Crank seal will sometimes whine as it starts to go bad. Noise will change with RPM. More like a faint squeal.
Bob Japundza CFI A&PIA
N55BC RV-6 borrowed, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.