Air filter was black with sooty oily residue

[HK_Ace]

So I changed the air filter on my Subaru Forester yesterday. I noticed it was in bad shape with an oval section of it (maybe 30%-40% of it) covered in this soot-like black grime. It was almost oily but just slightly. The filter definitely needed to be replaced.

This has never happened before and has me a bit concerned, though the last oil change and all that was done at a shop. They may have opened the filter box to take a peek and maybe not reinstalled it perfectly? Normally, the filter will have more dry residue/dirt stuck in it; not this slightly oily black grime.

Any thoughts on this and should I be worried about anything?

 

[Billbert]

Replace the PCV valve & clean the hoses to it.

 

[EricF]

check your pcv valve and make sure it's in good shape.

 

[sunfire]

I believe that oil is coming from the engine and from the PCV. That can happen to filters that haven't been changed in a long time.

 

[Soobs]

What year is your Subaru and what's the mileage?

Sounds like you're getting some oil blow-back from a stuck or gummed-up PCV valve. Replace the PCV valve (best to stick with an OEM replacement) and you could clean the hose for it like someone suggested or just buy a new hose. Both the valve and hose are cheap. Might want to clean out the air intake compartment and hoses too.

If your engine is how mileage and you've notice an abnormal loss in oil between changes you may see the problem come up rather quickly again though.

 

[HK_Ace]

It's a 2006 with around 71,000 miles. I'll look into this stuff and also keep an eye on my oil consumption.

Is this PCV valve pretty complex stuff a shop needs to do?

 

[HTSS_TR]

PCV valve is very easy to change, easier than oil filter, it's usually on top of the valve cover. Most OEM PCV valves cost less than $10, or you can buy a Fram PCV valve at auto parts store for around $3-4.

 

[widman]

I'll second everything said, but it also might be more driving in city/smog/etc. As I showed on another post about the restriction gauges, some seasons can shorten a filter life by 50%.

 

[HK_Ace]

I have parked the Forester till I figure this out and for another reason I'd rather not share.

I am driving the 4Runner. One thing I did not make clear or mention is that the oily black residue was on the underside or fresh-air side of the filter. Would oil blowback not coat the opposite side? I drive mostly highway but sometimes, there is fresh asphalt here and there due to fixing roads before winter...not sure if that matters.

 

[HTSS_TR]

Did you buy this air filter at a Subaru dealer ? Many Japanese air filter are now lightly oiled therefore you will see "soot-like black grime". It's the same with my '04 S2000 with OEM air filter.

 

[HK_Ace]

Yeah, it is a Subaru filter. The new one seemed to be totally dry though. As soon as I siphon some coolant out, I'll drive it and see if the same issue surfaces.

 

[Soobs]

Originally Posted By: HK_Ace
One thing I did not make clear or mention is that the oily black residue was on the underside or fresh-air side of the filter. Would oil blowback not coat the opposite side? I drive mostly highway but sometimes, there is fresh asphalt here and there due to fixing roads before winter...not sure if that matters.


Oh, well... might not need a PCV valve... What you're seeing may be normal if you haven't changed the filter in a long time (or ever). It would help if you posted a picture of it, but I bet you just ran the filter too long. No big deal, so long as you change it now. And by the way, nothing fits and seals the airbox as well as a Subaru OEM air filter.

 

[HK_Ace]

Too late for pic- trash pickup happened. Maybe I just left it too long. I'll keep checking it more frequently...this gave me a scare. Thanks guys!