Troybuilt oil leak

[pawandmaw]

I have 31p777 0293e1 0401312d 18.5 Briggs, is leaking oil on the drive pulley below the engine. I believe the crank seal went on it. Note this engine did have gas in the oil, the oil leak appeared after it ran 20 hours after the carb was replaced and oil replaced. How hard is it to put a new seal in once the engine is off? And WHY did the seal go ?? The oil is mostly on the pulley so I am 90 percent sure the crank seal is the culprit.
Thanks for your time and input
Paw

[bgsengine]

If it is the crank seal, don't even need to remove the engine - pop the PTO and crank pulley off, pop seal out, put new one in and done.. if you don't mind working on your back like an auto mechanic, it's quick and easy, provided the PTO clutch and drive pulley slide off easily.. Considering that it is an oil leak out the seal (if it IS) the chances are good that oil (and wax components in the oil) have heated enough and seeped down through so pulleys may just slide off without even any prying.

However, these (and some Kawasaki engines) also seem to have a nasty habit of getting the sump bolts just loose enough that the engine base gasket gets sucked into the crankcase and oil leaks out there and down.. (leak is often found right under the cylinder cooling fins, tough spot to really see it) I'd also be taking a close look at whether there might be a very slightly blown head gasket that may be over-pressurizing the crankcase - forcing oil out various places.. but not so badly blown that the breather is unable to drain the oil vapors back..