PCV Valve Brand / Function

[Benjamis]

I bought a UROParts hockey puck of the same exact part number as the original VW one that I took off, and it doesn't fit into the valve cover grommet, the lip of it is fatter and also 27 thousandths wider in diameter, which is enough for it not to fit.

Anyone have luck with aftermarket, or is the pricey VW one a must?

 

[garciapiano]

Üro parts is straight hot garbage. Don’t buy anything from that brand. I believe the one I have was made by Elring or Febi.

 

[Mongler98]

I got rid of the puck ages ago. Lower ccv crank block off plate too. Just use a copper 3/4 street 90* with (street side fits nicly into the grommet) a pex male solder to barb in 3/4. Rubber hose or vinyl braided from pex fitting to the turbo intake pipe. Costs about $4. I highly suggest you add a $20 proper oil vapor catch can. I tapped a hole into the block off plate at the crank ¹/4 NPT and ran the bottom of the catch can to it to drain. The puck literally does nothing after a while.

 

[Steve Addy]

Obviously URO doesn't make anything, they just repackage what others make. Having said that it seems that they tend to pick the lowest possible quality available and I try to avoid them unless there are no other options.

I think my rear beam axle bushings I bought were URO. They have held up good, then again it was a new suspension when I installed them, which makes a difference. I may also have purchased a URO cooling system flange too at some point.

I would avoid them unless there's no other option for you.

Steve

 

[Benjamis]

I got rid of the puck ages ago. Lower ccv crank block off plate too. Just use a copper 3/4 street 90* with (street side fits nicly into the grommet) a pex male solder to barb in 3/4. Rubber hose or vinyl braided from pex fitting to the turbo intake pipe. Costs about $4. I highly suggest you add a $20 proper oil vapor catch can. I tapped a hole into the block off plate at the crank ¹/4 NPT and ran the bottom of the catch can to it to drain. The puck literally does nothing after a while.

Doesn't the puck regulate crankcase pressure? Pretty sure I have too high of pressure in there, looks like the pcv I have has a collapsed diaphragm. Getting leaks out of the 3 valve cover bolts, oil filler cap, and where the breather hose meets the puck, and where the hose from the puck meets the intake. Would sure like to add a catch can in there, it's on the list.

 

[Steve Addy]

Doesn't the puck regulate crankcase pressure? Pretty sure I have too high of pressure in there, looks like the pcv I have has a collapsed diaphragm. Getting leaks out of the 3 valve cover bolts, oil filler cap, and where the breather hose meets the puck, and where the hose from the puck meets the intake. Would sure like to add a catch can in there, it's on the list.

You might benefit from replacing the rubber bits for the valve cover hold downs, those get very stiff over time due to age and oil exposure.

I have replaced them on my cars.

Steve

 

[Mongler98]

The puck is just a bigger chamber that holds a medium that resembles a foam sponge like thing that tried to stop oil droplets from going past and only letting oil vapor going though. It does this for the lower beather hose and the upper valve cover area (obviously). The lower breather was added for some reason but it's not needed. There are other engines with this block that have them blocked off from factory. Most of it was all an emissions attempt by VW. I've been running it blocked off with high hp and high revs with no issues what so ever with no catch can. Just a pipe I described above.
It has nothing to do with regulating anything. It eventually let's oil droplets fly by, probably after a few 10tousand miles from factory. You're actually supposed to replace it with every oil change but it was never made an official service item when VW did emission compliance.
Just do what I said above. Or buy oem parts. The lower breather is $$$ and always leaks once disturbed.

 

[Benjamis]

The puck is just a bigger chamber that holds a medium that resembles a foam sponge like thing that tried to stop oil droplets from going past and only letting oil vapor going though. It does this for the lower beather hose and the upper valve cover area (obviously). The lower breather was added for some reason but it's not needed. There are other engines with this block that have them blocked off from factory. Most of it was all an emissions attempt by VW. I've been running it blocked off with high hp and high revs with no issues what so ever with no catch can. Just a pipe I described above.
It has nothing to do with regulating anything. It eventually let's oil droplets fly by, probably after a few 10tousand miles from factory. You're actually supposed to replace it with every oil change but it was never made an official service item when VW did emission compliance.
Just do what I said above. Or buy oem parts. The lower breather is $$$ and always leaks once disturbed.

So just to make sure, the puck I have has a spring loaded plastic piece in it that has a plastiicy-rubbery diaphragm sandwiched in between it that I believe holds air and does not absorb anything. Engine vacuum pulls the valve closed (to not let boost pressure into crankcase?). Crankcase pressure keeps the valve open to allow the vapors to go to the intake. Does it not?

The lower breather is simply a pipe, correct? I always thought it was an oil-return pipe, to let any oil that condenses in the puck to fall back in the engine, but do see they are sold as breather pipes. The first and last time I let a "VW specialist" work on my car, they put a block off plate on the block where the breather tube comes out, but left the breather tube in place, which they broke and so had a big crack in it, and oil would heavily leak to the ground from there - coming from nowhere else but the puck up top. I replaced the pipe (this was a few years ago now) with a cheap aftermarket one and it is still leak free, except now recently a drip forms where it connects to the puck, along with other areas starting to drip.

I like the idea of getting rid of the puck, just want to make sure and understand why. Thanks for the info.

 

[Benjamis]

My puck is part number 028 129 101 D

 

[Mongler98]

I dont see any vacuum lines or spring loaded anything on that part number. Looks identical ot my ahu. As I though you had as well.either way.

 

[Benjamis]

Yea there's no vacuum lines, and pictures won't show what's on the inside, but mine and also the UROParts one has the plastic valve, spring, and rubbery diaphragm in it. If you plug the two side holes and suck on the valve cover outlet, the valve closes, and when the 'vacuum' is released, the spring pushes the valve back to the top of the puck in open position. I figured that during boost, the engine pressure is negative (i think?) and the vacuum of negative pressure closes that valve so boost pressure does not pressurize the engine. I figured the purpose of the diaphragm is only to provide an air seal for the plastic valve. Compared to the new UROparts one that didn't fit, my diaphragm looks deflated and the valve operates slower, as in it does not respond as quickly to vacuum. I cleaned it out good and still the same.

I would think the AHU and 1Z would use the same one, and if you aren't using one and are not having pressure issues, I am intrigued. Would rather not drop $90+ on a new oem hockey puck.

 

[Mongler98]

Like I said, these blocks have many variations. But they all do the same thing basically.
I've cut mine open, just a filter like sponge inside. Can you post a picture? What is the part number of the part you removed?
If any of these engines had pucks that had a vacuum control, it would be regulated by something, these cars run on boost to the ECU. Vac is only for breaking and HVAC control and most of that is cables.
Vacuum on these has nothing to do with vacuum of the engine.
Maybe its ran on boost but that would not make any sense. I'm very curious what's going on and how its controlled. I've given my input and please. Take it with a grain of salt. I'm mostly fimilure with these engines but I'm just a hobbyist shade tree mechanic who knows too much for my own good.

 

[turbodieseldyke]

Vac is only for breaking and HVAC control

And EGR.

 

[Mongler98]

And EGR.

100% correct. how could i forget.
i have never heard of a 1z or AHU use any control via boost or vacuum for the CCV puck.
there could be a check valve in there, maybe its right for your engine but im still sceptical. I ran 32PSI on my set up and had basically the entire thing a dete other than the one pipe form the valve cover. never once had the dip stick pop out or leaks at the 3 bolts or the gasket. if its leaking like you say, there are other issues, put a washer under the bolts to make it compress a bit more. thin washers. that or replace the rubber parts. easy fix.

 

[Steve Addy]

My puck is part number 028 129 101 D

That's the correct part number, perhaps it's just that the URO branded version fits tight or the rubber mounting

 

[Benjamis]

I spent 20 minutes trying to get it to fit in there. I wanted it to fit, but it didn't. Was worried about breaking something. The OEM one fits in tight.

20201022_142539.jpg

• Benjamis
• Feb 3, 2021

20201022_142639.jpg

• Benjamis
• Feb 3, 2021

It might not look like much, but the URO lip is higher and is 27 thousandths of an inch wider, which is enough for it not to fit. I dunno, maybe my grommet is oversized, but the fact the OEM fits snug and does not leak says something. But I'll look into pulling it off and trying to get a picture of its innards.

 

[Mongler98]

Just heat up the rubber with a heat gun.

 

[Benjamis]

It would fit into the rubber but it would not squeeze through when it gets to the valve cover. I pulled the grommet off and could fit it fully into the grommet, but with the grommet installed, it will not squeeze through. I was pushing down the whole car trying to push it in. It's a piece of plastic though so I didn't want to break it. I already returned it, thankfully autozone accepted the return even though it was opened.

 

[Mongler98]

Next time use our vendors.

 

[Steve Addy]

I spent 20 minutes trying to get it to fit in there. I wanted it to fit, but it didn't. Was worried about breaking something. The OEM one fits in tight.

It might not look like much, but the URO lip is higher and is 27 thousandths of an inch wider, which is enough for it not to fit. I dunno, maybe my grommet is oversized, but the fact the OEM fits snug and does not leak says something. But I'll look into pulling it off and trying to get a picture of its innards.

It's a tight fit anyway even with the OEM, and if your grommet at the valve cover is old and hardened that would make it even worse, but that's one reason I don't really trust the URO stuff, the fit can be questionable.

Steve

 

[Benjamis]

Next time use our vendors.

Who's your vendors?

 

[Mongler98]

Who's your vendors?

Not mine, vendors here at our forums like ID parts and GAP (GERMAN AUTO PARTS) ECS tuning and so on. Plenty of good quality parts to be had. God forbid you have to do to a dealership, no serisoulh stay away from box stores like autozone ect...... for your VAG parts.

 

[Benjamis]

I saw the URO parts one on ECS tuning and saw that I could get it locally quicker and cheaper. Needless to say, lesson learned. Just didn't want to shell out $100 for one from the stealer, but that's what I ended up doing. By the way, I have found that you can ask for a best price from the stealers and often times they will give you a significantly lower price than what they first asked for. So I got a new hockey puck for $90 something after they asked for $120 something.

This was back in February actually. Before I put the new puck on, I pulled the valve cover, to realize that most of my leaks were from the valve cover nuts being bottomed out on the studs. I had never pulled the valve cover before, and the last people to touch it were the erroneously named Volksmasters in FL. I put an extra washer under each nut, and voila, it can be torqued down properly on the gasket. I put the new puck on and do not get oil leaking from the hoses going out of the puck.

The new puck was way more responsive than the old one. If you cover 2 holes, and pull a vacuum on the third, the valve will close. The old one was very slow to move. For the sake of science, I cut open the old one. So here you have it, the innards of my old $100 hockey puck.

20210615_132136.jpg

• Benjamis
• Jun 23, 2021

20210615_132150.jpg

• Benjamis
• Jun 23, 2021

20210615_132208.jpg

• Benjamis
• Jun 23, 2021

That little hole there is where air is pulled in to expand the diaphragm. I had already soaked the whole thing and cleaned it out the best I thought I could before destroying it, but there must be a clog deeper in there. The top cannot be removed without cutting.

Old diaphragm vs. New diaphragm.

20210210_133432.jpg

• Benjamis
• Jul 17, 2021

20210210_135031.jpg

• Benjamis
• Jul 17, 2021

There is no puncture anywhere on the old diaphragm, and it wasn't brittle, didn't seem to be anything wrong with it. All the diaphragm does is expand to close the valve on the center hole which goes to the intake, against the resistance of the spring. The spring was fine. I think it was just a semi-clogged hole, but would sure be hard to clean that one out.

The only thing that can move that valve is vacuum from the intake, valve cover, or crankcase.

 

[ToddA1]

What made you replace it? I’ve never replaced one...

-Todd

 

[Benjamis]

Well, the rear main seal made me replace it, or perhaps lack of understanding, or maybe it actually needed it, maybe all the above. Since I was putting in the rear main seal due to broken flywheel bolts, I wanted to make sure there was not an issue with crankcase pressure that would make the new seal leak. The old one had seepage at minimum. For all I know, the oil in the area helped loosen the flywheel bolts. I thought since there was oil coming out of the hose connections coming out of the pcv valve, and leaks elsewhere, that perhaps there was excess pressure and the valve was not working as it should. I could not start the engine to test pressure without a flywheel. Blowby was recently seen to be average and not excessive. I thought the diaphragm inside the pcv valve was deflated and had a hole in it or something, did not understand how the valve functioned. Either way, when I replaced it and put everything back together, I stopped getting oil leaking out the breather hose connection and the hose connection going into the intake. Also the oil filler cap was leaking. The cap went on tight and the gasket did not look worn at all. It was not replaced and it doesn't leak anymore.

Does anyone understand what the pcv valve is really doing and how important it is? The engineers no doubt put it there for a reason, but whether that reason is absolutely vital for proper functioning or not remains to be seen. What circumstances would cause sufficient vacuum to close the valve and block flow of crankcase vapors to the intake?

 

[garciapiano]

Interesting. Based on my understanding of how a diesel engine works, the crankcase would basically never be under vacuum as there is nothing to pull against. The turbo is pushing air into the engine, not the other way around... To echo the previous post, what occurrence would create a vacuum inside the crankcase of a TDI? It may be a fail-safe to prevent excessive oil from being pulled into the turbo in the instance that perhaps something blocks the primary intake. Who knows.

My theory (based on conjecture, not evidence) is that the PCV system is meant to help equalize pressure between the top and the bottom of the crankcase as the engine wears and produces more blow-by into the crankcase. The gas engines also have this PCV system in the same general places but accomplish the routing a little differently.

The TDI has a few major differences. One is the higher compression ratio. The other is the turbo – it can't drain oil properly with too much crankcase pressure. So they may have overengineered the PCV system with that in mind – perhaps that is why the lower crankcase vent is significantly larger than the upper one.

My personal experience? I deleted the lower vent with a block-off plate and went to the ALH puck solely on the valve cover, which resulted in considerably worse leaks all over my engine. Nothing broke, and I noticed no difference in the performance of the engine, but it sprung an intermediate seal leak and a camshaft seal leak. Both these seals were sealing correctly before the installation of the block-off. Can't prove that it was a causal link but it's odd that those coincided.

So I have concluded the extra venting is important, at least on my engine with 400,000mi+ on it I have returned it to the stock configuration for the time being.

 

[Steve Addy]

Like Todd I've never replaced one either. I don't actually know how you tell if they fail.

In the case of the ill fitting URO brand I'd probably use an emery cloth to reduce the size of the bulge since that's likely to be the obstruction.

URO branded parts aren't necessarily a problem, but they need to be scrutinized more closely because often I think the quality may be lacking. In this case it's just that fitment is not good, but is it ok inside? Maybe, maybe not.

For some things URO is the only route to go anymore; they are the most convenient repackager of B3/4 rear beam axle bushings and also the least expensive. And since others here have used them and it appears they last just as long as any, I've used them on several occasions without incident. Then again URO doesn't make anything so the actual origin of what they sell is unknown.

According to VW these CCV pucks are different for different engines, but why I don't know. Perhaps the spring inside is set to a different rate based on the engine?

Steve

 

[Benjamis]

Come to think of it, it is not vacuum per se that closes the valve, but lower pressure from one inlet compared to the other two. That is, a large difference in pressure. If the turbo is pulling air from the air box through the intake, the air flow passing the PCV-to-intake hose will create suction or a drop in pressure due to the Bernoulli effect. Perhaps during boost, the suction is sufficient relative to crankcase pressure to close the valve so that oil pressure stays within acceptable limits.

By default, the valve is open so that positive crankcase pressure and blowby gases vent into the intake. The valve can be fully open, fully closed, or anywhere in between, doesn't have to be day or night.

If the valve were stuck closed, which I can't imagine happening on this type, high revs would mean higher blowby and higher crankcase pressure with nowhere to vent except out the seals.

If it stays open or is gunked up and slow to respond, there could be periods of low pressure in the crankcase since the turbo is pulling the blowby out too quick, and the engine could implode. Ha. But how bad would that be? Periods of low pressure in the crankcase?
Maybe that's another reason why people get tons of oil in the intercooler. The valve is gunked up or not closing properly and there is insane suction during boost. The puck is also supposed to condense oil and let it drain back down the breather hose to the block. If there are moments of high suction and the valve is still open, the oil sitting in the puck gets sucked in the intake.

Would be interesting to know the maximum air speed velocity in the intake at various boost pressures and at idle, etc.. I suppose I could calculate that at some point but am out of time for now.