Incredible Shrinking K+N Filter

[Rasputin]

Does anyone know why a K+N filter would shrink in size? I have one here that a fellow member sent me. It is considerably smaller than a new one.
Do not get me wrong as there is no complaint against that member. Just wondering why K+N filter would shrink in size.
Part numbers are the same on both. I tried to clean the shrunken one but it would never come really clean. When the K+N oil was applied it would not look any better than if you simply oiled it with motor oil.
I ran myself out of the K+N filter cleaning fluid and their oil trying to get this filter to look red like they are supposed to look.
Just for giggles I am going to post some pics of the filters in question. The one I received is a full half inch shorter than a brand new one. It is also shorter in stature than a new one. It will not clean and oil like a K+N is supposed too. It also is quite a bit more inflexible than the new one is...Maybe a clue.

[jetmechmarty]

I just lifted this from another forum. It won't make your filter grow, but I expect it will get it clean.

Cleaning a K&N air filter for re-use
Cleaning a K&N air filter for re-use.....
Get a small air filter size bucket... dump two scoops of Oxy powder in it. Then place the air filter in there..... pour 1 1/2 2 liter bottles of generic club soda in the bucket.....about 3 litres total...depending on the bucket you use...a smaller bucket uses less club soda etc...

It bubbles and foams up almost Instantly as a greasy dirty film and tons of dirt and crap jumps out of the filter gauze. The foam's all topped with yellow filter oil & dirt, grime and bug stuff...it's amazing that all that stuff was still in there after having cleaned the filter three times the "normal" way. The club soda is the trick. The carbonation 'boils' the crap out of the filter's gauze fibers instantly.

Use a piece of paper to scoop out the nasty oily grime & dirt that's riding on top of the foam in the bucket and toss the paper away so you don't have to lift the filter up/out thru that stuff.... swirl the filter around in the solution for about 3-4 minutes and let it sit for a minute or so.....finally shake it in the solution for a few seconds and pull it out...elapsed time about 10 minutes.

This is much better than blasting it with water trying to rinse the crap out or blowing it out with an air hose.

let it dry really good, oil the filter up and reinstall it.... some people have two filters so they can keep one oiled, clean, and plastic bagged, do a speed swap and then take their time cleaning, drying and oiling up the other one.

[Rasputin]

While that may make the filter clean I am still wondering what makes it shrink, Heat maybe or a wrong cleaner or what. Puzzles the hell out of me!

[natemoen]

I had one like that too. Same thing, bought it from another members parts bike surplus and when I got it, it was way to small but was the correct number.

I emailed k&n and they sent a new one no questions asked (well I guess they did ask the milage of the bike).

They stand by their warranty!

[jetmechmarty]

While that may make the filter clean I am still wondering what makes it shrink, Heat maybe or a wrong cleaner or what. Puzzles the hell out of me!

Do you think maybe an airbox full of gasoline could do that? I found this on the internet, so it must be true.

The explanation is solvent gain/loss. Rubber swells or shrinks when it gains or loses interstitial solvent. A new piece of rubber contains a certain amount of solvent from the manufacturing process. Lose some solvent through heat and age and the rubber will "shrink". Gain some solvent through contact with certain hydrocarbon mixtures (like gasoline/additives blends) and the rubber will "swell".

If the above is true, you might have luck with a mineral oil soak.

Never mind. After reading Nate's post, trade it for a new one.

[Shacknasty]

I had to get a new filter also. I opened my airbox to find that, after about 10 years, the filter had shrunk and would no longer fit the airbox properly. I thought I lost my mind. Glad to see someone else had the same problem. It appears I have not lost my tenuous hold on sanity...

[clcorbin]

Chinese knock off? I have a hard time believing a genuine filter could shrink that much. Especially given that there is a metal screen supporting the filter media. But who knows.

[jwhughes3]

This is directly off the K&N website:

"Engine oil in the air box, resulting from excessive blow-by, will cause the filter to shrink and possibly lose its seal."

http://www.knfilters.com/filter_facts.htm


John

[GLoweVA]

Just to add, I've had one shrink too. It was a real pita to get the airbox back together.

[CaptonZap]

This is directly off the K&N website:

"Engine oil in the air box, resulting from excessive blow-by, will cause the filter to shrink and possibly lose its seal."

http://www.knfilters.com/filter_facts.htm


John

Howdy John,
Do you know if K&N will replace them even if they have been "oiled"?
The latest project bike has a shrunken K&N.
I find it odd that they would use an elastomer that was not compatable with engine oil. Since they should know that us cheap skates will use it to oil the media.
Thanks for the URL.

CZ

[Cuda 69]

doesn't kn cleaning kit contain spray oil for filter?

[mikubuilder]

it happened to me too(shrink and loose color)...it's because of gas in the air box, I'm absolutely sure of it...

[natemoen]

Howdy John,
Do you know if K&N will replace them even if they have been "oiled"?
The latest project bike has a shrunken K&N.
I find it odd that they would use an elastomer that was not compatable with engine oil. Since they should know that us cheap skates will use it to oil the media.
Thanks for the URL.

CZ

Like I said, they sent me a new filter, no questions asked. They didn't even ask for me to return the bad filter to them.......the first time.

[clcorbin]

Learn something new every day!

[Rasputin]

Thanks Natemoen I will look into that. It is entirely unusable in its present condition short of grinding off the tabs where it mounts and making something of my own. Funny they did not require you to send it back. Hell it could be sold several times over without them getting the faulty one back.