working on the 84 volvo 240, and for some time now its been blowing oil out the filler cap and any other place it can find. this certainly appears to be a problem with the PCV system, but none of my local parts stores even list a PCV valve for it.
does it have some other system for this purpose? how do we go about fixing this

 

'flame trap'. its inside the oil seperator box under the intake manifold.

see Flame Trap FAQs

in reality, they are a royal pain to get to, and should be cleaned regularly (every oil change, even). you probably need a new one if its been plugged this long (and quite possibly a new oil separator box and some of the other plumbing in that area).

IPD sells a kit to raise it up above the intake manifold so it is easily serviced.
Product Search: FLAME TRAP RELOCATION KITS


p.s. turbos dont have them.

 

Turbos DO have them, they don't have the "flame trap" but they have the oil separator and that plugs up just as much, so a service of the separator is a good idea now and then although not as often as a real flame trap.