JD 300 with K341 leaking oil from front

[Greenday]

I have a JD 300 garden tractor with a kohler K341 16 horse engine that I recently overhauled. It runs great with lots of power but after running it for about 25 minutes it will start leaking oil out the front from behind the pto. I have replaced the seal twice, checked to make sure there is not a groove wore in the crank, checked the breather to make sure it is assembled correctly. Like I said it runs great with no smoke so I have no reason to think that I am getting blow-by causing to much crankcase pressure. The oil is coming from behind the pto clutch somewhere. Any Ideas? I have rebuilt and ran kohler engines in my pulling tractors for years but have never encountered a problem like this. I am pulling my hair out! Any ideas? Thanks Dave
 

[joe csuti]

Measure crank for wear where bearing rides,may be worn,if bearings not replaced check for wear,check bearing plate for wear,bearing may have spun in bearing plate,wearing recess for bearing,check crank end play,check bearing plate for hairline stress cracks.
 

[504]

Don t take this the wrong way, but is the seal in backwards? (I have done worse.) Check the breather valve too, they can stick and then they build crankcase pressure.
 

[Greenday]

Aha! I found the problem. Oil was seeping around where the camshaft pin press fits into the front of the block. I have no idea why it is leaking there and have never seen a kohler leak there before. I sealed the hole from the outside and no more oil leak!