Crank case pressurisation?

[Coops]

dont be fooled by thinking its the valley gasket,
i have had the same thing a few times, once it was the front pulley seal,
and also had the front of the sump leaking (where it meets the timing cover) these two problems also caused a pool of oil near the dizzy

[The Original Tom]

How can the pullye seal and the sump cause a pool at the top near the dizzy, it's a physical impossibility!
I'm not saying you're wrong just that I can't see how that works. There's also oil residue down the front of the block below the head gasket where it's leaked from what looks like the valley.
Unless the oil from the crank seal is flying directly up and landing next to the dizzy I can't see how it could, there's no oil on the dizzy cap or the inside of the bonnet like you'd expect. There's also no oil on the front of the timing cover directly below the seal which is where I'd expect it to leak from.
The samp may also be leaking but again how would that put a pool of oil at the top of the engine?