Type 4 Oil Breather Pressure Regulating Valve 022 115 303 A

[raygreenwood]

Thats kind of what I was getting at when I mentioned the leverage even a small amount of vacuum applies to a diaphram of that size. Its main detraction will probably be the burning of large quantities of oil...although teh breather covers on type 4's are pretty nice oil baffels. Ray

[SGKent]

a custom design might include a set of 914 valve covers plumbed with a flame trap, and a Mann Provent system with a check valve. It would not be stock but I believe it would be close enough that it would pass smog in smog states.
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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

[raygreenwood]

It very hard to properly plumb vents into teh valve covers in a type 4. Not much clearance. Its just as simple to drill out the provided bosses...even with heads on....and insert the rocker box breather tubes and hoses like stock. Leave the vent diaphram plumbed to the very low pressure boot and run the rocker box hoses to teh air cleaner just like a 1.7 or 2.0 914. Cleasnest ands coolest running set-up I have seen.

The bosses for the cooling tubes are cast into the heads. Ray

[Wildthings]

[WhirledTraveller]

Well this discussion got my curiousity up, so I went and took the breather off the bus and had a good look.

Happily, it seems my breather functions properly. (Must be one of the lucky few). When I suck on the top hole I can feel the valve move and it holds the suction. I can see some of the diaphragm with a flashlight and it looks intact, and I can blow through freely from either end.

However I don't have the drain hole / suction breaker that aircoolednut has. Despite the identical part numbers stamped on the top. Weird?

Also, I surprised that the "breather tower" is not more baffled. It's hard to see in this blurry photo, but it looks like oil can just go right through it.

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1977 Westy, Automatic. Big Valve heads, CS Cam.

[josh]

[busman78]

Ray, in response to this thread along with the ones on STF I installed a metered flow PCV bleed direct to the intake manifold today. My valve covers were already vented with filters tucked away in the engine compartment. Drilled a 1/2" brass rod with a #31 drill (.120), which is just a hair over 3mm, installed a tee about three inches from the manifold in the brake booster line.

Wow! The improvement was noticable immediately, the engine steadied to a smooth idle, although a bit fast. Had to increase the idle jet one step, turn the throttle setting down a half turn, sitting at 800rpm and steady. Besides the 3mm orifice I made a 4mm and 5mm which I have not played with yet. Did a quick blast down the interstate, after about twenty miles I pulled over and removed a plug, a really nice light chocolate milkshake color. Unfortunately the wind kicked up and clouds rolled in.

[SGKent]

That is super. You might look at a 914 breather box to see what size bleed is on it. From the appearance the 914 its breather box is slightly different and it does not appear to use the funky valve. One option I might consider is to use a wide band a/f gauge to set the bleed size. Are you using a pcv valve of any kind in line that shuts off at low vacuum?

Also - I seem to remember that in the Weber carbs, 3 air bleed jets is equal to 1 main jet. (best to look it up my memory is old). By playing with the air bleed vs main jet sizes, you can change the a/f curve, whether it favors enrichment at the low or top end. I believe that going up 1 on the main jet and up 3 sizes of airbleed will favor enrichment at the top end (best to look it up) while down 3 sizes of airbleed and down 1 on the main favors enrichment at the low end of the rpm curve.
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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, I used a 914 breather without that funky valve. Need to put a couple copper choreboys in the tower to help separate, although inspection of the bleed valve was dry. My top end and transition from progression to main is nice, secondary is superb, I did have a very slight, hard to put your finger on mid/high progression lag (stumble), on getting home I checked the float level and it was high, 36mm instead of 41mm, possibly flooding the emulsions with too much fuel. No chance to test. I will be pulling the carb to check the position of the primary thottle plate in relation to the first progression port, based on the response I have now from idle to progression I suspect the plate is right where it should be. Still going to test the 5mm & 6mm bleeds, I am sure there will be a little main or air correction change down the road but for now I am impressed.

On my list of things to buy is an A/F unit, for now it is a seat of the pants affair.

[SGKent]

the throttle plate placement on first progression hole will make a significant difference in coming off idle. Some webers are have a thin bevel there so the width of the throttle plate is less and that makes it easier to match up the first progression hole. I also hold the throttle body up to light to be sure the throttle plates are even in the bore. Locktight or lightly peen the bolts if you loosen them. Once adjusted rarely do they even need it again unless the throttle bushing wears from the shaft.

You indicated a mid flat spot. That can also be the timing curve passing through a range and hesitating a little. I could always tell when the weights were getting a little dry or the plate needed a little lubriplate.

We have this 1977 we are restoring and in California it has to be smog legal to the year made. Carbs are so simple to tune compared to the 1977 FI - at least for me.
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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

[VDub Campers Ltd]

My breather diaphragm is totally shot. I removed it and sealed the top back on.
What's likely to happen if i run the bus like this?
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[SGKent]

the diaphragm moves constantly to regulate the pressure inside the case. I can feel small pulses of air on mine coming out the diaphragm hole and since the diaphragm is good it tells me that the diaphragm is really working hard to keep that pressure at -0- and no less.

Without a diaphragm you will apply a vacuum inside the case and that will cause more air to be sucked in and bypass the AFM. If you have a carb you can vent it to the air cleaner without worry. If you still have the FI, your choices are to either vent to a catch can and plug off the end that goes into S-boot (not smoggable), find a used one, spend $1200 to have a hundred diaphragms made, or build a metering contraption like Ray Greenwood suggests. My suggestion is to find a good used one until someone is willing to spend $1200 to have 100 made. I lack the money right now or I would do that. I've written Mann-Hummel twice and they don't respond so the odds of them making them again are nil.
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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]

There is a good thread on breathers on the Vanagon forum.

http://www.thesamba.com/vw/forum/viewtopic.php?t=295812

The consensus seems to be is that it makes little difference whether the diaphragm is good or not. If the diaphragm is bad you do need to make sure all the engine seals are in good condition as the case which originally was under a slight pressure will be under a slight vacuum. Unless you have air leaking into the case, the lack of properly working breather valve should not affect mixture as crankcase gases are pretty inert or at least neutral as to oxygen requirements.

[SGKent]

Just look for a good used one in the wrecking yards.

I have studied this valve pretty extensively. From the design, its purpose is most noticeable on a healthy engine. Assuming that blowby is tolerable, without it working correctly the vacuum in the S-boot will overcome the blowby and create a vacuum inside the case. This will increase blowby and any air leaks into the case. I may even suck in valve cover gaskets, and cause premature crankshaft seal failures by keeping the seals drier. Is it noticeable? Probably not in the short term but over time yes. If the oppisite is true - the engine is worn and has extensive blowby already - the case of the vanagon thread, adding or removing the valve does nothing because the blowby has already overcome the FI idle circuit and mixture. Good or bad, the blowby was already too much for the FI idle circuit to handle. Probably the owner has extensive blowby because he ran the engine too long with a bad valve. The vacuum in the case in its initial stages reduced lubrication on the rings and allowed for more ring wear. In effect the rings went through a life cycle very quickly because of the decrease in lubrication. Now the constant blowby makes it impossible for the owner to control the idle.

I will eventually have spare diaphragms made and sell them but not right now as I am still looking for a couple nos valves to use as the mold. If my current one went bad and I was unable to find a good used one, an alternative solution would be to create some sort of a filter/trap to catch the oil and work as a flame trap, then dump the blowby into the air cleaner. This solution worked well for carbs for 20 years. IMHO it would over time however gum up the AFM and lead to a failure there. How soon would depend upon how well the oil filter/trap was designed. But it is easier to replace an AFM than an engine.

There is a product that IMHO can easily be used to substitute for the valve but it would take some mounting to use it. It is also made by Mann-Hummel and is the newest generic valve designed to do what the one in our bus does.

www.mann-hummel.com/group/upload/doc/HBLAXUCmOK5.pdf

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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]

[Rusty O'Toole]

How about removing the broken diaphragm and substituting a conventional PCV valve in the hose?

[baumer99]

I recently replaced a shot breather with a working one. The shot one produced a constant stream of air, where the new (used) working one produced the pulses described:

[SGKent]

The part simply keeps the crankcase pressure from falling below whatever the outside airpressure is. A PCV valve kind of does the same thing by allowing more flow when the engine needs it and less at idle. If there is too much flow it goes out the air intake hose back to the air cleaner. For some reason Bosch chose not to use a PCV valve and went with a pressure regulator.

I thought that I could find another engine close to 2.0 with L-Jetronic FI and use their valve. Everything I looked at including Porsche was a variation of what we have and everything was NLA. The only thing I found close was that generic Mann-Hummel Provent valve.

My suspicion is that if the part was still available for the $15 it used to cost, the people who say ignore it would have new ones on their engines. Carbed engines can bow out now because you don't need it, you can just draft flow to the airbox or meter flow like the 914's did. I think we don't draft to the airbox because the oils would gum up the AFM.

Ray Greeenwood suggested using a metered hole for this but my concern is that at times the metering will not allow enough blowby to pass by and the engine will build up pressure internally.

The solution that I found easiest is to find good ones and set them aside for when the one I have fails. If they can't be come by then either make up diaphragms or use a provent.

I just wish someone would discover a box of them NOS and send me a few.
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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

[73kombi]

Having just read all 4 pages of this excellent thread...I would like your opinions on my ghetto fix for blow by. Yes my engine needs rings, and a few other things, but I was thinking a slight negative crankcase pressure would slow the oil leaks, and it has.

I am running a Holly/Weber on an 1800cc engine and made my own intake manifold pressure regulator. It started like this...

The 1/8" hole in the sink washer allowed way to much vacuum into the case, so I added this door panel push pin...designed to fail closed. MacGyver look out!

Mixed up the magic JB weld...

and installed it in the reducer...

Ok.....so I am running this direct to the manifold, and I would guess I am pulling <1lb vac on the case...the oil cap has a mild suction, and I enriched my my idle mix a little, but no other issues have arisen...timing advance seems the same.

It doesn't seem to effect highway driving at all, but I will have to check my plugs in a day or two. I washed the engine, (which was still leaking) and drove her about 60 hwy miles today...normally she would be seeping, but now clean and dry. Even my valve cover leak has stopped!
It's odd not to see the three oil stained marks under the bus.

I am considering adding a PCV valve into the mix...would you have any suggestions? Ideas? Are there any long term problems with running a mild negative case pressure?

I am considering adding valve cover vents into the mix too....like busman78 has. He has a different setup, but this kit is similar.

http://www.jbugs.com/product/8544.html?Category_Code=159

Great thread!