument again...


In my own personal case - the issue was poor fitment of the K&N filter into the Navara airbox, versus the stock air filter.

Mind you - better airflow is always a nice thing to have esp. for forced-induction engines....



Just for my own purposes - I won't be using K&N anymore, for exactly the reasons you guys saw in the pics.
Maybe to prove my point I'll go drive the Navara in some waist-height mud and show u guys the difference.... lol.
(anyone have a spare turbo on standby??)

[lighthammer]

Lol ok I didn't mean to re-start the old "paper vs mesh filter" argument again...


In my own personal case - the issue was poor fitment of the K&N filter into the Navara airbox, versus the stock air filter.

Mind you - better airflow is always a nice thing to have esp. for forced-induction engines....



Just for my own purposes - I won't be using K&N anymore, for exactly the reasons you guys saw in the pics.
Maybe to prove my point I'll go drive the Navara in some waist-height mud and show u guys the difference.... lol.
(anyone have a spare turbo on standby??)

[cacasplat3]

my K&N fits perfectly in the navara, on the bike and in the forester....
the rubber seal is soft and i'm pretty sure it does not leak as yours did......maybe you got a bad one....
in all honesty, i'd send a short email to K&N describing your issue.....they have very good customer service......
on a side note, that filter is very dirty...thats about 20,000km without cleaning?

[lighthammer]

my K&N fits perfectly in the navara, on the bike and in the forester....
the rubber seal is soft and i'm pretty sure it does not leak as yours did......maybe you got a bad one....
in all honesty, i'd send a short email to K&N describing your issue.....they have very good customer service......
on a side note, that filter is very dirty...thats about 20,000km without cleaning?

While you may have valid points, and I agree maybe I had a bad one - but the only way to know.... is to bring ur navara and run along with mine

[*$kїđž!™]

guess the manufacturers filter is better......good thread....was gonna get a k&n but this thread changed my mind.....Ill stick with OEM....

[Toyopet]

This is how my engine looked after hitting the mud.


Lower part of the filter box, this mud came in through the stock intake.


Upper part of the filter box, the clean air side.


The MAF sensor, clean as a whistle.


And finally, the hose from the air box to the turbo.


My experience fortunately ended differently but seeing how easy it was for water to get into the intake, I would be taking out the K&N before i hit the next trail for sure. I think what saved me was the fact that it was already dirty so the spaces would have closed up.

[sliderz1]

you checked your intercooler dude?

[3stagevtec]

There was a time I saw a Ford Ranger air box fill with muddy water while off roading. Owner had in his original filter, but he had a leak in his fender shielding and while revving in a mud pit, the front tyre threw muddy water up into the factory intake inside the fender. That muddy water worked it's way into the air box, it plugged the water drain inside and the air box filled just up to the 'airbox to turbo' line.

While doing so, the inlet to the airbox got completely blocked off by the muddy water and the motor got suffocated. It had lost all power and cut off. I had to praise the design of the Ford airbox in this case because if the 'airbox to turbo' line was located any lower, the turbo would have drank water.. or worse, it could have reached the motor!

When off roading, you must look at the full intake system from start to finish to ensure it can handle deep water crossings. That way, your engine can look like this and still be clean inside! lol

[3stagevtec]

you checked your intercooler dude?

If no water reached his turbo, his intercooler should be clean also..