Where are you seeing the oil leaking from? Can you post a photo? Are you sure it’s not from gas/oil residue in the exhaust housing running out? This is normal, especially after just running in a bucket. Are the surfaces where the seals touch the prop-shaft and driveshaft smooth? or do they have grooves worn in? You can usually see cracks in the housing halves. Have you very carefully replaced the rope seal between the housing halves by cutting to the proper length and putting a dab of sealer at each end?
When you changed the impeller, did you get the impeller key positioned where it should be? Are you running it with the water several inches above the cavitation plate? If you are just covering the water intake, it will not self prime, and your impeller will usually self-destruct in a minute or two.
Note that most of your 28 HP is based on he 1956 30 HP design and parts.
Dave
