Blow by and compression

[alaskan99669]

I don't think it would be too hard. I'm thinking maybe you could simply clamp a small needle nosed vise grip to the pipe and take it for a few laps around the pattern.
I'm at work now, but I believe the inside of my pipes are pretty much black, but don't hold me to that.

[DWood]

I know it is going out the exhaust because I find it on my flying wires when on floats.

Just curious:
What are you finding on your wires; is it oil (liquid) or carbon? Are you checking leak down with the engine at normal operating temp?

[alaskan99669]

It's oil (in a nasty, greasy form). Leak check tested after pushing in hangar, removing cowling, etc., etc., so at room temp by the time we get to the actual test.

[DWood]

I would doubt that if it is raw oil that it is coming from the exhaust. Bruce mentioned that when his oil level gets to around 5 quarts, it seems to stop blowing (Bruce I am paraphasing so please correct if I am wrong). I personally run my 170 between 5 to 5.5 indicated on the stick as it seems to greatly reduce oil consumption. If I am flying for several hours, I might put it at 6 but never more.
Dan

[alaskan99669]

I would doubt that if it is raw oil that it is coming from the exhaust...
Dan

Look at my picture again on Page 3. It is barely noticeable in the picture, but believe me, just downwind of the right exhaust pipe outlet is a significant deposit of oil on my flying wire that absolutely has to be coming from the exhaust pipe. I have not investigated why there is not as much a deposit on the left side. Either that side is not exhausting as much oil or it is not as aligned with the flying wire.

[GAHorn]

... I have not investigated why there is not as much a deposit on the left side. Either that side is not exhausting as much oil or it is not as aligned with the flying wire.

Your crankcase vent is on the right-side and your prop-blast swirl may have something to do with it. (The angle of the wires on the right side is more likely to catch contaminates than the angle of the wires on the left.)
Exhaust products mixed with oil (from a different source) is a more likely scenario than liquid oil exiting exhaust pipes.

[Bruce Fenstermacher]

Dan, you have my observation from my last flight correct. At about 5 quarts the engine seemed to stop pushing oil out the vent tube. This is based on two legs totaling 1.4 hours.

With 8 quarts being full I never felt 5 quarts was where I wanted to run the oil level. Like I said had I had a quart of oil I'd have put it in. I would not start a flight with less than 6 quarts. Had it been summer when oil temps get right to the limit I would have found a quart somewhere. Of course I have an oil filter so I probably have about a half quart more oil in the engine than shows on the dip stick.

Though 5 quarts is higher than the minimun oil level I've been of the opinion that the more oil there is the better it will be for cooling purposes and also the higher oil volume should be able to carry more contaminants before loosing effectiveness. I have no proof my opinion has any validity.

I'll be changing oil in a few days from straight 50 weight I run in the summer to Phillips 20-50 for the winter. I'll probably put in 6 quarts as measured on the dip stick and run it and see what happens. I'll let it run down past 5 quarts and keep tabs to see if in fact the usage does level off. Don't know if changing to the multi grade will effect any of this in any way.

[alaskan99669]

I wouldn't think it is from the crankcase vent as that is still within the cowling and would end up on the belly of the plane. The oil on the flying wire is in a direct path of the the left exhaust as if it where a shotgun barrel that points at the wire. The deposit is a significant layer of oil that is about 2" - 3" wide directly inline with the exhaust pipe. This accumulates during the 25 - 35 hours I put on the plane during float season.

[DWood]

Bruce:
When I change oil, I put 6 quarts in and it reads around 5.5 on the stick. It seems that when I put more in, it just goes away. As far as multigrade oil, I am not a supporter due to issues with Champ I once owned, The previous owner used multi grade so I stayed with it. However, in the summer, I would get it on the windshield from the front seal. I changed to 100W and the problem went away. I haven't used it in anything except cars since.

On the float plane with all of the supports, braces, and wires underneath, the wind could be causing the oil to go everywhere, maybe even in George's battery box!
Dan