[Vwdiesel] PCV vents

Shawn Wright swright at zuiko.sls.bc.ca
Wed May 24 17:40:50 EDT 2006

On 24 May 2006 at 11:38, Libbybapa at wmconnect.com <Libbybapa at wmconnect.com> wrote:

> In a message dated 5/23/06 11:36:36 PM US Mountain Standard Time, 
> LBaird119 at aol.com writes:
> > IIRC that has nothing to do with oil separation.  It's an anti overpressure
> > device similar to what Ford pickups have (at least the older diesel ones.) I
> > can't remember exactly how it works but something to do with more pressure in
> > the intake than the crankcase or vise versa.
> > 
> I don't quite get that for a couple of reasons.  The intake (pre-turbo where the
> vent enters) will always be less pressure than the crankcase any time the engine
> is running.  I can't see any reason to add a valve that let's crankcase pressure
> build higher than it would otherwise???  Why would VW add a complicated plastic
> part that didn't really accomplish anything.  From personal experience it does a
> very good job taking oil out of the crank vent.  Has anyone here ever had a
> runaway on their TD with the puck properly installed in the valve cover?  Anyone
> had a runaway without the puck?

Yes, on this very same engine, before the rebuild. With the puck, a plugged air filter, and a bit 
too much oil in the engine, it ran away quite nicely. Started out as a weird 'after pull' on 
acceleration when shifting, then finally after getting on the highway in 5th on a slight hill, it just 
keep on going. I had to pull over in 5th, thought it was done, pushed in clutch and it took off 
again, so I dumped the clutch to kill it. Not having any tools, I had it towed to town (free 
towing) and they dumped the oil and cleaned the intake, replaced air filter. Never happened 
again. I think the puck is a separator/condensor, but needs to be very close to level to work 
correctly, which is hard to achieve in a 50 deg layout without moving it elsewhere. I've looked 
closely and can see no sign of a valve in it.
It probably does work well on an engine with normal blowby...

Shawn Wright
'88 Westy 1.6TD 5 speed
'85 Jetta Diesel 1.6NA

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