Nissan D21Pickup P-Reg - Smoke from the Rocker breather - tymbian

The breather pipe from the rocker cover goes down around the back of the engine and into the chassis. This has recently started to smoke and seems like white/grey smoke is being forced along the box-framed chassis. When I take the oil filler cap off the same colour smoke is swirling around inside the rocker.

Nissan D21Pickup P-Reg - Smoke from the Rocker breather - Peter.N.

What does it smell of? If its a burnt oily smell it could be combustion gasses due to engine wear, if its a sweet oily smell could be due to fuel somehow getting into the sump.