All Things Mk5 > How to Guides / Troubleshooting

PCV and the inner workings of the system on the tfsi engine

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cuprak1:
The PCV system on the 2.0T is a complex one but nothing that's to difficult to figure out once you cut it apart on the bandsaw

The first thing to do is identify what all of these ports are doing.



PCV Gasses enter the valve cover through the port labeled Crank Inlet .

Once inside the valve cover there are a series of chambers, baffles, and drains. As gasses move through these ports they will eventually come to the Vacuum Control Diaphragm and Diagnostic Port.

The vacuum control diaphragm is used while the car is in vacuum. When vacuum is applied to the diaphragm it is sucked down to limit the amount of draw applied to everything behind it. In factory orientation if this diaphragm were to become ripped it would allow so much vacuum to be applied to the pcv system that oil would literally be sucked out of the head and into the motor.

Heading towards the intake manifold there is a Check Valve This is the valve that is known for failing on these cars. When working properly this valve opens under vacuum and closes under boost.

When in vacuum pcv gasses are pulled through the diagnostic port and into the intake manifold. When in boost the pcv gasses go out the other side of the diagnostic port and into a passage molded into the valve cover then out the Rear Outlet

You can follow along with the flow of gasses through this image.



So what this all boils down to is that there is no "Front" or "Rear" PCV. Its all one system. What people refer to as a rear pcv is just a passage built into the valve cover. A few of the different revisions had different check valve orientation but the function and layout is the same across all the cars.

I hope that taught you something about your toy!

Phil@BSH:
You're welcome.  :wink:

Top Cat:

--- Quote from: Phil@BSH on October 28, 2009, 08:36:32 pm ---You're welcome.  :wink:

--- End quote ---

 Who is.  :chicken:

I think you got that wrong your suppose to say hi my name is Phil and we say your welcome here.  :signLOL:   :happy2:

KRL:

--- Quote from: Phil@BSH on October 28, 2009, 08:36:32 pm ---You're welcome.  :wink:

--- End quote ---

Hi Phil!

Great to see you on here and welcome aboard  :drinking:

Phil@BSH:

--- Quote from: Top Cat on October 28, 2009, 08:43:35 pm ---
--- Quote from: Phil@BSH on October 28, 2009, 08:36:32 pm ---You're welcome.  :wink:

--- End quote ---

 Who is.  :chicken:

I think you got that wrong your suppose to say hi my name is Phil and we say your welcome here.  :signLOL:   :happy2:

--- End quote ---

The OP is. I wrote that and made all the diagrams  :wink: I dont mind though!

However, hi my name is Phill, thanks for having me on the site!

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