How to: Fix your NLA PCV Valve with modern replacement parts

[Cap10323]

Reposted due to a mistake in the first posting, and to add additional information.

This is my attempt at condensing 15+ pages of multiple 10-15 year old threads into one comprehensive guide, to hopefully help out some folks in the future.

Major kudos to SGKent, and Ray Greenwood for their extensive research and discussion of this problem in this great thread, as well as Metahacker, Wildthings, Air_Cooled_Nut and many others. Without their research, posts and photos I couldn't have compiled any of this, or made any of my badly drawn diagrams. 

~

As our busses age, a constant problem is parts becoming NLA. One such part is the PCV (Positive Crankcase Ventilation) valve, which regulates the release of crankcase gasses into the intake of the engine, as well as the amount of pressure within the crankcase while the engine is running.

Photo Credit: SGKent

How to test if your breather is bad:

There are two ways the breather can fail. Most commonly, the diaphragm within gets brittle with age and fails, which causes it to stop regulating the flow of gasses. This can lead to too much pressure building up inside the crankcase, which causes oil leaks/oil burning. Or too much vacuum being applied to the crankcase, which can cause oil consumption.

Photo Credit: Air_Cooled_Nut

To test your diaphragm, apply vacuum to the small vent hole on the top of the valve, block off the hole, and see if it holds vacuum. The easiest way to do this is just by sucking with your mouth, and blocking off the hole with your tongue. If it doesn't hold vacuum, or if you can suck large amounts of air through the hole, the diaphragm is bad.

Photo Credit: nick9

The other way the breather can fail is if the small hole, or passage inside becomes blocked with sludge or debris. One way to test for this is just to put the hose fitting end of the valve up to your mouth and suck, but you may get a mouthful of nasty surprises. Maybe use a piece of hose, or cover the opening with a rag while you do this.

Another way to test is by pulling the dipstick out slightly while the engine is running. If crankcase gasses come visibly blowing out of the dipstick tube, the breather is likely clogged causing a buildup of pressure in the crankcase. You could also check the crankcase pressure using a vacuum/pressure gauge, if you have one.


Unfortunately, you cannot buy a new replacement original valve, and due to the nature of rubber, any NOS valves you buy will likely already be bad, or are likely to fail very quickly.

Luckily, there's a solution. VW/Audi still uses a very similar part on modern vehicles, and it's very easy to adapt it to fit our busses.


Replacing the Valve:

You need:
• V.A.G P/N: 06A 129 101D (available through RockAuto, Amazon, FCPEuro, etc)
• A 7/8" (or 22mm) Rubber grommet (available from McMaster Carr, Amazon, Etc) Viton is best, but plain old rubber is fine IMO. This is such a tight fit, I am not overly concerned about a leak forming if the rubber hardens from heat.
• One tie-rap/ziptie/whatever you call it
• A new breather chest gasket (suggested)

The replacement process is very easy:

Take off your old breather, which is held on using two 10mm nuts and washers. I just put the nuts/washers back on the studs, where they can happily remain forever.
Make sure to also remove the O-Ring from the top of the breather chest if it stays behind when you remove the valve, as this will make it impossible to install the grommet later.

Then, press your 7/8" grommet over the hose fitting marked "K" on the new PCV valve. This is a little bit difficult, I recommend using a snap ring pliers to spread the grommet if you're having trouble.

Once installed, it should look like this:

Next, set the valve/grommet into the hole in the top of the breather chest, and using a small screwdriver, gently press one half of the split grommet down into the hole, so the thin lip of the breather chest is tightly sealed by both halves of the grommet.

This is by far the most difficult part of the job, as it's hard to see what you are doing. My suggestion is to flip the breather chest over periodically and look from underneath. This will let you see how much of the grommet has come through the hole.

Once the grommet is fully seated, you can go ahead and re-install the breather chest, complete with new valve, onto your engine. I suggest replacing the cork gasket that goes between the chest and block, but you don't strictly have to if yours is in good condition.

Lastly, reconnect the original intake hose to the new valve. If you find the hose is a little loose, you can trim down the stretched out part, and/or add a tie-rap to squeeze it down. I don't recommend using a hose clamp, as you will crack the plastic hose fitting on the valve if you over tighten it.

Your finished PCV valve upgrade should look like this:

Pretty close to a factory look.

Out of curiosity, I tested crankcase vacuum with the new and old valves installed. My old valve was bad, the diaphragm had failed and it had turned my crankcase into a huge vacuum chamber.

With the new valve installed, there is no detectable vacuum or pressure in the crankcase throughout the rev-range, hot or cold.

Just a very light fluttering of the gauge at idle, as the valve operates as intended.

I do not live in a very strict emissions state, but I suspect this fix should be smog compatible. Since you can prove it's essentially an updated version of the same part, with the same functionality.


Happy bussing!
_________________
-Ian

'77 Westfalia - 2.0 F.I

[Cap10323]

Also, full disclaimer since some feathers were ruffled the first time around.

No. I did not "invent" this solution. Nor did I claim to. As I said, this post is designed to act as a repository of information. Mainly gathered by other people.

That's why I made sure the first paragraph of the post is a thanks to everybody who took the time to research and document this issue. All photos are also credited.

I spent hours reading threads from 2007, 2009, etc. Which many greener Samba members may not know how to find, or know how to extract the useful info from pages of back and forth discussion.

I had to replace my PCV Valve anyway, so I figured I could take pictures outlining the process, and add them to a thread with the most important information from the 5+ threads I read through. Written in a way that was easy for someone who isn't as proficient at reading jargon to understand.


If you think the post is stupid, or it's already been said, well... nobody is forcing you to look at it! But you're welcome to link it to the next person who asks how to replace their PCV Valve, and save your fingers typing out the "already been said" information a 47th time.
_________________
-Ian

'77 Westfalia - 2.0 F.I

[Jetfxr69]

thanks again for this. the “cheap” version I bought has no small hole in the top. not sure how its gonna work if it cant feel ambient pressure against the diaphragm.
_________________
You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer. Zappa

‘77 westy Seamus
‘76 tintop Crusher
‘77 westy The Judge
‘72 tintop bastard westy Hudson

[AshC]

[Cap10323]

[SGKent]

Do you see the small hole in this photo? That is the side of the diaphragm that is open to the outside air. Crankcase gasses are on the other side of the diaphragm. If the diaphragm is perforated, the small hole will not hold a vacuum.

_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Cap10323]

Sarge,
The hole in question is on the replacement valve. Which does not have a hole on the top like the original, and instead has it located underneath the rim, opposing the inlet.

_________________
-Ian

'77 Westfalia - 2.0 F.I

[Jetfxr69]

copy. thanks for that pic. just found it on mine and confirmed with a blow/suck test. insert jokes here.
_________________
You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer. Zappa

‘77 westy Seamus
‘76 tintop Crusher
‘77 westy The Judge
‘72 tintop bastard westy Hudson

[SGKent]

it is Steve not Sarge.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Cap10323]

[SGKent]

[dodger tom]

may have missed it, but is the 7/8" dimension of the grommet outside diameter (i assume). happen to know what the i.d. is?
_________________
1978 Champaign Edition Westfalia
Would never find the time to keep up another classic air-cooled.

[Cap10323]

7/8 is the inner diameter.
_________________
-Ian

'77 Westfalia - 2.0 F.I

[andrewtf]

I would like to add my experience in attempting to fabricate this 'part'.

I could not for the life of me get the grommet seated in the breather chest. I ruined two grommets in the process. As sort of a last resort, I installed the grommet separately and then got the valve into the grommet. To facilitate the push thru the grommet, I warmed it up a bit with my heat gun. I then put a socket on the 'inside' of the breather chest to hold the perimeter edges of the grommet in place as I seated the valve and not just push the entire thing thru the hole. It was still a hefty push to seat it - but it worked.

Perhaps this will help someone else giving this a try.

I would imagine there is a fair bit of variation in a grommet's pliability and 'slippery-ness'.
_________________
'75 Riviera - 'BIG EMMA' (Pan American highway trip paused for a make over)
'77 Riviera - Murphy' (being reborn.... slowly)
'63 Austin Healey

[Cap10323]

[Amskeptic]

[Wildthings]

Watercooled Vanagons tend to run fine with a failed breather diaphragm, especially the 2.1L Digifant fueled ones. The Digfant ones have a 6mm restriction in the breather hose which I believe is designed to keep pulses from the crankcase from reaching the AFM and causing erratic readings. I have wondered what would happen if someone just took the Bay setup with a blown breather and just put a 6mm restriction in the hose.

[raygreenwood]

[Cap10323]

[SGKent]

the L-jet gets weird surges as the case acts like a huge vacuum can if the PCV is bad. It also allows air to be pulled thru the case if there are any leaks. The problem with a metered solution is that it will have to be changed as the amount of blowby varies.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin