since 1940

Oil Leak at Crankshaft Nose seal on Lycoming or Continental Aircraft engine

1. Make sure engine crankcase is not being pressurized. Check engine breather to make sure it is not plugged. For
Continental engines refer to Service Bulletin M89-9 for procedures to use when inspecting for excessive
crankcase pressurization. Information in M89-9 is interesting and may be of some help with Lycoming engines
also.

2.For Continental engines install seal in accordance with Continental Service Bulletin M76-4. DO NOT
install nose seal until you have read this bulletin. It was published in 1976 and has served faithfully all these
years for those who have gleaned the knowledge contained in it.

2A. For Lycoming engines throw away the split seal and use the stretch style seal. Install in accordance
with Lycoming service instructions. Go to Lycoming Nose Seal Leakage

3. Repeat steps 1 & 2 until seal doesn't leak.

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Disclaimer: sacskyranch.com contains abundant information relating to aircraft maintenance. The information provided  is not intended to supercede or supplement the F.A.A. approved  maintenance and/or operator’s manuals. Those F.A.A. approved manuals must be utilized when performing maintenance and/or operating aircraft.