Poorly-fitting K&N replacement filter ...

If you have a replacement K&N filter that seems to not fit your XJ, this thread is for you.

I have a '91 XJ sport with the 4.0 HO motor. I put in a replacement K&N filter, and noticed its a little too short in length and width -- about 1/8" on each dimension.

So ... I did a little looking into it.

K&N lists two different air filters for XJs with the 4.0 motor:

For 87-96, they list part number 33-2018.
Height: 1.625 in (41 mm)
Outside Length: 13.438 in (341 mm)
Outside Width: 6.625 in (168 mm)

For 97+ 4.0, they list part number 33-2112
Height: 1.125 in (29 mm)
Outside Length: 13.75 in (349 mm)
Outside Width: 6.875 in (175 mm)

Notice that the later-year model is larger ... but not as deep, which means it will have less pleat depth, and less surface area.

Now ... get this: I called the dealership, and they list only one air filter for all 4.0 XJs ... Part number 53004383. Same is true for Fram and Purolator. They all make no distinction between pre-97 and 97+.

And ... when you do a cross reference check on the K&N website: http://www.knfilters.com, type in the jeep or the Fram or the Purolator PN and you'll get both of the K&N part numbers above, even though the air box is the same on both year ranges.

So ... I think that K&N has made some sort of mistake. My air filter is definitely too small, and others with pre-97 XJs have said the same thing. I'm sure the K&N part number 33-2112 would fit my '91, even though it's listed for 97+.

I called K&N about this, and you should call too ... this should be handled as a warranty issue.

Here is their phone number: (800) 858-3333

The guy I talked to asked me for my VIN, Airbox part number, and photos (optional) of the air filter not fitting properly. I emailed him with all that, and I'm still waiting for the guy to call me back after his lunch break.

But ... the more people that call, the better results we'll get.

I'm surprised to hear that. I've never heard a bad thing about a K&N air filter.

I would definitely think twice before installing one on a Jeep however. They do allow more dust and dirt into the engine than a standard paper filter. Is the possibility of an additional 1hp or 1 mpg really worth it?

anony91xj said:

I would definitely think twice before installing one on a Jeep however. They do allow more dust and dirt into the engine than a standard paper filter.

Click to expand...

That's true ... I didn't know that until after I bought it. The guy on the phone gave me a return authorization number, and I'll be returning it for a refund.

I'll probably just go with air filters from now on.

montanaman said:

That's true ... I didn't know that until after I bought it. The guy on the phone gave me a return authorization number, and I'll be returning it for a refund.

I'll probably just go with air filters from now on.

Click to expand...

Yeah, if you're driving a performance car K&N filters can be great (unless it's a mass-air system and the filter is over-oiled, but that's another issue). I'm not sure I like the idea of one on a vehicle that sees wheeling conditions though...I stick with paper filters in my Jeep for that reason.

This has been known for several years, and it's disappointing that K&N hasn't seen fit to correct the problem.

Conventional wisdom was that the K&N for a Dodge Dakota (I think it was the Dakota) fits better than the one for a Jeep. Try searching OLD posts (going back at least 2 or 3 years) and you may find the part number.

anony91xj said:

I'm surprised to hear that. I've never heard a bad thing about a K&N air filter.

I would definitely think twice before installing one on a Jeep however. They do allow more dust and dirt into the engine than a standard paper filter. Is the possibility of an additional 1hp or 1 mpg really worth it?

Click to expand...

Just because they cost 4 times more than a good stock filter don't make them better.