Go Back  AudiWorld Forums > Technical Discussion > Engines > 2.7T V6 Discussion
Reload this Page >

custom PCV and catch can install

custom PCV and catch can install

Old 03-13-2018, 06:13 PM
Audiworld Junior Member
Thread Starter
Join Date: Apr 2011
Posts: 13
Default custom PCV and catch can install

I have successfully installed a custom PCV and catch can system, in my allroad, that is working great. Here is some of the what, how, and why:
First I removed all the SAIP stuff (secondary air injection pump). That crap just gets in the way. I got block off plates from ECS. I think there are posts somewhere on how to do this. Doing that didn't even throw a code on my car.
Here is what the stock PCV system looks like:

here is my schematic interpretation of the components:

After a lot of studying and some trial and error this is what I am using:

the directional arrows indicate vapor flow during throttle on conditions. Notice that it is two separate systems. One is the out gassing of the crankcase through the catch can and PCV into the intake manifold. The other is the in gassing from atmosphere air (nipple on the side of the "Y" pipe) into the valve covers. I think this set up is working really well. The piston blow by gasses get sucked out through the crankcase breather, to the catch can, then through the PCV valve, and into the intake manifold. Then, fresh air comes in from the valve covers, which get the air from the filtered atmosphere air from the "Y" pipe. I got the idea for this schematic from a GM aftermarket LS6 schematic. Two previous schematics that I used ended up not venting properly and led to horrific smoke from the tailpipes. This was from increased oil pressure in the turbos caused by positive crankcase pressure.

I should have taken some pics with the "Y" pipe off, but I didn't think of posting till later.
I used 1/2" and 3/8" oil hose, and black nylon plastic plumbing fittings (got them from USplastics)
I used a small two port Mishimoto oil catch can.
I'll explain the valve cover/ atmosphere run first:
Here's a pic at the passenger side valve cover:

In this picture I disconnected the electrical connector for the N75 valve so you can see the stock connector and pipe from the valve cover inlet to the fitting for the N75 valve tee. At that tee I connected 1/2" oil hose (it took a good deal of heat and twisting and pushing). From there the 1/2" hose bends toward the driver's side where it joins a 1/2" black nylon tee:

The hose on the passenger side of the tee came from the passenger side valve cover.
The hose on the top of the tee goes to the PRV and the "Y" pipe (atmosphere is what I call it, between MAF and TB):

The hose on the driver's side of the tee goes to the driver's side valve cover:

Again; heat gun and lots of twisting to get the 1/2" oil hose onto stock fitting.

Now for the crankcase breather, PCV, and catch can plumbing:
I have to explain some of it because I didn't take pics, sorry.
The crankcase breather is located under the intake manifold (see picture of stock PCV system, the lowest hose, in middle, went to this). It is like a snorkel that sits on top of the valley area between the heads. Just like the valve cover vents I used 1/2" ID oil hose that I attached to the stock connector fitting. From the fitting I used a 5" section of hose, then a 90 degree barb fitting and a section of hose to the catch can.
I used 3/8" ID oil hose for the catch can to intake manifold run. I figured their shouldn't be oil in it, so it shouldn't clog with oil sludge, so I could use thinner diameter, and also; the intake manifold connector fitting and PCV valve is a smaller diameter, and fit the 3/8" hose.
See the previous picture of the stock PCV system... Notice the central canister that all the tubes go to.... Notice the top middle tube and fitting. I used this fitting (just cut the plastic tubing off it with a knife). I also cut the PCV valve out of the tube near this fitting. Notice how this fitting angles toward the passenger side. I used a 5" long piece of 3/8" diameter oil hose on this fitting. Then I connected a 3/8" 90 degree angle hose barb fitting and angled it towards the driver's side and the catch can location.

From the 3/8" 90 degree fitting I attached in this order: 2" piece of 3/8" hose, PCV valve, then 3/8" hose to catch can.
here's a picture of these two hoses:

They are the ones right under the coolant res.
Here's a pic of the catch can:

That's an aftermarket fan control module on top of it (another story, maybe I'll post that project later).
Underneath the catch can is a drain, which consists of: npt barb fitting, 1/4" ID oil hose that I routed behind driver's side intercooler, and a simple shut off valve (in picture of plumbing parts)

I couldn't find any good DIY PCV valve-catch can posts when I started this project. It took a lot of studying and a couple mistakes before I got it right.
Bergelvis is offline  
Related Topics
Thread Starter
Last Post
TT (Mk1) Discussion
10-25-2008 11:13 AM
A4 (B5 Platform) Discussion
08-14-2008 05:44 AM
S4 / RS4 (B5 Platform) Discussion
07-01-2006 05:52 PM
S4 / RS4 (B5 Platform) Discussion
11-09-2002 08:14 PM
S4 / RS4 (B5 Platform) Discussion
09-01-2002 03:44 PM

Thread Tools
Search this Thread
Quick Reply: custom PCV and catch can install

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: