Thank you for allowing me to assist you, my name is Joe and I will be happy to assist you with your concern today.
First and foremost is to make sure you did not block or or drastically restrict the breather vent/hose.
Different things can cause this issue, of them are:
Incorrect installation of the seal, inferior parts and or defective, block surface where the seal seats has a problem such as worn or grooves in the crank, excess internal pressure and or not able to vent, excessive crank play/walking such as from a bearing,
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