Les Holman Oil breather separator

[s johnson]

Sorry I posted one of the pictures twice. Here is the other picture.

Scott

[Bob Wood]

Here is my Red Bull separator. Drilled aluminum tube thru a grommet to keep it tight.  Holes drilled in the bottom of the tube and thru the can midway up the side.
Not a drop anywhere anymore.

Bob

[BobSeverance]

flyover1974: I also have a reed valve on my engine to keep negative pressure in my engine therefore eliminating any of the exhaust gasses from entering my engine. Much like every other 2 cyl boxer modified VW engine. Some pressure is always in that tube never any exhaust.

[Mark Kramer]

Well, even though this discussion is a little old, it is a current problem for me. I have a 1992 Mosler cb40. Mosler case, not vw. Have original paperwork from when it was test run at factory. It has a 1 inch hole in the top where a breather should be, I think. No threaded holes for bolts. Also was not drilled for a dip stick. I think it was supposed to have some kind of breather/filler combo I’ve read about, but I have never seen one if it exists. No matter what I have tried, I get a lot of oil along with the crankcase pressure out of the hole. The engine case is only supposed to have 1.25 quarts oil inside, with this small amount,I feel a loss of any is unacceptable. My last attempt was a check valve in the hole at the top, with a hose to a vented separator, draining out the bottom thru a hose to the rear bottom of the crankcase. Within one minute of running, there was oil pushing out of the air filter on top of the catch/separator can. There’s got to be an easier way to vent the crank case without losing oil.
Any ideas?
Thanks Mark

[leshoman]

​on the 1/2VW engine i had there was a reed valve that would let air out of crankcase but no air back in.  Air leaving went to catch can and in a years flying i might have a couple thimble fulls of oils 

[Mark Kramer]

Hi Les, I don’t have any bolt holes to install a reed valve assembly. I have a check valve there which only allows pressure out, nothing back in. From there to a catch can which is vented to the outside. From the bottom of the can a hose back to the crankcase at the very bottom. ( an attempt to put the captured oil back in). Oil gushes out of the vent on top of the can. Does the reed valve do something that the check valve doesn’t?
Love your videos Les... keep em coming.
Mark

[leshoman]

You may have something else going on with your engine

[Tom XL-7]

The hose returning oil to the crankcase would need a check valve stopping oil from traveling out of the crankcase. On a 1/2 vw the entire crankcase changes pressure with piston movement sucking or blowing. If that line is below oil level your pumping oil out. Most of the stuff I have seen in a catch can I wouldn't want to return.  Remove the return to see if it solves your problem.

[Mark Kramer]

Hey Tom,
I am going to do away with the oil return to crankcase. The last time I ran it with a check valve in the top of the engine, to a hose into a soda bottle, it spewed out a good inch into the bottle. The capacity is 1.25 qts in the crank case. I feel like I can’t afford that much oil coming out, hence my efforts to let it flow back in. I do not have what ever it had for a pcv valve. Also there are no bolt holes on top next to the blow by hole. So I cannot simply bolt on a vw style breather. I am certain I will come up with something. My biggest question right now is whether or not I need a check valve at the breather hole. Doesn’t blow by mean that the crank case can have only positive pressure? If so ,why the check valve? Maybe there are low pressure pulses in between highs. I’m planning on a simple can with the scrubbie stuff inside right on top of the  hole on top of the engine, with a breather filter on the top.
Any thoughts?
Mark

[Tom XL-7]

On a two-cylinder horizontally opposed engine we have two pistons either traveling outward or inwards together. This changes the crankcase volume decreasing on the inward and increasing on the outward travel. The change is equal to the bore and stoke times two. On the 4cylinder two of them travel in the opposite direction so volume stays constant. But we have removed the volume balancing pair. Thus the blow and the suck. The reed or check valves are installed to let the air out but not so readily back in thus running some negative pressure on one of the strokes and the high-pressure stroke just put things back at normal. It is not good to let air back in as it carries moisture and perhaps dirt. So an open breather would simply throw oil mist air at you and then pull outside air back in.  An oily mess as well as constant loss

[Mark Kramer]

Ok, I hear ya. So with a check valve or reed valve there will be negative pressure and positive pressure pulses? And the one way valve stops pressure build up, and stops contaminates from entering. My issue with this engine is that an excessive amount of oil comes out of this hole with the pressure. Engine sump only holds 1.25 guarts. Can’t afford to lose any. Some how got to stop oil from coming out while allowing the pressure out.

[Dan_]

Your mission --should you decide to accept it is to cover said hole with the hummel reed valve setup, plug the hole and make a new one that fits the hummel reed valve setup or plumb a line from said hole to a remote location with the hummel reed valve set up.

Harley and Beemer bikes use similar means, but are required by emission standards to return the crankcase fumes to the air filter to be burnt.  Google Harley crankcase ventilation.

[Bob Wood]

Just an update on my Red Bull oil separator,  see see my 2017 post below. I finally took it off to clean it and check for oil. So in 3 years I flew 140 hours with the gizmo on and found about 1/4 teaspoon of oil in the bottom of the can.  I have no oil anyplace on the plane except the occasional drop or 2 after replacing rocker covers.  Works very well.

Bob Wood

[Mark Kramer]

Dan, I think the reed valve set up is probably the way to go. Will probably have to mount remotely, as the flat spot on top of the engine is I think not large enough. Bob, what is on the top of your engine that the hose to your Red Bull can originates from? I would like to have a reed valve small enough to fit the top of my Mosler case. I’ve seen a picture of one in the Mosler manual, but not able to find one. The Hummel list shows two, a small one and a large one. Wonder what the small one looks like?

[Bob Wood]

Mark,
All I have on top is the reed valve breather from Scott Casler. Just a clear hose off of that to the can.

Bob