Has anyone ever experienced a broken flexplate? My friend has a 80 300D NA that is making a hellacious knocking sound. The motor keeps running faithfully which leads me to believe that the sound could be from a broken flexplate. What do ya'll think?

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Regards,
Ian White

1995 E300 Diesel w124 OM606
2014 E550 w212 M278 biturbo

2001 BMW 740i E38 M62 (past)
1981 300SD w126 OM617 (past)