Hello I will help you with your question,
Is the seal just leaking or does it get pushed out?
Is this a manual transmission?
manual trany just leaks
Try measuring the play of the front pulley as someone presses the clutch to see if it moves more than a couple of thousandths of an inch. Each time the clutch is pressed about 800 lbs of forward thrust is placed on the back of the crankshaft and this will wear the thrust surface over time. If you hold the clutch in at lights that pressure is always applied and it wears faster.
If the crank is moving forward and back the seal will leak
The other possibility is that there is excess pressure in the crankcase. If the PCV is plugged or the intake in the valve cover is restricted the blowby from worn cylinders can cause enough pressure that it blows oil out the seal.
Let me know what you find and how I can help you
If you have a good surface and the thrust is good and there is not excessive blowby in the crankcase I am out of ideas so I will OPT OUT and open your question to all the experts. Maybe someone else has more suggestions for you
Sorry it was not what I sugested.
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