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-   -   DIY: K&N Filter Cleaning (https://www.team-bhp.com/forum/diy-do-yourself/265767-diy-k-n-filter-cleaning.html)

As a sequel to post#131, I ended up cleaning my K&N filter again, this time after 12,000km; procedure and stuff used to clean and oil the filter were the same as in my earlier post.

Observations

1. The filter was more fouled up at the top half of the filter towards the tapered edge
2. A lot of dirt was trapped - showed up in the number of washes/rinses during cleaning

Progress

MAF Sensor after 12,000km


The "clean" (outlet) side of the dirty filter


The dirty inlet side of the dirty filter - note more clogging towards the taper end




Dirty filter inlet side against light






Rinse water after rounds 4, 5, 6, 7 in that order (forgot to click pics of Rounds 1 to 3)






Clean water at end of round7


Oiling the filter after leaving it to naturally dry for over 24 hours - extra time since sun was playing hide and seek:)


Clean filter against light


Before vs After - at the same place against same light


Summing it up

1. Based on driving conditions, the filter would need cleaning anywhere between 12,000 and 20,000kms.The first tell tale sign is a drop in pick up and an increase in fuel consumption
2. Personally, I think I did a more thorough job this time than last time. The filter wicks showed so.
3. The process of cleaning and oiling is quite a pain - takes close to 1.5 hours to clean, overnight to 24 hours to dry, and another about an hour to oil. But this task forces one to squat, and helps in getting one's joints oiled. :)

While K&N recommends cleaning/servicing the filter every 50k miles as its supposed to filter better the dirtier it gets but for our dusty environment 20k kms is a good service interval or earlier depending in any performance or fuel efficiency drop. And this is for the factory box replacement filter and not the conical filter which I personally feel is a waste if your car is a daily driver. For track use the added performance does help.

I use the K&N cleaner and spray it and leave it for a few minutes and then hose it down and repeat the same procedure once again and then oil it in two rounds (ensure not to put too much oil as that will mess up your fuel injector’s). This schedule and process has been working well for the filter on the Brio.

I did the same a few months back as well...while K&N assures a lifetime working filter for dusty conditions like ours it needs to be cleaned regularly.

K&N Filter Cleaning

K&N recommendations are US centric where environment is relatively dust free. I used to have K&N way back on my Ikon. For most part it gave a bump in mental BHP rl: but did make the engine sound tad better at higher RPMs. I used to self clean it every 10K when rest of service used to be done. But you are right, it can go easily 20K without getting clogged.

Exactly my sentiments. I used to have K&N way back for My Opel Astra Club and yes it used to reach the 6500 RPM pretty quick coupled with slight increase in BHP. I bought the K&N filter along with that servicing kit from Reliance Autozone in Gurugram. I used to clean it every 5000KM.

I cleaned (using mild bath soap solution) and oiled (using K&N oil) my BMC which is similar in design to K&N filter approximately 20000Kms ago and it does not look like it needs another cleaning and re-oiling anytime soon. I inspect the filter occasionally and check for any dust on the clean side of the airbox which I find none. Let me see how long I can stretch the next cleaning and re-oiling session before it starts to affect performance and efficiency.

Prior to this I have, in other vehicles, used K&N/BMC and used to periodically clean it at 10000Km intervals or earlier. But it seemed like a wasted effort (and oil) as there was no perceptible difference between a clean and dirty air filter.

Another observation I have made regarding K&N or similar airfilters and small naturally aspirated petrol engines is that they seem to work better on cars with MAF (manifold air flow) sensors rather than on cars with speed density airflow calculation method. In a MAF based system the engine ECU use MAF sensor to directly measure the airflow into the engine and adjust fueling accordingly. Whereas in a speed density system the engine ECU uses MAP (manifold air pressure) sensor, IAT (intake air temperature) sensor and engine RPM to indirectly calculate airflow into the engine and adjust fueling based on that. On carburetted engines K&N and similar filters works very well if the carburettor is re-jetted suitably.

Apart from the engine air filter, I also use a K&N cabin filter. Its a cotton mesh filter just like the engine air filter and can be cleaned using mild soap solution. But it should not be oiled and instead needs an electrostatic filter spray to be applied after cleaning and drying.

One important point regarding all cotton mesh air filters - Do not use pressurised air to blow clean the filter. It will damage the filter media. I have seen one workshop do this, its wrong.

Great thread! Reminds me of my student days in the USA when I used to clean my pre-owned Accord's K&N myself :).

Depends which one. The stock replacement filters, maybe. But the car-specific ones do bring some gains. I got the Typhoon for my Civic and took it to the dyno - link.

As you rightly said, the intake sound too. Man, it sounded sweet when revving :thumbs up.