So why people buy a new PCV valve? --> PICS

[jackyaudi]

I took off my PCV valve and I thought about cleaning it so I dont buy a new one for $45 or so at the dealer. So I put some light inside it and from the pics it looks to me that its 100% cleanable.. Mine had LOTS of dried oil pieces inside that all went out when cleaned with water and alcohol mix. Also used Q-Tips with alcohol and it looked very clean inside afterward. Here are some pics inside the PCV (half-way cleaned):

[Capt. Obvious]

I just took mine out. [:P]

[[email protected]]

I think blasting it with brake cleaner would have been faster

[diagnosticator]

The proper name of this part is "Crankcase Pressure Regulation Valve". It's function is similar to, but not the same as a PCV valve used on many other cars. A PCV valve is usually a spring loaded variable restriction to control flow from the crankcase vapors into the intake manifold.
The CPRV, limits flow of the crankcase vapors also, but is referenced to outside ambient air pressure and controls vapor flow rate according to the difference between the crankcase pressure and the ambient outside air pressure.
Besides clogging, CPRV failure can develop from a stiff or cracked diaphragm inside from age and heat, resulting in a CPRV that can't react to small changes in pressure differentials involved.

[7speed]

The proper name of this part is "Crankcase Pressure Regulation Valve". It's function is similar to, but not the same as a PCV valve used on many other cars. A PCV valve is usually a spring loaded variable restriction to control flow from the crankcase vapors into the intake manifold.
The CPRV, limits flow of the crankcase vapors also, but is referenced to outside ambient air pressure and controls vapor flow rate according to the difference between the crankcase pressure and the ambient outside air pressure.
Besides clogging, CPRV failure can develop from a stiff or cracked diaphragm inside from age and heat, resulting in a CPRV that can't react to small changes in pressure differentials involved.

Your post are always full of great information ...... but they make my head hurt

[dougyfresh]

The proper name of this part is "Crankcase Pressure Regulation Valve". It's function is similar to, but not the same as a PCV valve used on many other cars. A PCV valve is usually a spring loaded variable restriction to control flow from the crankcase vapors into the intake manifold.
The CPRV, limits flow of the crankcase vapors also, but is referenced to outside ambient air pressure and controls vapor flow rate according to the difference between the crankcase pressure and the ambient outside air pressure.
Besides clogging, CPRV failure can develop from a stiff or cracked diaphragm inside from age and heat, resulting in a CPRV that can't react to small changes in pressure differentials involved.

If the CPRV is not working properly, that will cause an issue with venting the crankcase pressures. Correct?

[diagnosticator]

If the CPRV is not working properly, that will cause an issue with venting the crankcase pressures. Correct?

Yes, correct. The control action is lost therefore so is the maintenance of crankcase pressure slightly below ambient air pressure. The ventilation flow rate is effected by the engine load/blow-by volume. The CPRV adjusts to the load dependent blow-by occurring, to regulate the crankcase pressure. Depending on the flow state of the valve in failure mode, at low load, the ventilation can be excessive, pulling more than normal amounts of oil aerosols into the intake plumbing. (enough to noticeably increase lube oil consumption.) During higher load, the crankcase pressure can increase enough to cause external oil leaks too. During boost conditions, crankcase pressure will be slightly positive, but only on a temporary basis. The majority of street driving time is with no boost.

[diagnosticator]

Your post are always full of great information ...... but they make my head hurt

Yeah, by the time I click on "submit reply", my head frequently hurts too.

[dougyfresh]

Yes, correct. The control action is lost therefore so is the maintenance of crankcase pressure slightly below ambient air pressure. The ventilation flow rate is effected by the engine load/blow-by volume. The CPRV adjusts to the load dependent blow-by occurring, to regulate the crankcase pressure. Depending on the flow state of the valve in failure mode, at low load, the ventilation can be excessive, pulling more than normal amounts of oil aerosols into the intake plumbing. (enough to noticeably increase lube oil consumption.) During higher load, the crankcase pressure can increase enough to case external oil leaks too. During boost conditions, crankcase pressure will be slightly positive, but only on a temporary basis. The majority of street driving time is with no boost.

John,
Relative to this and your other post (thanks BTW), is there any way to test the CPRV and verify it is opening and closing under the proper loading?

The OP and I have been trying to trace down a phantom noise in his car. It appears to be coming from the EVAP system. When he disconnected (from the TIP) the line the CPRV is contained the noise disappears. When he puts his hand over the CRPV output the noise comes back (did I get that right?). This was done at idle I believe.

I am thinking either the CRPV or some check valve is not operating correctly and he is not able to vent the crankcase pressures appropriately.

[nickyreno]

I think blasting it with brake cleaner would have been faster

Word.

[diagnosticator]

From the description, my suspicion is with a check valve in the system somewhere. Normally, the CPRV won't be a noise source, the flow velocities involved are low, so any thing making enough noise to be noticed, would be from a high velocity flow device like a check valve in the EVAP system of maybe the Suction Jet Pump is involved here.
Regarding testing the CPRV, there is no direct test, the functional status is only evaluated by measuring the crankcase pressure, or if evidence of overpressure exists, etc. EDIT: If the diaphagm, accessed from the center bottom inlet port seems plyable when pressed with a dull pointed tool, it's likely in good condition, if no cracks can be seen. Also, if the inlet port is slightly pressurized with low pressure air, and the outlet port blocked, there should be NO air flow from the small vent hole in the top cover.

[jackyaudi]

Thanks Doug!

Well its like this: If we disconnect the tube connecting the CPRV to that solid line that runs all the way to the back of t he valve cover, we hear the noise clearly. If we then put a fingertip and block it, the noise goes away, as if blocking pressure to the CPRV is making the noise go away..

BTW, as far as the CPRV is concerned, John, I did not see anything really mechanical inside it, its just two holes one in the middle and one at the top I guess that controls how much pressure to go through the TIP. There is a spring in the middle, and it has a round design I guess to hold some of that pressure before passing it to the TIP at a certain rate. I could be wrong, but thats what it looks like from the inside. There is nothing in there that "opens" or "closes"

[jackyaudi]

From the description, my suspicion is with a check valve in the system somewhere. Normally, the CPRV won't be a noise source, the flow velocities involved are low, so any thing making enough noise to be noticed, would be from a high velocity flow device like a check valve in the EVAP system of maybe the Suction Jet Pump is involved here.
Regarding testing the CPRV, there is no direct test, the functional status is only evaluated by measuring the crankcase pressure, or if evidence of overpressure exists, etc. EDIT: If the diaphagm, accessed from the center bottom inlet port seems plyable when pressed with a dull pointed tool, it's likely in good condition, if no cracks can be seen. Also, if the inlet port is slightly pressurized with low pressure air, and the outlet port blocked, there should be NO air flow from the small vent hole in the top cover.

Thanks for the reply. IS there a way to test that breather valve under the intake manifold without really taking out so many things? Maybe by blocking another tube or valve on purpose and checking if the noise persists which would mean the breather valve is blocked?

I will go ahead and blow air through each check valve and see if they work fine. Am assuming all of them are one-way valves or is there any exceptions?

[diagnosticator]

There is a diaphragm inside located at the seam joint where the top cover and the valve housing are welded together, and the low tension spring you noted. That is why the body of the CPRV is shaped like it is, to house the flat diaphragm, and seal all around the edge, so that one side is exposed to ambient air pressure, while the other side is exposed to internal crankcase pressure. The pressure differential, opposes the spring force, to position the internal flow control valve according to the blow-by volume occurring, to regulate the crankcase pressure as blow-by flow rate varies with engine load. If you ever replace one of these, you can cut the seam and open on the old valve to see how it's put together. Actually, it is very similar to a diaphragm DV, but the valve element is special purpose to the application.

Check valves are always a One way flow device, that is the context of "check" as used here. A check valve can make funny noises is the valve flap inside is torn or if there is some other defect, allowing the internal part to vibrate like a reed and cause noises.
I am not sure how blocking the CPRV flow would effect the noise in your situation, but it's not hard to figure that doing that will change some pressure somewhere, that can effect the symptoms.

[dougyfresh]

Thanks John. We'll continue to do a check on the rest of the system to determine if any of the check valves or other valves are faulty. I think it is clear that we have narrowed his 'noise' issues to this system.

[diagnosticator]

Thanks for the reply. IS there a way to test that breather valve under the intake manifold without really taking out so many things? Maybe by blocking another tube or valve on purpose and checking if the noise persists which would mean the breather valve is blocked?

The fitting under the intake manifold, must be examined visually for blockage. Deposits are likely to exist in all of the crankcase ventilation system, as evidenced by the deposits found in the CPRV. It's a pain, but the hoses should be removed and cleaned or replaced with new hoses. New if the old hoses are hardened and subject to cracking.

[dougyfresh]

That fitting on the block breather is also prone to cracking. It is made out of plastic and becomes brittle over time with the heat cycles the engine sees. If you are removing it be careful for it could break. If it does break then parts could get down into the breather. Then you have to pull the oil filter, oil cooler and that whole assembly to get it off the block and clean it out.

[SixGear]

Quick question...
I have been having some weird and harsh problems with my B6 lately, been thinking its either the abs module or the tip tranny itself.
The car dosnt want to pull off right, sometimes clunks or stalls.
I cleaned out the throttle body, air temp sensor and the TB hose, and realigned the TB via Vag-com. She seems to be working ok now.

There was alot of oil residue on the TB and the TB hose. There is also alot of oil on the side of the SMIC.
The turbo only has 30k miles on it and feels/spools up fine.

You think my CVP needs replacing?

I'm pulling out my SMIC out today and cleaning it off.

[Frey7190]

Where is the PCV Valve located in the 3.0L?

[jackyaudi]

Thanks John. We'll continue to do a check on the rest of the system to determine if any of the check valves or other valves are faulty. I think it is clear that we have narrowed his 'noise' issues to this system.

Ok guys, some updates...

I found only 5 of the 6 check valves, cannot seem to find #2 in the pic below:




But ALL of the check-valves I checked are working fine. #5 was a PITA. I checked again today, and disconnecting the connection you see in the red line in the pic below is where the noise is very clear and kinda loud:



I have not checked the "T shaped" connection on the back of the valve cover (crankcase breather) nor that breather valve under the intake manifold. I mean whats the chances that this breather valve is blocked...

I ruled out the PCV because its all cleaned now and because the noise is happening before pressure reaches it.

What do you guys think I should check next??

[Mike02A4]

Did you notice anything after cleaning it? I'm going to do mine tomorrow with brake cleaner.

[jackyaudi]

Did you notice anything after cleaning it? I'm going to do mine tomorrow with brake cleaner.

Well, in my case I wont tell the difference even if there is one.. but I got a shit load of stuff out from that PCV/CPRV. And much of that stuff goes to the TIP and Turbo...

[jessefrank]

I also cleaned my "Crankcase Pressure Regulation Valve". I used brake cleaner at first, but found that getting some hot water and Dawn really cut through the grime and cleaned the best (I soaked it twice, but the first time got most if not all the stuff out).

I was having alot of oil blow-by around the oil fill cap. I figured I could clean it for free and see what happened. IMO it worked. No more blow-by and that was over 15k ago.

Also could have been a coinsidence, but my cam adjuster seal leak (back of engine) seemingly stopped afterward.

[SLeal]

Where is the PCV Valve located in the 3.0L?

Looking for the same info!!!

[Spirare]

Looking for the same info!!!

Same here. I'm actually looking for part numbers and a place to buy the pieces; suction pump, pipes, valves etc.
Also... what is the bit running over bank1 that starts where the dipstick is in the picture and covers the VC bolts? I'm seeing oil on my VC right under that piece. I'm just not familiar with the part and don't have bently for the 3.0L

Any help you guys could offer would be appreciated

[jacobsen]

So cleaning the PCV valve works? I have some zep degreaser or brake cleaner which one should I use? I guess brake cleaner would force it's way in better? But degreaser would probobly work better.

[customa4]

The valve in the original post is a PRV valve.

[jacobsen]

okay, the pcv in my case is a 3 way check valve looking thing which I've already replaced yet I'm not getting vacuum in my vc/crank case.

[xdewaynex]

Those with the 3.0, the entire pcv setup is on the rear of the engine under the plastic cover with the Audi rings. Its kind of a mess back there with the valve cover breathers, crankcase breather and sai lines. All of my lines were brittle and pretty much fell apart.