Check your crank pulley does not have a hairline crack on the key way and also that it is not worn and also is perfectly smooth and round on any surface that comes into contact with the seal, and use a Nissan seal with grease on it on installation.
Right- conical washers, do they point in or out? I just can't get the crank pully to stop leaking I've inspected for cracks, given the inside/outside a good surface finish and changed the seal and washer.
It should be centre tallest part pointing towards bolt head, clean it all off with brake cleaner, put a smidgen of blue thread lock on the threads and sealant between the washer and pulley, then torque it up to spec.
Given it another 2 trys yesterday. Have used different bolts and new seal. I tried pushing the seal in so its flush with the pump and I've tried pushing the seal in using the pulley both with no positive effect. Today I'm trying with a different pulley then I'm all out of ideas