[urq] Oil Catch Can Installation

[Ben Swann]

I ended up installing a temporary solution in place of my existing and incorrect PVC
routing - at least I think it was incorrect.  There was a set of valves - one a small
orifice plug where original PVC valve takes off from the Y going to valve cover and
crankcase.  In line with the orfice was also another PVC Valve.  This valve closed on
moderate pressure in either direction.  Why I did this made sense at first, but had some
problems.  I belive there was pressure buildup on boost and on decel valve closed in
opposite direction.  The interesting side effect was occasionally there would be oil
smoke when transitioning from boost to decel.  Also, the closed system made interesting
noises when under engine vacuum.  So on to attempt to imprve on system.  
 
I had obtained a nice canister catch can, but it essentially was too large for good fit.
So in mean time I decided to try a water separator that is typically used on a
compresser with paint setup or air tools.  This is a clear container with a baffle,
drain at bottom and inlet and outlet where I installed appropriate barb fittings.
 
I installed a stock PVC valve back in original location - this valve opens away from the
valve cover.    The line from PVC valve goes directly into catch can.  I took venturi
vacuum port off J-hose going into turbo - this fitting as I understand should provide
increased vaccum with greater airflow.  At first seemed to work OK, until engine warmed
up.  No nasty smoke puffs when shifting.   As engine got hot, I noticed smoke from
exhaust but only at idle or moderate decel - or if I gun the engine.  No smoke seen
under boost.  It is definately oil smoke.  disconnecting the vacuum line from Tubo J
hose did not stop the smoke, but only tested for about one minute.
 
So - am I just buring off residual oil?  Is this catch can passing through too much oil
?  There is not a lot of baffling and no separate chamber as I've seen on some or steel
wool for oil to condense on.  Or do I have another problem - like bad valve seal?
Interesting this happened just after making the installation - now smoke at idle but not
on shifting where engine goes from boost to vacuum.
 
I'll likely get a proper catch can, but making sure I even have it installed correctly.
Maybe the line at turbo creates too much vacuum, expecially when under boost.
 
Ideas?
 
Ben

  _____  

From: Ben Swann [mailto:benswann at verizon.net] 
Sent: Thursday, September 03, 2009 7:27 AM
To: quattro at audifans.com; urq at audifans.com
Cc: 'Ben Swann'
Subject: Oil Catch Can Installation




I am in process of installing a catch can.  Engine is MC1, NF head, and no CIS.
Megaquirt EFI and so intake is open to turbo inlet with only a filter and bypass
valve(actually just a blowoff).

Presently there is a PVC valve off the cam cover in stock location.  I am wondering if
to retain a PVC valve or just eliminate it.  The current system whistles, particularly
at idle and seems to not do a good job of alleviating pressure from the valve cover.
Also seems to be variations on PVC valve - some are bi-directional with spring operation
in both directions, so which version to use?

Also where is best to put return line?  Is the fitting located on turbo housing good for
drawing fumes off the can?  This was going to the frequency valve, but I have eliminated
using this. 

Ben