<M42><E30> Where is Crank Case Vent Valve/Oil Separator?

[Dreamsound@xxxxxxx]

    My 1991 318is is consuming oil and I've been told I should suspect the 
Crank Case Ventilation Valve (aka Oil Separator).  There is a lot of oil 
inside the vacuum hoses and intake manifold; the theory is oil is getting 
into the intake system and burning up.
    I cannot find the faulty valve.  Two dealer parts guys looked for 30 
minutes and only found the valve for the E36 M42 motor (which has a 
completely different variable-length intake layout and different vacuum 
system) and the E30 M3, but not my E30 M42.
    I have been told (by my mechanic) that there *might* be a check valve in 
the E30 M42 Valve Cover, but it doesn't show up on the dealers computer and 
the Valve Cover costs $300...
    There has got to be something to keep the oil out of the vacuum system, 
where is it?  This should be an obscure BMW Trivia Question, I've got the 
dealer parts guys stumped...  :)
Thanks in advance,

Mike Crotty
1991 318is

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