Why is sealant not applied to the saddles on the forward, center and rear webs of the crankcase halves on Lycoming engines-? Sealant is only applied to the parting surfaces around the periphery of the crankcase halves on Lyc. engs. Continental engines apply sealant and silk thread to the forward, center and rear web parting surfaces. Since there is very slight movement between the case halves parting surfaces in the center of the engine, metal fretting sometimes occurs as well as oil ingression between the parting surfaces which eventually means metal wearing against itself and torque being lost on the thru bolt nuts. Then it is just a matter of time for having to do a premature engine disassembly. On another note, Lycoming engines have their camshaft mounted above the crankshaft which means no oil drip effect from the crankshaft on to the camshaft which results in premature rusting of the camshaft lobe(s) and lifter face(s) if the engine sits inactive for a period of time. Continental engines mount their engine camshafts below the crankshafts and are less prone to rusting of cam lobe(s) and lifter face(s). Having to remove the propeller and starter ring gear on a Lycoming engine to change an alternator belt is a bad design while this is not necessary on most Continental engines since they mount their starers and alternators on the accessory drive case meaning that no drive belt is required.
In my opinion, the areas around the main bearings are kept clean because of uncertainty about the thickness of any sealant or thread that would be applied, and how much it would crush. You'd have to ask the Lycoming design engineers to be sure... I just know that's how it's to be done. We don't see fretting as a problem very much, so I'm not sure your fears of premature disassembly are well founded. Through bolt torque is a concern, but I'd be more worried about extra material in the stack crushing further or eroding away than any risk of significant thickness being lost due to wear. More likely would be corrosion jacking. As for your observations about the cam location, I'd say every brand has its pros and cons. Cardinals are certified with Lycomings, so we run Lycomings. Based on what my Bonanza owning friends tell me, I'm very happy that we don't run Continentals. There are lots of Lycomings going well past TBO without needing new cylinders. But different strokes for different folks! I don't mine at all that you like what you have.
Keith, can you suggest a shop near us in Huntley that can do our 500 hr inspection on the Bendix Duel mag in our RV6A? The last time it was done in Rockford but they are temporary closed. We can ship it if needed. Thanks, John Dill
I think Poplar Grove Airmotive will rebuild it for you. They do rebuilds, and I think they'll do walk-ins. Good shop. As of 2023 at least... who knows when in the future someone might read this...
