Oil, lots of oil, in my airbox (Now I know why)

[stopintime]

Here we go again  

I asked God and Stuart, but since none of them answered - this is for you..

Half a quart of oil ~ in my airbox  

No pictures, but looking at traces it's obvious that it comes from the crank house.
From the airbox 'pouring' into the lowest intake (vertical cylinder), especially in left turns, resulting in stuttering and white smoke.

Ideas? I have one myself, but I'd like you to think about this without evaluating my thoughts


The situation:
Top speed run through a tunnel
Roll off throttle
Stuttering
Another 50 miles less and less stuttering
Some stuttering after left hand turns

Stopped outside my dealer
Oil dripping out of the exhaust
Vertical spark plug wet (oil) Horizontal dry.
No scary noise or vibration
No oil pressure light

[ducpainter]

Has to be a breather problem...

or bad rings pressurizing the cases.

[Speeddog]

Essentially agree with DP's thoughts.

What is the oil level in the engine now?
Perhaps overfilled, and between the lines now?
Or low, now?

[koko64]

Same thoughts as above guys. Hopefully only over filled.

[stopintime]

Was at max line.
Is well below min line.

I have overfilled by accident before - no such symptoms then.

This was a sudden event - I assume caused by a specific malfunction.

Can bad/broken rings increase the crank house pressure? In such a violent way?

[ungeheuer]

I have nothing sensible to add Lars 

Just wanted to say... sorry to read this mate.

If it's just the breather it shouldn't be too $$ to resolve?  I'll hope for that.

PS:  Its "crank case", but we forgive you.

[Howie]

Yes, blow by from worn rings will cause this, but I suspect you have a problem in the breather, maybe a read valve that is broken or held open from sludge.  As stated, overfull crankcase is a possibility too.

[ducpainter]

Was at max line.
Is well below min line.

I have overfilled by accident before - no such symptoms then.

This was a sudden event - I assume caused by a specific malfunction.

Can bad/broken rings increase the crank house pressure? In such a violent way?

Bad rings could cause it, but I think they'd have to be so bad you would see some other symptom like plug fouling or pretty poor running.

If it is rings, a simple compression test will easily detect which cylinder has the problem.

[stopintime]

PS:  Its "crank case", but we forgive you.

Crack house is the correct term  

Yes, blow by from worn rings will cause this, but I suspect you have a problem in the breather, maybe a read valve that is broken or held open from sludge.  As stated, overfull crankcase is a possibility too.

If it's open all the time - wouldn't that normally just cause a little vapor - not enough to fill the breather and then the airbox?

Exhaust comes off for cleaning - maybe time for new packing as well.
Heads and cylinders off to be inspected.
Breather valve will be checked.

Bad rings could cause it, but I think they'd have to be so bad you would see some other symptom like plug fouling or pretty poor running.

If it is rings, a simple compression test will easily detect which cylinder has the problem.

Everything was fine until the tunnel run - no bad ring symptoms, so I can only assume that something dramatic happened then and there.

[ducpainter]

Other than drooling oil from the exhaust...how did it run when it wasn't trying to overcome the effects of dumping oil into the intake?

[stopintime]

Other than drooling oil from the exhaust...how did it run when it wasn't trying to overcome the effects of dumping oil into the intake?

Quite well, but I didn't push or rev it much, so it might have been working poorly on one cylinder.

[Howie]

If it's open all the time - wouldn't that normally just cause a little vapor - not enough to fill the breather and then the airbox?

Hard to say, on our twins there is always positive pressure in the crankcase and there is some vacuum in the air box.  Vapor also does eventually become liquid.  I should have asked, air box open or closed?  More likely with a closed air box since more vacuum will be present.  Add a little overfull, some hard riding and maybe some normal engine wear.

As Nate said, a compression test, or even better, a cylinder leakage test will determine cylinder condition. 

[monsta]

Everything was fine until the tunnel run - no bad ring symptoms, so I can only assume that something dramatic happened then and there.

I'd have to agree,  lots of oil in a short time, cant be good...  I'd be thinking the worst, sorry to say...

[stopintime]

I'd have to agree,  lots of oil in a short time, cant be good...  I'd be thinking the worst, sorry to say...

Worse than piston rings?

[Howie]

Diagnosis is your friend, and always start with cheap, easy first.  Compression/leak down test and breather inspection first.  Compression good?  Rings are not your problem.  Worst case scenario?  Nikosil failure.You wouldn't find that until a tear down.  No reason for a tear down if compression is good.

The air box would not load up with oil quickly from a defective breather, but you would not spot the problem until you encountered a running problem or you looked in the air box.