Author Topic: Paper Air Filter - Does it matter which way it goes? (Read 4565 times)

Zu! · « **on:** November 07, 2007, 08:07:16 pm »

Hello:

I've been experiencing some intermittent black smoke these past few days. At first, I thought it was some gunk in the fuel, cos it only seemed to happen near the end of a tank. But lately its been happening just about anytime! Big puffs of smoke even when idling and especially in slow traffic.

So I did a search of the forums and came up with the air filter being dirty. Opened it up and lo and behold, was it ever black!

So off to the local Cndn Tire I went, they had two types for my 91 Jetta TD. One was 1 5/8ths inches thick and the other was 2 inches. Checked what was on the car (that the PO must've put in) and it was the thick one. So I stuck it in just now. Reading through the Bentley though, it clearly mentioned that for gasoline cars, the filter goes in with the gasket on top (fins of filter facing down). And for diesels, the filter's supposed to go in with gasket facing down (fins of filter facing up!)

However, try as I might, I could not get it to fit. So now, I've got the new filter in, with the gasket facing UP (fins facing down), which when I think about it, doesn't seem right, as the air is coming from below right? So my fins should be up (gasket down)...geez, I hope I'm not confusing anyone :oops:

Anyway, should I change the filter to the thinner one? It seems that the filter probably wont work right if the airflow is going the wrong way right? What do you think? Thanks!

Zulfiqar · « **Reply #1 on:** November 08, 2007, 02:17:27 am »

fins should face upwards - fiting it the opposite way would make its life like waaaaaaaaaaaaaay shorter.

the fins provide a larger catching area for dust, large catching area = more flow

and then it also does a great job of silencing the intake roar when its fit the right way

Zu! · « **Reply #2 on:** November 08, 2007, 06:40:43 am »

Yikes...so that means I bought the wrong one (and the PO probably did that too) as there's no way I can fit it into the box with the fins facing upwards as the filter is waaay too thick. I wonder if Cndn Tire will take the filter back if its one day old :roll:

Thanks for the tip bud!

burn_your_money · « **Reply #3 on:** November 08, 2007, 09:41:11 am »

Do you have a TD or a NA?

No TDs the fins should be pointed down

On NAs they should be up

Zu! · « **Reply #4 on:** November 08, 2007, 11:30:21 am »

Hi...I have a 1991 Jetta Turbodiesel. What's confusing me is Bentley saying the the gasket has to face down. But with the thick filter I got (2 inches vs the other one at 1 5/8ths) there's no way I can fit it with the gasket down (fins up).

Why the difference? I mean the air is coming from the same place no? :?

burn_your_money · « **Reply #5 on:** November 08, 2007, 11:36:41 am »

On a NA the air is coming in the top of the box, on a TD it is coming in the bottom.

Here's some pictures of a TD box

Zu! · « **Reply #6 on:** November 08, 2007, 12:28:02 pm »

Great! So I got it right then! That's exactly how my TD airbox looks and also exactly how my filter appears to fit in there. Thanks Tyler, that's really reassuring to know!

Its interesting though that since the air comes in from the bottom that the fins would point down. I would think that fins up would catch more dirt as the dirty air would then be forced into the slots and forced through the paper in those slots.

Well, whatever, thanks again!