SaabCentral Forums banner

PCV v7, an attempt to understand the Saab PCV system and fix it properly

746 Views 23 Replies 7 Participants Last post by  teo.petleshkov
This a continuing of my thread bombing of Assessing correct Crankcase Ventilation function using OEM saab PCV valve specifications, and avoiding problems caused by defective or non-oem valves

I went down the rabbit hole and did a bunch of PCV and evap research (my 02 has an 06 biopower ecu, so it should have the new evap routing...anyways).

I was sketching up the "proper" way to do this PCV system and was quite pleased with myself. Then I went back to PCV6 to analyze the flow paths (since its not on this site) and realized that saab did nearly the same thing. See pictures below for PCV6. The issue with every dang version of the PCV system on the PCV cars has been oil usage... because saab sucks directly from the valve cover to the intake. If you wonder why people in the PCV6 threads from 2006 say oil consumption is still occurring; this is why. They finally fixed this on the 04 cars, but couldn't be bothered to implement the same idea on the PCV6 kit for everyone else.

Bumper Microphone Bicycle part Automotive exterior Audio equipment


Handwriting Rectangle Slope Font Parallel



So /rant. Onto the fix. Its quite simple looking at the above left picture; plug the small port at the valve cover and splice the hose leading to the check and intake in on the green line. Now the intake will suck in filtered air. In schematic format:
Handwriting Rectangle Slope Font Parallel



The only catch for this is that rerouting the check valve to the green line will end up sucking clean air straight from the oil filler into the catch can via the oil drain which is no better. No fresh air for the crank case. (it would actually potentially destroy the engine if the catch can inlet was ever blocked, see third post). I believe the 04+ catch cans route fresh air through the catch can, to the valve cover, down to the hole in the block, out into the second catch can cavity and finally into the intake manifold. A few solutions to "single catch can" below.
  1. Check valve the oil return to the pan (seems risky, it would probably never open due to pressure deltas)
  2. Plug the oil pan, valve the drain on the catch can and drain manually at an interval (ehhh...)
  3. Use a second catch can for the vacuum side of the PCV system which still requires manual draining (Ehh...) (unless its design properly and also drains to the pan?)

So what does #3 look like:
Rectangle Orange Slope Handwriting Font



But wait, there's more! with two catch cans, everything gets much simpler (valve wise). not sure which route is better exactly.

Handwriting Rectangle Slope Orange Font



Handwriting Rectangle Slope Font Parallel





So there are a few things to address here before making a final decision:
  1. Understand what the pcv6 and 04+ catch cans look like.
  2. Retrofit the 04+ catch can (im assuming it is designed correctly internally to filter intake vacuum air) or fab a new catch can.
  3. The "single catch can" design can be used with the additional requirement that the drain be plugged and it be drained manually (every oil change?)
  4. The PCV system can be converted to something like "dual catch can v2" and the second can will have to be drained occasionally.

    And a couples notes:

  • "Catch can v2" will be most effective as a PCV system.
  • I need to look at how more modern turbo motors do PCV. I would guess it is down to correct catch can design?
  • some kind of restriction or flow metering is required for the intake vacuum path. Most pcv valves seem to be a 2in1 that use a spring and ball to regulate and check for boost. See typical internal diagram:
Rectangle Line Font Parallel Drawing
21 - 24 of 24 Posts

· Registered
Joined
·
2 Posts
Hi guys! I am having troubles with high oil consumption on my 2002 2.3 even after updating to PCV 6. After a lot of reading and thinking on how pcv 6 works, i believe that the position of the nipple on the cover does matter. If you rotate the nipple to a position where the thin line with the check valve, going after the throttle body, is going up verticaly, then maybe it will suck just vapours and no liquid oil. What do you think about that?
 

· Registered
SAAB 95 - 2004 Linear Ltd Wagon
Joined
·
270 Posts
Hi guys! I am having troubles with high oil consumption on my 2002 2.3 even after updating to PCV 6.
you will find it easier to get help if you start a new post with you problem description, here it will be out of sight for other forum users who might be able to help you (and will sidetrack the current topic).
with any high oil consumption that might be linked to the PCV system, do a glove test first to get an indication of pressure (bad) or slight vacuum (good) in the PCV system. after replacing the pcv kit #6 you might also need to take the valve cover off (get a new seal first) to clean the internal lubrication pipes that are part of the PCV system (read Saab Bulletin Nbr: TA210-0509 for 1998-2003 models)
 

· Registered
Joined
·
2 Posts
Thank you for your answer, Silver2u! I guess I didn't express myself correctly. I'm not looking to get help with my high oil consumption. There are enough topics on that matter, I don't want to start another one :) Just wanted to direct your attention to the nipple in question, because noone seems to consider it's position, and how it affects the system efficiency. I believe it does affect it, so what do you guys think?
 
21 - 24 of 24 Posts
Top