Export thread

I have a Briggs and stranton 29447-0445-01 motor. I removed the front sump cover to replace the sump gasket and this round spring fell out. I have no idea where it goes. I have looked at the manual and online and can't find it anywhere. I looks like it might go over the end of the crank shaft but i want to be sure. Any ideas?

that appears to be a spring that goes around the inside radius of an oil seal.... dimensions about?

This is on a smaller push mower seal

Thanks that's what it was!