PCV valve failure

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Info

The PCV valve (Positive Crankcase Ventilation valve) is a one-way air valve that allows the flow of "blow-by" gases and vapor to escape(as these gases and vapors are not good for mother earth) into the intake tract upstream of the MAF(because you don't want "dirty air" contaminating the MAF sensor) to be burned with the air/fuel mixture in the combustion chamber. The system consists of a rear valve that is attached to the turbo inlet to provide fresh air into the crankcase, and a front valve which allows air to flow only out of the crankcase and into the intake manifold. The air is not pressurized, it is pulled through the crankcase from rear to front by the vacuum maintained in the intake manifold.

During normal operation, a small amount of unburned fuel and exhaust gases can and do escape around the piston rings and enter the crankcase, referred to as "blow-by". If these gases remained in the crankcase and condensed, the oil would become more diluted over time, decreasing its ability to lubricate(sludge). Condensed water would also cause parts of the engine to rust. To counter this, a crankcase ventilation system exists to draw fresh air in from the air filter(or in our case the turbo inlet via the Rear PCV) and expel the gases out the PCV valve into the intake manifold.

If an engine is damaged or enters old age, gaps can form between the cylinder walls and pistons, resulting in larger amounts of blow-by than the crankcase ventilation system can handle. The gaps cause power loss, and ultimately mean that the engine needs to be rebuilt or replaced. Symptoms of excessive blow-by including oil being pushed up into the air filter, out the dipstick, or out the PCV valve and into the intake manifold where they could solidify on the intake ports and cause the valves to improperly seal over time.

The front valve allows the gases to pass into the intake tract only when there is vacuum present there(in the intake manifold). The valve closes/recirculates the gases when boost is present. The positive pressure from boost actually closes the valve.

Stock front PCV housing(labeled)

For a detailed diagram of how the system works, open the VW documentation below... (The PCV valve is called the "one-way valve" or "non-return valve" in the "pressure control valve housing" on page 8 in the "The 2.0L FSI Turbocharged Engine Design and Function" document.)

The PCV valve should only allow air to flow from the crankcase into the intake manifold when it is working properly. Since the air in the intake can be pressurized by the turbocharger, the PCV valve prevents the pressurized intake charge ("under boost") to enter the crankcase. If the PCV fails, the pressurized intake charge will leak into the crankcase, resulting in loss of boost pressure and hence power.It can also force the gases out the rear PCV into the turbo. This is why with some PCV failures oil is found in the compressor housing,outlet pipe, and intercooler piping.

Current remedies

Obtain the latest revision of the valve from VW

    http://forums.vwvortex.com/zerothread?id=3573586&page=2

Eurojet makes a replacement tube for the front which adds a heavy duty check valve.

    http://www.20squared.com/catalog/product_info.php?products_id=379

OR

A new amazing solution from BSH.

      http://www.bshspeedshop.com/store/product.php?productid=16937&cat=1011&page=1

Details and Discussion on this product...

       http://www.golfmkv.com/forums/showthread.php?t=58465

and here..

       http://forums.vwvortex.com/zerothread?id=3968872

To see which PCV version you have

The PCV valve has an embossed part number on its underside. Put a small mirror, perhaps a dental mirror, under the valve to see the part number.

To check for a faulty PCV valve

1. Method 1: look for signs of oil being blown out the oil filler cap: if the PCV valve is faulty, it will allow pressurized intake air back into the valve cover/crankcase. That pressurized air will then blow out any openings, such as the oil filler cap, or
2. Method 2 [vwvortex]: take off your engine cover and look for an accordion hose running from the intake manifold to the crank case. Disconnect the hose, clean off any oil with a rag, and blow through it from the intake manifold side. If very little air goes through, the PCV valve is fine. If air goes right through like there isn't even a valve there, it's shot.

Fix

Install a McMaster-Carr (part number: 1424T37) one-way check valve between the intake manifold and the OEM PCV valve.

The valve can either be installed in-line, in the hose between the OEM PCV valve and the intake manifold.

That hose can be replaced with silicone hose.

Another fix

Use pieces of 5/8" heater hose with 90 degree bends.

Another fix

"The new OEM "G" version of the PCV valve only has ONE check-valve in it. The one check-valve is a beefier valve to replace the one between the intake and valvecover. The second check-valve (between the turbo and valvecover) was moved to the hose between the turbo and valvecover." [vwvortex]

To do this fix, you will need the following OEM parts:

• 06F 129 101 G New breather ('PCV') valve
• 06F 103 215 A New pipe with checkvalve
• 06F 103 483 E Gasket