What to run to evaporation chamber

[stcj]

[Artistic gearhead]

Wow, that is complicated. Thanks for the info. I suspect that my simple hose replacement fix is not going to completely solve this issue. Looks like smog gear has been removed years ago so I will try to route a new vent pipe to atmosphere. With the recommended “shepherds crook”. Thankyou all.

[David Bunin]

Hello Forum,

I was referred to this thread from my "New Kid" posting, and I've found this very helpful. For those who don't care to read the other thread, I bought a 74 convertible from my Uncle and I've been tinkering with it to make it as close to 100% functional as I can achieve. Among other things, it has a fuel smell while driving (with the top down). This has made me think the problem is somewhere in front of the driver.

I found most (if not all) of the hoses forward of the dashboard as described here, particularly in the revised sketch at the end above. The most deteriorated one on my car appears to be the half-inch vent line from the tank to the fender, but to be fair I haven't explored how I might inspect inside the fender to the filler cap. The drawing suggests there's another hose that is out of my view in the trunk.

What I'm most puzzled about at the moment is the theory of operation for the expansion tank. As best I can see, mine has a small hose at the front face and another small hose on the rear face, and that's it. Neither hose is located at the bottom of the expansion tank, so neither one is going to drain liquid fuel out of it. How does fuel ever end up in there? If it does, how does it ever get out? If the expansion tank can be a trap for a quantity of fuel, what's the point of it?

David

P.S. Edit: I looked inside the fender, and found that the rest of the filler assembly is visible right there. I also think I see where my fuel leak is coming from. There appears to be a dribble coming from where the metal section of the vent tube penetrates the fender wall, on the wheel side. If the leak is from the metal section rather than any of the rubber hoses, that might be "above my pay grade" and worthy of a visit to a legitimate shop. I think the immediate solution (and this was probably Uncle Nelson's solution too) is to simply not fill the car up with gas in the interim.

P.P.S. Edit: I looked again, and maybe the "blue" line is connected near the bottom of the expansion tank, but on my car this hose route up and over the top of the tank at the outboard edge. Maybe it's supposed to bend the other way and run under the tank back to the Tee fitting? Still, that only takes liquid fuel to the tee fitting. Then what?

[jeffrey8164]

Nothing to be afraid of here.
The metal pipe that passes through is just that. A metal pipe. It’s simply held in place by rubber grommets. While a little finicky, I don’t remember it being that big a deal. Just make sure you really have to do it first. When I replaced those grommets the pipe was in fine shape.
Leaking liquid will take the path of least resistance so, where you see it might not be where it’s coming from. I don’t know when or if any of the filler neck hose and gaskets have been replaced or any of the breather lines so any or all of them could have some deterioration going on.
_________________
Volkswagen!
Turning owners into mechanics since 1938.

“Let he that is without oil throw the first rod”
(Compression 8.7:1)

[jeffrey8164]

These are important.

This is how I routed my breather.
I did delete the expansion tank and charcoal canister from mine to simplify things.
_________________
Volkswagen!
Turning owners into mechanics since 1938.

“Let he that is without oil throw the first rod”
(Compression 8.7:1)

[David Bunin]

[jeffrey8164]

That hose is definitely crusty.
_________________
Volkswagen!
Turning owners into mechanics since 1938.

“Let he that is without oil throw the first rod”
(Compression 8.7:1)

[22manybugs]

The hose circled in red looks like it has the original crimp clamps, so that hose is probably 50+ years old and is almost for sure a problem. The gas trail is probably from the rubber hose leaking, then the gas runs down the metal hose and down the inside fender. I doubt the metal hose is the problem.

When I replaced that hose on my car, it was impossible to bend the replacement hose 90 degrees without kinking it. It might work okay even with the kink, but there is a 90-degree elbow that you can buy as an alternate: https://airheadparts.com/vw-part/fuel-filler-overflow-elbow-141-201-179/

There should be a small nipple on the other side of the fuel filler neck, it should be visible in the area circled in blue. I don't see it in the photo. Normal diameter vapor line (3.5mm?) attaches to that and goes to another metal pass-through to the inside of the trunk. (That is shown as the orange vapor line in the above emission sketch). That line is easy to miss so it often gets overlooked (ask me how I know ), it can also be bad and cause gas smells. Do you have another small vapor line connected in that area?

What is the area circled in green? I can't tell. Is it just a shadow or an opening to the fuel system? I am asking because I can't see the line on the other side, so wondering if on '74s maybe VW moved the small line to the same side as the larger line, and you are missing the small vapor line. If it is an opening to the fuel system, that definitely needs to be plugged.
_________________
Lon

1969 Karmann Ghia convertible
1971 Westfalia camper

[David Bunin]

The one you've circled in green is the "orange" line from the diagram. I'll try to back up and get a wider view here:

The fellow who runs the 1974 Ghia Registry reached out to tell me that my car is one of the newer ones to come off the production line. I'll guess (as you did) that they made a design change and moved the small vent line around to the front to Tee in with the main vent line. The hose routing supports that notion. Replacing that hose (particularly getting a new clamp on it) would/will be a challenge at the unseen end where it passes into the trunk wall.

The 90° bend that you gave the link to, is that a rubber hose or a black metal tube? I can't tell from the description or the picture. They describe it as an overflow elbow, which is a metal tube that is also visible in my image above. (Goes nowhere, open end.)

[22manybugs]

[David Bunin]

Ok, I'm convinced enough that I'm ordering the right part. I've bought the 90° elbow.

I'm going to buy a bunch of the small diameter fuel hose locally to replace the vent lines. I agree the vent hose in this image looks deteriorated, and maybe that's the case, but also notice that this area of the fender has been sprayed with something (underbody coating?) and there's plenty of that on the hose contributing (perhaps unfairly) to a deteriorated appearance. When I touched it, it was still surprisingly supple and flexible. But as noted above, probably still not happy with modern ethanol-infused fuels.

We'll see how bad it really was after I've replaced it.

[David Bunin]

Here's a question that I felt sure would have been answered already in the conversation above, but I don't see it. Where do you guys buy the 1/8" (3.5mm) hose from?

I thought it would be an easy "get" from any local auto parts store, but invariably when I asked for 1/8" fuel hose they all said, "Like for a weed-wacker or a chainsaw?" or "Like for an RC model?"

I could (and probably should) just remove one of the hoses from the car and take it in to show them, but at the moment it's still drivable. In fact, as the fuel level has gone down so has the fuel smell, which supports the notion that the vent lines are the source of the problem.

I did find small fuel line at NAPA but it looks very different from what's on the car. I found something on Amazon that looks right, but I thought I'd ask you guys for your favorite supplier before I shop blindly online.

I'm not interested in spending much extra for some hose made in Germany. I want the car to be safe on the road. This is maintenance, not a restoration. At the same time, I'm not impressed with the soft hose that NAPA had that looks very different from the original, and makes me think that while it might work, it probably isn't right.

Also, once I have a source, how much do I need? Three meters? Four? I presume I'll end up replacing every original hose.

[dingerjunkie]

Okay...my project doesn't have the expansion chamber, canister or any of the lines present. Searches aren't coming up with appropriate parts, here in classifieds or through the usual marketplaces.

Any non-stock analogues people can share, or examples of modified plumbing for direct-to-atmosphere venting with a filter?

[David Bunin]

One local shop asked if I could use "vacuum hose" which (they reasoned) must be at least fuel tolerant, even if it's not actually rated as fuel hose.

Again, I'm not looking for perfect authenticity. I am looking for a material that is fit-for-purpose.

[22manybugs]

I went through the same discussion. Local stores didn't have fuel line that small and would suggest "vacuum line", but none of the vacuum line packaging stated that it was fuel resistant. I finally used some small-diameter fuel hose from Amazon.

That was 1 or 2 years ago. I just checked Amazon and the fuel line I bought is not available, so you would have to search to see what's available now.

Below is one from Amazon (not the one I used). 1/8" diameter seems pretty small but maybe it will fit, I think I used one size bigger. If you are replacing all the vapor lines, 6 feet is not enough, you would need at least two packs (12 feet). Maybe even 3 packs (18 feet)? And I would not use the clamps that come with it - get real hose clamps.
https://www.amazon.com/AloneGoer-95001-35003-60M-T...&psc=1
_________________
Lon

1969 Karmann Ghia convertible
1971 Westfalia camper

[David Bunin]

Thank you. My order has been placed. The link you gave was for a six-foot section, but they also sell ten-foot lengths, so I bought two of those and we'll see if that does the trick. I'll get real hose clamps.