REFLECTOR:Air Oil Separator

Tue, 8 Apr 2003 08:37:15 EDT

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I made one for my IO540 very similar in design to Don White's. The return 
line is connected to an unused fitting in the block just behind cylinder #5. 
I checked with the engine rebuilder and he assured me that this is a "no 
pressure" fitting, thus allows the oil to drain back to the engine. As I 
recall it is a 1/2 inch pipe fitting.

The wrinkle is that this fitting has the same pressure on it as the breather 
when the engine is operating, thus when I first tested it I actually had a 
higher oil loss out the breather than before. I attacked this by installing 
an automotive PVC valve in this line. It is installed so that when the engine 
is running pressure closes this check valve and the oil actually collects in 
the bottom of the separator body. When the engine is shut down, any oil in 
the reservior drains back into the engine. 

An alternative would be to place a receptacle below the separator in which 
oil could collect. This would then require a periodic draining. The other 
downside is that a pint or so of oil in a fiberglass container in the engine 
compartment could contribute to a hellova engine fire should it somehow 
become ignited. With the drain line and automatic valve in the system, I 
suspect that no more than a couple of tablespoons of oil collects on any one 
flight.

Bob Wood
N658SE

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<HTML>I made one for my IO540 very similar in design to Don=20=
White's. The return line is connected to an unused fitting in the block just=
 behind cylinder #5. I checked with the engine rebuilder and he assured me t=
hat this is a "no pressure" fitting, thus allows the oil to drain back to th=
e engine. As I recall it is a 1/2 inch pipe fitting. 
 
The wrinkle is that this fitting has the same pressure on it as the breather=
 when the engine is operating, thus when I first tested it I actually had a=20=
higher oil loss out the breather than before. I attacked this by installing=20=
an automotive PVC valve in this line. It is installed so that when the engin=
e is running pressure closes this check valve and the oil actually collects=20=
in the bottom of the separator body. When the engine is shut down, any oil i=
n the reservior drains back into the engine. 
 
An alternative would be to place a receptacle below the separator in which o=
il could collect. This would then require a periodic draining. The other dow=
nside is that a pint or so of oil in a fiberglass container in the engine co=
mpartment could contribute to a hellova engine fire should it somehow become=
 ignited. With the drain line and automatic valve in the system, I suspect t=
hat no more than a couple of tablespoons of oil collects on any one flight.<=
BR>
 
Bob Wood 
N658SE</HTML>

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