The seating in the block that the 12H865 oil pressure release valve sits in, when fitting the end with the slight taper goes into the block first.

Tapped M8 to make removal from the block easy. We recommend that you leave the old seating in the block if having it acid dipped or any other chemical cleaning as this can cause a slight amount of seating metal to be erased, therefore remove seat after cleanig before fitting the new one.