[Vwdiesel] PCV operation;blowby and runaway

[Shawn Wright]

On 25 May 2006 at 22:28, The President <quantum-man at hotmail.co.uk> wrote:

> Brian
> thanks for translating (Some folks don't like talking to foreigners ;o)
> 
> Surely operation of this valve is easily determined...
> It either operates from vacuum or (blocked airfilter/over revving) or 
> excessive blowby pressure. Check with an airhose or a vaccum cleaner... Or
> neither Doesn't blowby decrease with rpm anyway. It definitely does in the lower
> speedswhen rising from idle... If the PCV does restrict air flow; then doesn't
> this cause blowby (oil spillage in the turbo)? Even runaway in a slack turbo?

The TD PCV 'valve' appears to be just another way to attempt to scavenge the oil mist - the 
flow goes up into the 3" round disc, then must flow out through the horizontal exit through a 
small 1/2" or so hole. Any oil which splatters inside the disc is encouraged to run back into 
the engine. I can see no sign of a valve in mine. I suppose a restricted PCV could make a 
poor turbo drain back up enough to blow oil past the seals. Certainly a plugged turbo drain 
will do that, as I found out... it didn't run away though, but might have if I didn't catch it I 
guess.


Shawn Wright
http://members.shaw.ca/vwdiesels
'88 Westy 1.6TD 5 speed
'85 Jetta Diesel 1.6NA