Super Project '71: Part 16
Fuel and Fresh Air Vent Systems
From the March, 2009 issue of VW Trends
All contributors: Ryan Lee Price
Without the cargo liners (both...
Without the cargo liners (both top and bottom pieces) the completed trunk with the hoses and tubes should look something similar to this. Obviously the tank is in the foreground and the fresh air fan housing is at the top; however, there are a dozen or so parts that end up hidden and head in a variety of directions.
Basically, there are no two ways about this: You can't install the fresh air fan and vent ducting system without installing the fuel tank and the evaporative emissions control system at the same time. There are a couple of steps that dovetail between the two installations and it all takes place in the close confines of the trunk. In addition to that, make sure all of your knobs are in place and that you've installed the dash-mounted ashtray. After the fact, it is nearly impossible. Not surprisingly, there isn't a wealth of information regarding the evaporative emission control system on the 1970 and later Beetles, except for the general explanation in the Bentley book and a short how-to about fixing a fuel leak at www.superbeetlesonly.com. Other than that, you're really on your own, and hopefully you took a bunch of before pictures when you tore your Super down to a shell. You didn't? Oh, well, don't worry because we did.
In short, the emission control system consists of an expansion chamber that is connected to the tank that collects overflow gas from a full fuel tank. It is stored in this tube under the cowl until the fuel level eventually drops. In addition, the evaporated fuel from the tank (after the engine has been shut down) is forced up through the expansion chamber and into the ventilation lines. Then those fumes travel to the rear of the car where it is "washed" in an activated charcoal canister. The charcoal absorbs the vapors and, when the engine is restarted, the cooling fan blows the trapped vapors into the carburetor where the engine burns them off.
Sure, it sounds simple, but the complication of tubes, hoses and connections can challenge the patience of any builder. Because of this, we built and rebuilt the systems a number of times because there is a certain order of assembly. In addition to this, we realized that a lot of the parts needed aren't currently being produced, which makes for a difficult installation if your car is missing something.
A note about safety: We've said it before and we'll say it again, there's nothing more final than fire. Old gas tanks, even if they seem empty, still contain vapors, and vapors plus an errant spark or a buildup of static electricity can cause a large explosion in a flash. To combat this, always disconnect your battery and ground your car. Keep a fire extinguisher handy, however.
On the other hand, there's nothing remotely hazardous about the fresh air/heating ventilation system and you shouldn't worry about anything besides making aftermarket parts fit with OEM parts on original parts. Oh, but that's part of the fun, right?
Starting on the inside of...
Starting on the inside of the car, snap the center vent (113-255-483) under the dash pad and onto the body. The dash pad might need a little alternation (use a clean blade) so the vent fits snugly on the pad. There are a few clips on the vent that snap under the dash.
Underneath the cowling in...
Underneath the cowling in that same location goes the center defroster vent housing, which they don't make anymore so we hope you kept your old one. This piece snaps into the center vent and holds both pieces together.
These are examples of the...
These are examples of the hoses needed to connect the defroster vent to the defroster hoses in the quarter panel channels. On the right is the original plastic, ribbed hose, while the left hose is the one-inch paper aftermarket replacement piece. Though the plastic hose is better, as it needs to fit underneath the glovebox, the paper one is more forgiving in tight places and sharp corners.
The center vent hoses slide...
The center vent hoses slide onto the center connection of the defroster hoses and wraps underneath the hood springs and glove box.
This is the original fresh...
This is the original fresh air vent that directs air from the fan box into the cabin of the car. This is another part that isn't currently reproduced so if your pieces aren't in good condition, you'll have to find replacements. All ours needed was a little cleaning and they were good to go.
Once in, the perforated tube...
Once in, the perforated tube heads to the fresh air fan while the other outlet is directed down to the defroster hoses in the quarter panel channels. On the dash board are the corner defroster vents (113-819-635A) which snaps into place similar to the center vent.
Because our original vents...
Because our original vents that fit into the face of the padded dash crumbled to dust when we removed them, we needed to find a donor dash to take them from. Luckily this dash came from a cut up '71 Standard Beetle. A utility blade helped cut the tabs (see arrow) out of the padded dash.
We marked the position of...
We marked the position of the vent's mounting tabs (note the correct direction and location) and drilled two small holes into the pad. With some plastic glue we were able to feed the tabs into the holes and secure the vent to the dash.
At this time it is a good...
At this time it is a good idea to install the steel ventilation line up under the cowl where it is held down by three tabs on the body.
We fed the fresh air control...
We fed the fresh air control knobs through the dash pad and secured the mechanism with these two screws. The control wires should criss-cross over each other twice so they don't bind during operation.
These corrugated plastic pipes,...
These corrugated plastic pipes, officially known as fresh air box hoses (113-819-717B), connect the corner vent housings with the fresh air fan. They're flexible enough to bend during the installation of the fresh air fan box. Around these go a band insulation to keep the air routed.
The fresh air fan box slips...
The fresh air fan box slips under the cowl and is secured via three screws and washers. To create an air-tight suction that won't draw in air from the trunk, this hood seal (113-819-519C) fits neatly into the channel.
Their are two types of drain...
Their are two types of drain hoses for fresh air fans. This one, 113-819-533, fit Super Beetles, while the other two-piece units fit Standard Beetles
With all of the vent hoses...
With all of the vent hoses attached, each side looks something similar to this. Although we haven't plumbed each hose where it needs to run, we do have them hooked up correctly. The left hose (1) runs to the side vent, the center hose (2) runs to the center vent and the right hose (3) goes up into the A-pillar.
Once the vent system is mostly...
Once the vent system is mostly completed, we can begin work on the fuel tank. First start by attaching approximately 12 inches of fuel hose onto the tank's outlet tube with an appropriately sized hose clamp.
Unfortunately, with aftermarket...
Unfortunately, with aftermarket parts, there is always some adjustment needed and the fuel tank is no different. Though all of the tubes and attachment points are correct and in place, the mounting holes are invariably covered by a too-wide tank lip. Grinding away some of the outside lip of the tank exposes the mounting holes, but make note where the two tank pieces come together so you don't cut into the tank itself. Don't forget the foam rubber tank-to-body seal (111-201-621C).
Underneath the tank, the 12...
Underneath the tank, the 12 inches of fuel line is fed onto the hard line in the front frame horn. Shown here is the connection to the hard line at the engine end. This is where we will install our fuel filter.
Back up front, we fed the...
Back up front, we fed the filler neck into the tank and gasketed it with a filler neck seal (111-809-599A) and then this filler neck hose (311-201-219A). Two large clamps hold it tightly in place.
Once the filler neck is secured...
Once the filler neck is secured onto the tank it needs this rubber gasket around it to keep the filler neck from vibrating on the body.
Finally, the fuel sending...
Finally, the fuel sending unit is fed into the tank. The unit can only attach into the tank one direction, and it tightly cinches down over a rubber ring gasket.
Let the connection of the...
Let the connection of the hoses begin with these fuel lines that run from the filler neck back into the top corner of the tank. Within this line is a t-connector (see arrow) that allows fuel vapors to enter the expansion chamber. Appropriately sized hose clamps are used throughout.
The plastic expansion chamber...
The plastic expansion chamber sits under the cowl in this area. Though there's no particular place to bolt it down, it should fit snugly on top of the windshield wiper motor so it doesn't interfere with its movement.
On the passenger side of the...
On the passenger side of the expansion chamber (closest to the filler neck) is connected a length of 3/16-inch (inside diameter) clear plastic tubing and a 16-inch piece of fuel line.
On the other side of the expansion...
On the other side of the expansion chamber (driver's side) is connected two 12-inch pieces of fuel lines. Those two lines attach to the fuel tank and serve as a conduit to re-circulate overflow fuel back into the tank.
Cut into the fuel line leaving...
Cut into the fuel line leaving the passenger side of the expansion chamber is a t-fitting and another 12-inch piece of fuel line that connects to the t-fitting in the fuel filler neck line. Confused yet?
The plastic tube from the...
The plastic tube from the expansion chamber joins the steel ventilation tube located under the cowling.
On the other side of the ventilation...
On the other side of the ventilation tube is connected another length of plastic tubing that feeds down the same channel next to the fuel tank that the hard lines for the brake reservoir feeds through.
Down underneath the car on...
Down underneath the car on the "firewall" is a cross piece of steel ventilation line that inexplicably returns the passenger side of the car. The plastic line connects here.
The firewall steel ventilation...
The firewall steel ventilation line is connected via fuel hose to another steel ventilation line that runs the length of the pan. Missing are the hose clamps that we will add later.
The long line attaches to...
The long line attaches to the car via mount flanges that connect underneath three to four body bolts.
Underneath the rear passenger...
Underneath the rear passenger fender is yet another piece of steel ventilation line that connects to the long line in a similar manner to the front "firewall" piece. This line is held in place by the fender bolts, and then connects to the bottom of the charcoal canister with a foot-long fuel hose.
The thick hoses from the canister...
The thick hoses from the canister are fed into the engine compartment. The top hose connects to the fan shroud while the bottom hose wraps around the back of the fan shroud (some feed it through the deck lid spring) and connects to the air cleaner on top of the carburetor.
Back to the front of the car,...
Back to the front of the car, we did some minor adjustments to the two-piece trunk liner, namely we were forced to cut clearance space for the fresh air fan box. Once installed we considered the job done.
Conclusion:Some of the details needs to be addressed. For example, we didn't connect the trunk release or the fuel door release levers. As well, we'll need to re-install the correct fan shroud with the flange to accept the charcoal canister hose, and later we'll add to the system the water canister and lines for the winshield wipers, and consider replacing the jack.
If you smell fuel inside the cabin or inside the trunk, you've got a leak somewhere. Either you haven't used brand new fuel lines or you've got a component that no longer holds its integrity. Sometimes, the expansion tube and charcoal canister (which are no longer offered) don't work and must be accounted for. If that's your problem, you must reroute some lines to block of these two things. Avoid any leaks at all costs. In reality, a 1971 Super doesn't have to pass smog tests, and because of that, it doesn't have to be environmentally sound. Converting your tank from this complication of tubes and hoses to that of an earlier system is simple: Merely connect a hose from the filler neck to the top left corner of the tank and connect together the two inlets on the upper right side of the tank, therefore bypassing the charcoal canister system and lines and the expansion chamber. For more information on this change, check out www.superbeetlesonly.com.
Next month, we're going to take you through the installation of the hoods and fenders, the chrome trim, bumpers, brackets, turn signals and lights, essentially, everything on the outside of the car. Until then, stay Super.
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