Date:         Tue, 1 Dec 2009 02:04:51 -0500
Reply-To:     Sam Payne <bungeegull@HOTMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Sam Payne <bungeegull@HOTMAIL.COM>
Subject:      info needed on crancase ventilation systems (mostly I4)

Hi,

      I've been away from the list and my van for awhile but am finally
getting back into both.
      I have an '86 westy which I put an inline 4 into (2 liter Audi 3A)
run by a Bosch Jetronic fuel injection system, based on excellent research
done by Frank Grunethaner (see my previous posts).
    The van drives and I'm quite happy with it, but the crankcase
ventilation system as I plumbed it collects too much oil (engine
compression is perfect), so I'd like to modify it. The problem is that I
think I see several different ventilation strategies out there, but am not
getting it entirely. If you know, please help!
     I've looked at crankcase vent strategies in VWs, Saabs, and BMWs in
the junkyard and think I see two basic methods:

    1.) fresh air is pulled in to vent the engine from a breather hose
running from a connector between the AFM and the throttle plate to the
valve cover, and blow-by is vented from the engine by a hose running
between the valve cover and the intake manifold. Saab does it like this.

    2.) On most VWs the vent seems to be just a hose running from the
valve cover to the air filter, with a large PCV valve at the valve cover.
No fresh air seems to be drawn in. S'up with THAT?

     I don't understand the operation/benefits of each method,
specifically:
    1.) In method #2, why is no fresh air drawn in? Is it enough to vent
blow-by only? Wouldn't that be less effective, especially for venting
moisture?
    2.) Why do some systems have no PCV valve? How do they regulate
vacuum, specifically the high vacuum at idle?
    3.) What method best fits a LH Jetronic FI system, which uses an air
mass meter.

     My engine has two vent points: the valve cover, and the side of the
block below the cylinder head water input. Most VW I4's have the block
vent blanked off. Can I do that?
    Or, should I input fresh air into one vent and output blowby fron the
other, more like the Saab method?
    Or, should I connect the vents and run them through a pcv valve and
down to the air filter?

           Many thanks for any help,       Sam Payne