It sounds like the pto seal. it can be replaced without taking the engine apart. take the pulleys off and drill a small hole in the seal and put a screw in the hole and screw it in and the screw will pull the seal out then get a piece of pipe the same diameter as the seal and long enough so you can tap it in without hitting the crankshaft and your done. be sure to put oil on the outside and the inside of the seal. this will help with installation.
jon
January 2009