Fri Jan 31, 2025 12:15 pm
Be careful with a "catch can". Needs to be monitored, and drained regularly.
Another thing I often see is a breather tube extending well below the bottom of the cowling. Apparently, some folks believe that will get the oil off the belly....it doesn't. I prefer the end of the breather just even with the bottom of the cowling.
Also, make absolutely certain that your breather tube, especially on a newly installed engine, has a small hole high up in the breather tube. This is often referred to as a "whistle slot". I drill a small hole in the upper portion of the breather, where the cowling will always be warm, then stick a small screwdriver in that hole, and bend UP on it, so that the metal is pushed inward. This prevents oil from being "scooped" out of the breather, but if the distal end of the breather freezes, it will prevent the engine case from pressurizing, which, by the way, MAY have been the cause of your mechanic needing to replace the prop seal....that's exactly what happens when the breather freezes-it pushes out the prop seal.
Here's a small snip from an article on the topic:
""Moisture is expelled from the engine crankcase through the breather tube which often extends through the bottom of the engine cowling into the air stream. Under very cold conditions, this moisture may freeze and continue a buildup of ice until the tube is completely blocked. It is normal practice for the airframe manufacturer to provide some means of preventing freeze-up of the crankcase breather tube. The breather tube may be insulated, it may be designed so the end is located in a hot area, it may be equipped with an electric heater, or it may incorporate a hole, notch or slot which is often called a "whistle slot".
MTV