If you think CCV problems then first remove all hoses (one at a time so you know where it goes) and check for splits and blockages etc. Replace any thing suspect. Clean out and test any valves. Once you are happy with those results run up to temp and briefly remove the oil filler cap. Check for excessive blow past. Post results and we will see if we can help more.
Good - Fast - Cheap: Pick any two.
E23 735i; E32 735iL (X 2 - 1 Alpine White and 1 Glacier Blue); E34 535i; E38 735iL; R50 Cooper; R55 Cooper Clubman.
E21 318i; E30 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i