[T3] 71 Squareback MT/FI - Mystery Hose / Canister

Jim Adney jadney at vwtype3.org
Sun Feb 18 11:31:23 PST 2018

All those parts are part of the vapor recovery system begun in '70. Those 
parts stopped being effective decades ago. That system consists of the 
following items:

Hoses and steel lines above the gas tank that carry overflow gas and fumes 
to an overflow tank under the LF fender.

Hoses and lines that run from the overflow tank to a charcoal cannister 
above the transmission (to the left of the engine on '70s.)

Hose that carrys slightly pressurized air from the L fresh air elbow to the 
charcoal cannister.

Hose that allows air and gas fumes to be sucked into the air cleaner on the 
R side.

On 17 Feb 2018 at 15:29, Wisconsin Spryers wrote:

> My questions are:
> 1) What is the purpose of this canister?

The cannister is filled with activated charcoal to absorb gas fumes.

> 2) Is the routing of the hoses correct?


> 3) Is there any maintenance required on this canister?

The cannister is supposed to be replaced periodically, but that's pointless 
now. Here's why:

All the steel lines have long since rusted inside, blocking them completely, 
so that fumes are no longer able to get from the gas tank to the cannister. 
It's also likely that your overflow tank bracket has rusted away and the tank 
is gone. Mike is correct, that this tank collects dirt and promotes rust in this 

The best thing to do is to remove the overflow tank, charcoal cannister, all 
the lines and hoses, and plug the openings in the fresh air elbow and air 
cleaner. The overflow kit that I sell includes parts to convert the vent system 
back to the earlier version that vents to the outside. That's the only practical 

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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