[pierre smith]

How can a front seal be pushed out of a 4 cylinder Lycoming if the breather tube is not plugged, nor fitted to the exhaust with that controversial orifice?

It happened a couple of days ago near here.....details later.

Best,

 

[Mel]

Running a F/P prop without the rear plug pearced/removed will cause this.

 

[Ralph Inkster]

or insufficient or wrong adhesive applied or applied to dirty surface
or retainer ring not installed (some applications)
or wrong seal (split / not split)
or incorrect 'clocking' split seal on installation
or stuck relief valve
or ...
Could the thermister or filter bypass cause a surge?
I also seem to remember oversized seals being available for overbore cases.