If I did it correctly, there should be a picture of the air/oil separator I removed from the wet vacuum pump in my PA-24/250. My parts manual shows it to be a Piper part 486-380. Its plumbed correctly and the oil return is going into the fitting on the back of my O-540 crank case. The problem (maybe) is that it still spits oil out of the vent hose leaving an area of splattered oil on my belly about the size of a basket ball for every hour or so of flying. I've removed, flushed and inspected it and replaced all the lines with no improvement. My question is, 1) is this probably normal and if not, any suggestions beyond what I've just done? The engine has about 1400 hours on it. 2) The oil return nipple on the bottom of the separator is something like .5 inch in diameter but the end has a restrictor plate and the exit is reduced to a hole about the size of pencil lead. Why is that? My instinct is to drill this hole larger since all other separators for vacuum pumps seem to have at least .25 inch hole.

If someone can educate me on this I'm all ears.

Thanks, Dan

My 250 does the same thing. I actually had the oil seperator exhaust hose replaced at the Savannah Convention and it slowed it down considerably. I keep the oil level at 9 quarts which seems high according to other bloggers (see Oil Consumption). That may have something to do with it? Dont know.

Daniel ,
I have a '61-250 and am an A&P but ran into this problem on a CAF C-47 . we tried everything but the #1 engine would puke out a big gob of oil at engine start and had a higher burn rate than the #2 eng. I finally cut the air/oil seperator in half and found the outflow pipe was partially blocked . I see you noticed the outside pipe that the return hose attaches to is bigger than the internal outflow pipe . I "cleaned out " our seperator by using a drill up the outside pipe that was a little smaller than the outside pipe to drill out the smaller inside pipe and flushed out all the debris .
Problem solved , no more puking oil

Marty

daniel,

i jumped right to the air wolf and got a dry belly. you know, a little oil goes a long way. i didn't really notice any change in oil consumption on my 180. it is still around 10 hours per quart.

love that dry belly, though.

bob williams

The Air Wolfe, formerly Walker oil separator is probably the best unit sold. That tiny unit originally installed only works well when there is little discharge to begin with. The root problem is excessive blow by and the cure for that is a new top end.

Another less elegant solution is to tie wrap a plastic water bottle to the end of the breather line. Make the breather line shorter so it lies about 4" above the bottom of the bottle. The oily vapor will coalesce inside the bottle. The remainder exits the top of the bottle. The amount of oil discharged in the bottle between oil changes should be less than a couple of ounces. Cut the tie wrap and drain when you change the oil. I had an O-300 that was an oil belching monster. It completely stopped the oily belly problem without pumping that nasty sludge back into the crankcase.