lml@lancaironline.net Mailing List Archive

<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> From: n295v v Thanks Mike, for your observations gained while working at Cont and Piper. You have pointed out the leaning problem and the rust problem. In regards to the rust problem, I have noted that this engine has a tendency to produce enormous amounts of water vapor in the crankcase, and it seems to stay there, as evidenced by droplets forming in the underside of the Oil Dipstick Cap when the engine cools. Water is a normal byproduct of combustion. When I shut down my engine, I pop the dipstick cap so that the steam and water vapor can distill off naturally from the hot oil. It has occurred to me that this engine design (or perhaps the oil scavange can) may be too vapor-tight, keeping water inside instead of letting it naturally distill off during flight. This could also be a function of the synthetic oil lubricants--perhaps they have an increased affinity for water--hygroscopicity in chemical terms. If the water vapor can't escape the engine, it will naturally seek cooler surfaces in the engine to condense upon--what better surface than cylinder walls--which because of their location and fins, cool first. This, combined with the well-documented information that the synthetic oils flow over a period of time and thin down to the point where they are practically useless for surface protection, may allow us to conclude that we should be looking at engine vapor as a major culprit. A dry nitrogen bleed into the oil in the crankcase for a half hour after shut down would solve this problem. Don't laugh! You can buy a lot of nitrogen for the price of six cylinders or a new camshaft. Or, maintaining some amount of heat to the crankcase by use of the Tanis Heater may aid in ridding the engine of moisture. Care would have to be taken not to char the oil, or degrade it over a period of time. David Jones LML website: http://www.olsusa.com/Users/Mkaye/maillist.html Builders' Bookstore: http://www.buildersbooks.com/lancair Please send your photos and drawings to marvkaye@olsusa.com.