ccsmith51

ccsmith51

Well Known Member
Well, not my belly, as large as it may be, but the belly of my RV-4.

It seems that after every flight I have some oil on the belly from the breather hose. It comes straight from the top of the crankcase and I have it cut flush with the bottom of the fuselage, next to the firewall.

I thought that it might be from me regularly doing rolls when I fly. So today I made a 0.47 flight in the calmest air I think I have ever flown in. And I made no abrupt maneuvers, no rolls, nothing but the kind of flying I would do if I was taking an 85 year old grandmother up for her first flight in a light plane.

But when I got back down to the hangar I checked, and there was oil on the belly, from the breather.

Is this normal? If so, why? Can I stop it? O-360 and I usually run 6 - 6.5 qts.

Thanks,
 
Thanks, Reiley. I have their oil filter and axel nut wrenches and they are great products. I'll get in touch with Allan to discuss a separator for my plane. :)
 
A suggestion:the flat breather tube is creating a venturi and drawing a vacuum on your crankcase. Bevil the tube such that it is slightly angled toward the front of the plane.
 
AltonD said:
A suggestion:the flat breather tube is creating a venturi and drawing a vacuum on your crankcase. Bevil the tube such that it is slightly angled toward the front of the plane.
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This will help for sure... there will still be some oil on the belly. :)
 
Yep. No ill effect. It is more of no vacuum sucking the oil mist out of the crankcase.
 
In the Van's Kit the tube is bent slightly forward and directed to the pilot side exhaust pipe with a couple of whistle slots cut into the tube.
 
I run no more than 6 quarts. If I do, all it does is spit it out...I have a bevel and a couple of holes in the tube further up on the vertical part.

From what I understand, this is pretty normal for an O-360 with nothing but a vent tube.

Some people claim that if you pressurize it a little, it will promote oil leaks from the case and accessories. Not sure if this is true or not.
 
Mine spit oil a few drops at a time (rolls or not) until I let it settle where it wanted to be. At 5.5 Qt, i'm not losing it on the belly nor is the level dropping. No separator, just a line from the breather to the bottom of the firewall. Free end is cut at 45 degrees as suggested above.
 
Brantel said:
I run no more than 6 quarts. If I do, all it does is spit it out...I have a bevel and a couple of holes in the tube further up on the vertical part.
Click to expand...

Me, Dos. Took me a while to learn that though. I thought my consumption was 1qt/2hrs. quit filling it to 6.5 or 7qts made things much better
 
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