Q: I have an O.S 81 FS & 110 FS with the closed crankcase–no external vent or nipple. What advice can you give me for shutting down after each flying session? It is not practical to remove the glo plug each day to load after run oil. The aluminum head & steel threads on the glo plug — not a good combination to remove/replace 3 or 4 times a week.
I run the engine full throttle & pull off the fuel line, then with glo driver on, turn it over for several seconds with electric starter to burn out as much as possible. I use Wildcat 2 & 4 stroke fuel, 18% synthetic. With each new gallon, I ad 6.6 oz of Klotz Benol to bring total oil content to 22%. Despite this, I have had rear bearing failure on the 110. Thank you for your help. Keep up the good work–I have enjoyed your column since 1977.
A: Your engine shut down procedure is fine, but unfortunately, this only gets rid of the excess fuel in the combustion chamber while still leaving the acid by-products of combustion in the crankcase. I’m afraid O.S. didn’t take this into consideration when coming up with their closed system. Removing the muffler and injecting a heavy load of Marvel Mystery Oil or other good penetrating oil while turning the engine over will get some of the oil into the lower end. The best solution, however, is to drill and tap the crankcase for a vent fitting through which the oil can be injected. Then plug the vent with a short length of fuel line and a screw. I have already brought this problem to O.S.’s attention and suggested they add a vent fitting.