Slight oil residue on air filter, is this a broblem?

[BigJoe]

I am doing an engine service and noticed a slight oil residue on the bottom of the air filter, is this a problem.

Yanmar 4JH4-TE, I haven't noticed any drop in oil level.

Thanks.

Joe.

 

[Jamie Dundee]

I get the same, my crankcase breather feeds into the air filter. Perhaps yours is similar.

 

[alancollins]

My Volvo is the same.

 

[Yngmar]

On our MD22 the PCV breather also goes to the air intake, and when the PCV valve that regulates the crankcase breathing got stuck, there was enough oil on the bottom of the air filter for it to drip down from there. However, it also came with a drop in oil level.

If your ventilation system is similar, I'd say it's not unusual to have slight residue. Only if there's enough to drip and you do notice the oil level going down, check the breather valve. Ours was clogged up with oily crud.

 

[BigJoe]

I get the same, my crankcase breather feeds into the air filter. Perhaps yours is similar.

Yes, so hopefully nothing major.