So how does this system work? Review these first two graphics from the factory repair manual to find out.

(PS I wonder why the forced induction guys dont't use the air from the fan housing to spin their turbos? )

Then as a test, whats wrong with the charcoal conister installation on these diagrams? The first one is in the factory repair and Service and Training Manuals.

When you are done with this I have more...

They both show the air from the fan shroud go into the wrong end on the canister ...


The pressure side on the canister is on the side with the two nipples. Fresh air and vapors come in from the same side. The vapor/air mix is then expelled on the drivers side of the canister and routed to the engine air-filter housing ...


What do i win?
Andy

Jahvol Mein Freund

Win? HA! This is a documentary...

But wait there is more. The later plastic case charcoal canisters can be opened up and the activated charcoal can be replaced (check Google for suppliers). This should be done...every 50K miles according to the repair manual.

Jeff, you know you had to open a "can 'o worms" here.

What about the older cars? I was told by the local PD (dealer) in about '75/76 that the canister was self healing, in that it would clear itself & rejuvinate itself over time - like I believed that!

Charcoal has limited capabilities of absorbing hydrocarbons. Yes, it works fine for a few yeas of normal driving, but then it becomes, in the case of these pellets. over absorbed.. I suppose after that some " parked time" the pellets could clear of hydrocarbons, but would then absorb ambient moisture. Bad? Not certain, but I think so. And, when that moisture is released to the chamber & tank, corroson might occur.

Now, I seem to remember that there was a maintenance bulletin that recommended changing the canister on the early cars at around 50K. By that time (one my 914) they were unavailable.

So, given that my 914 is 37 years old, and isn't required to have emission testing in PA, would I be better off bypassing the canister? Is it of any value at this point?
Pat

Well Pat...

You can see the factory manual recomendaiton above indicating replacement at 50K intervals. Thats all I know. I dunno nuthin' 'bout the mineralogical properties of the activated charcoal, bet Google knows.

I believe its primarily an emissions thing...filtering raw hydrocarbons from the air (the fuel tank is not pressurized, its open to the atmosphere). If people smell gas in their cabins, it must be a faulty hose, loaded-up charcoal canister or some other flaw in the system.

OR, you could find an NOS charcoal canister correct for your model year...OR you could locate a later-issue <gasp> plastic canister and change out the charcoal as in the above picture.

Next chance I get I will post photos of the different styles of canister and their different locations...

How many different canister styles were their? How many different mounting locations?

How many different canister styles were their? How many different mounting locations?

A 1970 model

VIN 4712908458

VIN 4722907659

VIN 4732903509

VIN 4732914926

VIN 4732926371

VIN 4742905929

VIN 4742915964

From the 1975 Service and Training Manual

VIN 4752903075

VIN 4762901268

When i removed mine ('70 914-4), i opened it up to have a look inside. It was empty!

I guess after 30+ years, all the charcoal inside had turned to dust and was happily burned by my engine ...
Andy

FWIW; this is the only suitable place I could find on my '74 1.8 (VIN 7173). There were no holes in the left side body to bring the lines forward from the shroud/air cleaner, and the car did have the 5mm plastic line in the tunnel. Result? No fuel smell at all in the car or garage.

That is so funny! But probably true. Think I'll open mine up & see what's in there!

Not all 914s had a charcoal canister. This, from an early '70/4......

the '70/4 is a 49 state car, built date 01/1970

This is a great thread. Can somebody please confirm if the same system was used on the -6 models? (I've looked, and I can't find a definitive answer.) Thanks.

- MR

so can someone tell me where to pick up new charcoal for the system?
Thanks

Nope.

Me too!

I don't run one on the BB, but I'm sure my wife's car needs the charcoal replaced

I don't think you need the charcoal Pat, since your car hasn't run in, what, 15 years? But if you really would like some charcoal, maybe your local WaWa might have some.

It's only been 7 years! I've told you a million times not to exaggerate. And, don't you dare denigrate my WAWA (not the George Harrison variety).

there's no need to spend what seems like a small fortune on a couple of pounds of pellets. i found them at amazon. be careful of the small line fitting while opening and closing the canister. with carbs and the stock rear firewall location there will be fitment issue. you'll need to drill a small hole closer to the centerline of the engine to accommodate a bolt (same size as the stock mounting stud) for the bracket.

Does it matter if it's installed at the fuel tank, or in the engine compartment?

Where's the better (most efficient) location?

pretty sure the line locations and the lengths will dictate placement. on the 74' i'm working on, the small plastic line to the canister from the tank runs to the engine compartment thru the center tunnel (i think). its long enough to run to the stock rear firewall mounting point. the large line (single) from the port on the fan shroud (pass side) is in the engine compartment. the canister is the plastic version. trying to replicate the stock setup and to determine exactly how to use the carbs to draw off the vapors. i'll post some pictures later.

the canister, metal, on my 73' would be mounted on the fuel tank with the 2 long shroud lines running under the dr side rocker and a short small line to the nipple on the canister from the tank.

The 'BB' is a '75 and the small diameter hose is still there, so It would probably be best to find a good location in the engine bay

i just removed the canister from my 911sc since the hoses were shot and the removable end just about removed itself. probrobly empty by now im going to open it up and see. But im thinking is the canister there just for when the car is turned off and the fumes have a place to collect? because when its running it suckes the fumes in anyway and it doesnt get to the atmosphere. So by that theory i can bypass the canister and still plumb the lines to the intake and the fumes will just pool in the intake instead. potentially causing a big backfire when started perhaps. so would i be better off venting it to the atmosphere or leaving it plumbed to the intake. Im not real woried about smelling fumes but id rather not blow my airbox.

Before I saw your post I was thinking the same thing. However you bring up a good point.

David

I'd like to set the record straight here it's only been 10 years. Naberhaus, you are sooo negative. Relax, take lessons from me. It's not WHEN it runs, it's HOW it runs. Rome wasn't built in a day.

I just bought some on amazon. $10 for a 3lb bag. Hopefully the canister can be serviced on a '71

So it appears that almost any pet supply store should carry it

Will a 3lb bag do the trick?

Yes. Saigon did his and measured 1.7lbs in the canister.

i tried all of the pet stores, both big chain and independents, in my area before i looked at amazon. the pet stores didn't offer the activated charcoal in PELLETIZED form. all i found were expensive big clunky chunks.

http://www.thesamba.com/vw/forum/viewtopic.php?t=389074

Cool. Great link, Geoff

Any pictures of how the band that goes around the canister, mounts to the channel on the gas tank?

Our local fish store (yes, we still have one) has the pelletized form. Enough for 2 fillings.

Do you have a UPC from the package of pellets, or at least a brand name to look for?
BTW, I weighed the pellets I removed from a plastic unit, and it was exactly 800 grams. Or 1.8 lbs.

@davep . I got Acurel Extreme Activated Carbon Pellets. 45oz. Www.acurel.com. I think it was $24.99 or so. Clearly enough for two fillings.

Lets keep this going
Since so many cars have been converted to carburators it only makes sense to address
how if at all you can still use the evaporative system?
I know many people complain about the fuel smell that can permiate thier garage after
putting away thier carb'd car.
What is the best way to plumb the motor to lessen that effect? Is there one?

Edit : whoops! i didnt notice this was in the Originality sub!

Wow, an 11 year old thread! Jeff had a lot of time on his hands in 2010. I'm trying to put my 74 BB back to as original as possible and it came without a canister or hoses or a bracket. I now have a bracket but I'm wondering if finding a canister is going to be as difficult as finding an AAR valve.

That's what my mounting tab looks like. I'm wondering if I have the wrong canister, with the band that goes around the canister, don't make sense for attaching the two together??