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Oil Over Board Out The Breather

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Dave Baxter

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I have about 16 hrs on my SA-100 single place Starduster as of yesterday, everything is pretty good so far. The PS-5C was a bit of a challenge, getting it dialed in as it only takes a few clicks one way or the other before the idle is to high to low or rich lean with idle mixture to far one way or the other! Runs really good and really smooth at 2500 rpm, will go clear to 2700 level flight 3000' full throttle also smooth if you let it. The biggest challenge is landing it, you have to be on your game every time, about one out of five landings are squeakers, and the rest are either bounces followed by chasing it back and forth across the white line. Its not an old mans airplane, and I guess I am an old man now? But it really keeps you on your toes. I have been using some of Rick Rice's advice/ suggestions as for a longer farther out turn from base to final, and this has helped.


I have a question for all you engine Guru's? Details:.... Have not done a compression test yet, but suspect it will be low? The oil temp is good about 85*C pretty consistent, oil pressure about 80 psi, but it is puking oil out the engine crank case vent, the rear cylinders are dry, the front are pumping a little oil, but are not fouling the plugs at all. I have cleaned and checked them several times over 16 hrs of flight time. The cylinders are GPU .010 oversize, and had about 100 hrs of previous flight time, honed the cylinders really good and also lapped the valve seats, have done similar things with other cylinders in the past and have been successful, maybe just lucky?. I am thinking they have not seated and are glazed and have a certain amount of blow by, and this leads to excessive crank case pressure. But if this is the case a lot of oil should be going past the rings fowling the plugs and out the exhaust, but the exhaust is clean? I plugged the original front vent port normally used on the O-290, and used a later O-320 accessory housing with oil cooler outlets and the rear vent there as on the later engines But may need to use the front vent, instead of the rear, or both? I think it is 3/4" diameter tubing size. I also have a homemade oil separator, and it may very well be the restriction? But have a similar one on both of our other airplanes that seem to work well and have done so for many yrs. Am thinking of bypassing the separator as I think it may be so small and see if this makes a difference? My question is do any you know what the average crank case pressure should be for these smaller engines, and if it is high what causes it (Blow By)? And what can be done to make it better? You guys help and indulgence would be most appreciated. Dave

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