Air filter hole

[Lou Wambsganss]

I searched the forum, and the innerwebs in general, and could not find an explanation for the hole in the air filter. My OEM filter has it, and all the pics I could find of aftermarket filters have it also.

I have two theories:

1. It is a moisture drain so that small amounts of water sucked in the inlet can bypass the filter media.

2. It is an air bypass so that if the paper media becomes completely clogged, there will still be a small amount of bypass airflow to keep the engine running.


I guess it's OK, since all of the filters have it, but I'm a little uncomfortable with the idea of unfiltered are bypassing into the engine.

 

[maxwellian]

I'm guessing condensation drain. The top arrow is the airbox, and the bottom the air box lid, right?

Doesn't that hole go right to the outside? So that any condensation on the airbox lid drains out?

The air flows down through the filter, not up, right?

 

[Lou Wambsganss]

I'm guessing condensation drain. The top arrow is the airbox, and the bottom the air box lid, right?

Doesn't that hole go right to the outside? So that any condensation on the airbox lid drains out?

The air flows down through the filter, not up, right?

I think you are right. Upon closer inspection, it looks like the upper and lower airbox gaskets don't follow the same path. The upper half goes around the outside of the hole, but the bottom half stays inside. This means that it simply vents the upper half, which is already unfiltered air anyway.

Well, now I feel dumb, but better having a believable answer...