I have an oil leak on my briggs 12.5 it appears to be coming from the seal on the bottom. According to the person I just bought this from this seal was replaced are there any know issues with this engine regarding this. I guess it is possible they put the seal in and ruined it or something any help would be great. Not useable the way it is.

 

The seal was probably just installed incorrectly and is damaged, but...if the crankshaft or pulley is bent, or the crankshaft bushing in the engine is badly worn, or if the engine has overheated badly, it would damage the seal and cause your leak.

 

Another possibility is if the seal was removed improperly - with a pick-type probe - and the crank surface got scratched, deep enough to carve a channel, if you will, and allows oil to pass through this channel.