Type 4 Oil Breather Pressure Regulating Valve 022 115 303 A

[nick9]

The breather box on top of the engine, has a fitting attached that has hose coming out of the side and a round, flat top. Is this supposed to act like a PCV valve? Or is it supposed to just filter out oil for crankcase ventilation? Does anyone have any information on these? I don't find much about these in Bentley.

Maybe someone has cut one open, seen inside, and has pictures?

[satchmo]

[[email protected]]

If you are so inclined to clean it out, you may be suprised how much crap you get out of there.
Best regards,
John
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luck is the result of good preperation

[nick9]

When I looked at manuals written in German language, it calls this part a "Druckregelventil" which translates in to "Pressure Control Valve". I guess this answers my old question. The MANN filter website says,"...pressure regulating valves ensure optimum pressure inside the crankcase. This prevents the escape of blow-by gases, and thus loss of oil at bearings and sealing points."

Sounds like an important part. (At idle, the valve would be closed and there would be no unmetered air being sucked in from crankcase fumes and leaks in the case?) Not a PCV valve but pressure regulating. I recently found out that there is discussion of these on the Vanagon/Eurovan forum. They have taken these, and the ones from their cars, apart, and there is a spring and diaphragm that is usually ruptured. They found that when this valve is broken, you get a rough, lean idle.

picture borrowed from that post

It is unfortunate that this part is NLA

[raygreenwood]

It is indeed a PCV valve and it does indeed regulate the pressure in the crankcase.

It is a crankcase vent. How it works...is its simplt a dipahram style PCV.

rebuild it without th eflexible diaphram and spring. many of us have found on type 4 engines in 411/412 and 914...that getting rid of any pulsing or intermittant style of PCV and going to a smaller but constant flow orifice....allows cleaner crankcase, constant metering of gasses..and less fluctuations in idle. It can work by allowing a constant measured amount of air by passing through it from the crankcase to the manifold. In this way it is not wide open to the manifold..causing an idle or open throttle situation. It gives plenty of air bypass to to keep crankcase gasses vented, has positive vacuum on those gasses via the intake manifold connection.....and above all...acts as an oil vapor seperator.

Simply put it back together with a solid metal or plastic plate in place of that spring loaded diaphram...with a 2-4mm hole drilled in it (you will need to find what size hole works for your engine...mine works with a 3mm hole).....and readjust idle and possibly idle mixture. Ray

[regis101]

So here is what i find, number wise.

= 3/16

.1574 = 4mm
.156 = 5/32 = 3.96mm

.118 = 3mm
.122 = 1/8 = 3.09mm

.0787 = 2mm
.0781 = 5/64 = 1.98mm

= 1/16

Doesn't take much. Makes me want to see if mines defective. Another one of those tuning issues, chasing gremlins. Who would think to check for a broken diaphragm
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Peace, Regis

[nick9]

Ray - Thank you for the information. Now that I know what to look for, I can see at least 2 tears in the diaphragm while shining a light inside. I am going to try to modify a spare.

Also, is this hole in the top normal, or did someone drill it? Isn't this what would be considered a vacuum leak. You can draw air through this tiny hole, from the 20mm outlet in the side even if you plug the bottom intake. It goes through the breather hose, right into the intake boot, past the AFM.

...and...

How about this hole in the bottom part? This is not a vacuum leak, but is just a direct path for crankcase air into the breather hose. Maybe I can just fill in the area to the side and leave this hole as the 3mm hole suggested?

It's one of those things that would be easy if they just still made the part. I've been looking at this for 15 years thinking that it must be replaceable. Every VW repair shop or dealer says it isn't a valve. I finally decided to really look into it, and it turns out it is a valve. One that must have been purposeful enough to include in the original design, but whatever... these cars are "obsolete". Time to improvise, adapt, overcome...
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Improvise, adapt, overcome.

[obieoberstar]

didn't the early type 4 buses have a breather cover that simply had a small pipe coming off of it as opposed the the plastic valve assembly?

definitely more reliable than the NLA valve in the long run.

[Air_Cooled_Nut]

[Wildthings]

There was a pretty good discussion of what these things do on the Vanagon forum a while back. They seem to do nothing but cause a small pressure buildup in the crankcase. They don't seem to function as a backfire preventer which is what I had thought they might be. I replaced the failed one on my beater 83 1/2 Vanagon and could tell no difference what so ever in how the engine idled or ran, or in the oil usage.

There were actually several types of breathers used on T4 engines. The D-jet motors had an actual PCV valve and vented rocker boxes, while the carburated engines just had a open box which maybe functioned as a baffle (this sounds like what nick9 asked about). The L-jet engines had the back pressure valve at issue here.

There were also a couple of European variant I have just seen pictures of.

If you have the common L-jet style valve and it is actually working 100%, I am not sure you should try Ray's idea. You might get a strong vacuum drawn in the crankcase under idle and decel, which could suck in a valve cover gasket. If the diaphragm were blown out, as I suspect most are, then it wouldn't be an issue.

Also if the diaphragm has failed then it would make since to close off the hole in the top of the valve with silicone, as this would cause the entrance of unmetered air into the intake air system.

Lively discussion to follow?

[Evil Clown]

My 76 has been carb converted and have the same issue. A mechanic said to run a hose to the side of motor
I'm wanting back FI, but for now am thinking of this.

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CARRY ON

[Wildthings]

[Evil Clown]

[SGKent]

I am wondering if anyone has actually talked to VW on this? One sees replacement PCV valves all the time for cars from the 70's. If truly there is no superceeded number, (there is also that 39 000 60 917 number on it), then a replacement might be made. I have only one so I cannot take it apart to see how it works. But if it acts as a PCV valve, closing to a small metered orifice at idle and opening at throttle or back pressure, one might be able to make a simple baseplate with a hole in it capable of fitting a grommet and a PCV valve from a similar size motor, perhaps a Honda 2 liter or something like that which is readially available. Another question for someone who knows these, is the diaphram from the later VW's the same size and shape? If so could one buy a newer unit, cannabilise it then rebuild the old style valve with it, perhaps with some sort of device that held the top on and could be removed to replace the diaphram every few years? I cannot believe that VW failed to make ample replacements of these if they are PCV valves. Smog laws in that era required parts for 50,000 to 100,000 miles be available.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[regis101]

Similar. States that it is used

http://www.germansupply.com/home/customer/product.php?productid=16820&cat=&page=2
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Peace, Regis

[Evil Clown]

JBUGS has this one.
http://www.jbugs.com/store/merchant.mvc?Screen=PROD&Product_Code=8544&Category_Code=159
Maybe this should be sufficient.
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CARRY ON

[SGKent]

To anyone who has had one apart. (1) Does the spring sit above the diaphram? (2) does the center of the diaphram seal the top of where the tube enters the body?

If so then the small hole on the bottom allows the metering of blowby in the closed position. If pressure builts it would push the diaphram up and open the larger hole to allow a greater flow. The tiny hole on the top would be to allow the backside of the diaphram to vent to ambient pressure.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

[SGKent]

If these leak they could be a cause of poor performance and a ean burn. While the mixture could be adjusted to accmodate, the system would work better with these functioning. I also see the potential for the main body of the valve to remain closed thus causing the engine to build up pressure and push out oil. Even if the diaphram is not ruptured, it might be hardened with age and not move to allow blowby. If I can't find a way to test them or one that is NOS, I will certainly look to see if a plate can be built that would allow a standard PCV valve to be used in lieu of this valve. Of all the misc NLA items that I've encounter restoring my 1977, this is one that troubles me. Lean burn or excessive crankcase pressure can cause serious side-effects. I am somewhat surprised that it has taken so many years for the community to notice this issue.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[busman78]

SGKent, yes ignored in the bus community, but not in the Type 4 community. Over on ShopTalk Forums the PCV discussion has been going on for quite awhile. Excellent posts, lots of informatiion. If you think the info Ray posted here is good, you will find the some of his postings on STF outstanding.