Oil in air box?

[KentuckyHonda11]

Can someone help me understand what I'm looking at here? I was installing Oxford heated grips on my NT (great idea, btw, if you haven't done that, you should), and a new USB charging port, so I had most of the tupperware off. I've only had the bike a couple of months so I figured why not lift the tank and check out the air filter? (Toothless has 16.5k-ish on her, fwiw). I finally get the air box open after realizing there is a center screw, and see this oil in the bottom of the box.

Seems a bit pooled where the K&N filter sits, and then a trail back to the smaller rear compartment within the air box, whose purpose I don't even know. The seal on the rear part of the air box had this oil in it, too.

Do the NTs have a PCV valve? If so, is this related to that somehow? I'm assuming oil sitting around in the air box isn't good, but more than cleaning it out, I want to make sure something more nefarious isn't going on.

 

[RedLdr1]

Sounds like someone over oiled the K&N filter. The old "if some is good more is better" mentality at work. I see that all the time with Mustangs... I'd clean out the air box and toss the K&N for a new regular paper air filter.

 

[KentuckyHonda11]

I'd honestly be shocked if that were the case - the guy I bought the bike from is like an uncle to me, who is meticulous about all of his vehicles and does nothing not according to spec. Also it smells like motor oil to me, but I'm no professional.

 

[Macka]

A small amount of oil mist in the smaller compartnent is normal. That is the purpose of it. If it has leaked into the main air box, the seal is insufficient. Look at the sealing faces and if you think you need to you could apply a very small amount of Non Hardening sealant around the lip.

Macka

 

[NewTo700V]

As Macka said, a bit of oil residue in the airbox is a normal occurrence. That little tub molded into the airbox shown in the first photo has a crankcase breather hose attached to it. So what you're looking at is a tiny bit of blow-by. Simply having the oil topped off a bit more than ideal can cause oil to puke up. Honda anticipates a bit of stuff getting up there on occasion, so they put that tub there to try and collect the more liquid stuff so it can drain back down.

Now if there's actually like a cup of oil in the airbox, that could be a more serious issue like worn rings. However, at 16K miles I doubt any of those things are going on.

 

[KentuckyHonda11]

A small amount of oil mist in the smaller compartnent is normal. That is the purpose of it. If it has leaked into the main air box, the seal is insufficient. Look at the sealing faces and if you think you need to you could apply a very small amount of Non Hardening sealant around the lip.

Macka

Thanks! Looking at the pictures I posted and another couple I took, I don't think there is any sort of offical "seal" there between the two boxes - just the overlapping plastic pieces of the base and the lid.

 

[Macka]

Correct, there is no seal as such. That is why I suggested you use a small amount of non hardening sealant. It is not critical that it does not seal 100%.

Macka

 

[NewTo700V]

You don't want any seal. The air box needs to be able to pull fumes emanating from that little tub to bring back into combustion. Restrict that you could risk high crankcase pressure. Would be the same thing as putting a kink in the breather hose

 

[KentuckyHonda11]

You don't want any seal. The air box needs to be able to pull fumes emanating from that little tub to bring back into combustion. Restrict that you could risk high crankcase pressure. Would be the same thing as putting a kink in the breather hose

well thanks! That sounds...bad