Cessna 120-140 Association

My breather is putting oil on my belly I read some time back there was a mod that could be done to the elbow to stop most of oil coming out does any one know the mod and what is the procedure to achieve good results
Rod

The breather tube is expelling vapor that includes oil. There is really not anyway to stop it. If the compressions are low due to worn rings it will be more, but there is always some.

The AN842-10 fitting that is mounted on the forward top edge of the engine case is catching oil that is being thrown from the crankshaft as it turns. The easiest fix is shown in the attachment under the crankcase breather improvement paragraph. You could either buy the part from Continental, or remove it and have some one install the extension pipe.

http://150cessna.tripod.com/c150o200ainsp.html

It depends on the why. If the engine has a lot of blow-by there's not much you can do about it. Excess crankcase pressure for whatever reason (leaky crank shaft seal, for example) has the same effect. It is sometimes helpful to route the breather line up and over the cylinders, then down and out. This gives the oil some time to condense and flow back into the engine. The elbow mod is to prevent the crankshaft from slinging oil directly into the breather fitting, but was originally developed for engines used in acrobatics. Also, if the outlet of the breather is positioned such that airflow creates a suction on it, that will also contribute to excess oil on the belly.

The elbow extension is to keep the oil from being expelled when doing aerobatics. The slinger ring is ahead of the elbow and the oil is channeled back into the case. I have tried the extended elbows and went back to the originals because they did no good.

I have the Elbow extension and I routed the oil breather line over the top of the cylinders. It made a noticeable improvement.

Note of caution:
IF you route the oil breather tube over the top of the cylinders
And
You live in a cold environment/and or fly with temps close to freezing, (or below)

You will want to insulate the breather tube from the crankcase elbow at least as far back as the back baffle(up to where the breather line exits the baffle, back by the mags)

Reason being is that you can be expelling moisture from the engine and you don't want it to freeze up and block the tube as the water (and oil) is climbing up hill........so to speak.

Same reason for having a small diameter hole in the breather line above the bottom of the breather tube, so that portion of the tube doesn't freeze shut.

Thanks guys rerouted line over engine and so far have seen a lot less oil/water coming out have a good day
Rod