Curious About Dirt Pattern On Used Filter

[Virtus_Probi]

Just did my own air filter for the first time, have had some OEM replacements (and some FRAM I bought for no good reason) on hand since I started doing my own oil at 15k but I think the dealer replaced one for me at my 30k (non-oil) service. I am getting fairly close to my 45k oil change and decided to do the air filter last night after cracking the box open and seeing that it looked fairly dirty...I had a surprisingly hard time getting the box back together after putting the new filter in, but no biggie.
I was surprised about how the old filter looked...it was dirty on the left side as I was pulling it out, but the right side still looked fairly clean EXCEPT for some mashed up leaves that were jammed into it. The clean area was bigger than just the part with the leaves, though, so I don't think disturbed airflow from those was the sole reason for the clean area.
Seems odd to me that the air intake would be designed to make use of only a portion of the air filter's area, so I'm wondering if more leaves or other things might be blocking part of the intake. Before I get in and start really messing with this, anybody else noticed odd dirt patterns on their used air filters and anybody know if this is really something to worry about?

 

[SatinSilver]

Yes, you're supposed to rotate the air filter.

Joking of course but I've noticed the same exact thing with the last few cars I've owned. The round air inlet tube is right by the dirty part of the filter, so completely normal.

 

[Yah-Tah-Hey]

My Camry V6 has two sources of air supplying the filter inlet box. Your engine may have a similar arrangement.

 

[MNgopher]

Its normal. On my Explorer, it has a long rectangular filter. The end where the fresh air inlet is is always substantially dirtier than the other end. If the filter ever were to clog up enough, it would just pull the air through the less dirty section - path of least resistance...

 

[HTSS_TR]

It's very normal. There isn't a perfect air intake to let air flows evenly across the air filter.

 

[SZR48207]

Originally Posted By: HTSS_TR
It's very normal. There isn't a perfect air intake to let air flows evenly across the air filter.


On my old F150 the filter design was pretty good about even wear at least in terms of making use of the area around. Lengthwise was probably a challenge. It had a conical type of filter and the air passed over the narrow nose and through the filter media.

But yeah OP the rule here is that air will follow the path of least resistance.

 

[rrounds]

Originally Posted By: HTSS_TR
It's very normal. There isn't a perfect air intake to let air flows evenly across the air filter.

I don't know, our S2000 filter housing is very good at getting air to all the filter. I have over 90k miles on mine now and I'm going to change it out because of time not restriction. I will take pic's when I do change it out, won't be to long.

ROD

 

[HTSS_TR]

Originally Posted By: rrounds
Originally Posted By: HTSS_TR
It's very normal. There isn't a perfect air intake to let air flows evenly across the air filter.

I don't know, our S2000 filter housing is very good at getting air to all the filter. I have over 90k miles on mine now and I'm going to change it out because of time not restriction. I will take pic's when I do change it out, won't be to long.

ROD

I changed the filter in my S2000 5-6 months ago, the top 2/3 was much dirtier than the bottom 1/3.

The flat filters in E430 and V70 weren't evenly dirty either, the 1/2 area near the intake tube was much dirtier.

 

[DoubleWasp]

Dirt isn't terribly good at taking right-angles. Wherever it comes in is where it will impact, generally.

 

[Virtus_Probi]

Originally Posted By: SatinSilver
Yes, you're supposed to rotate the air filter.

Joking of course but I've noticed the same exact thing with the last few cars I've owned. The round air inlet tube is right by the dirty part of the filter, so completely normal.


You know, if it wasn't for the leaves, that might have made sense for me!
;^)
Thanks to everybody for their thoughts, it all makes sense and it sounds like I don't have a problem. I will still take a little time this weekend to study how the intake works and make sure I don't have more leaves/whatever in there, if I can...even with my shop light, it was too dim in the garage to see the whole system well enough for me to be sure I knew what was going on while I was actually changing the filter.

 

[razel]

Yup normal. Feel free to rotate it 180 degrees clockwise or counter clockwise. I do. Also don't clean the filter. Remove the obvious big debris and shake it but as for blowing it with air, which two of my Toyota service manuals say to do so, I don't. I just replace if it's that's bad.

 

[DoubleWasp]

Believe it or not, rotating my filter so that th side of the pleats face the air opening has reduced the level of my filter minder restriction. Might be that with the side of the pleat blocking the intake opening, there's greater disturbance of airflow.

 

[Duffyjr]

Originally Posted By: DoubleWasp
Dirt isn't terribly good at taking right-angles. Wherever it comes in is where it will impact, generally.


You can really see this with the old round style filters. There is always a little round circle of dirt right where the inlet is. I turn it 1/4 turn a couple times a year when my oil gets changed.

 

[CT8]

Originally Posted By: DoubleWasp
Dirt isn't terribly good at taking right-angles. Wherever it comes in is where it will impact, generally.
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