ok guys, I need to replace my vent lines as my small leak has turned into a bad leak when I completely fill the tank.

The tank connecting lines are 12mm and the line running to the overflow on the fill tube is 14mm.

Bavauto can get the fuel line, but they're special order and expensive. Anyone know where to buy large diameter fuel line by the foot?

The largest I've found is 5/16", I need at least 7/16 and 9/16".

Do you guys think heater hose will hold up? That's the only big stuff I can find.

i went to carquest and they had them... they are in standard measurments though. take a piece of each or show it to them while it is on your car. i got mine for a whole buck and a half for a foot. try it out

There is a very well written write up with how many feet of what hoses to use and I did my hoses in about 3 hours or so. the big hose they didn't have in fuel line grade and no where I went in town had it so I just used heater hose. it'll probably only last another 20 years or so before it has to be done again....

here is the write up link

http://www.e21bmw.net/tech/breather/index.php

try jegs or summit racing stainless steel braided flex

Then I'll spend more than I need to and the braided stainless will rub the crap out of everything it touches.

Just need 1/2" fuel hose.

I got mine from the dealer. The big hose is expensive for what it is, though. Heater hose is not fuel/oil resistant, and will deteriorate quickly, as I found out when I used it for an oil return hose from my turbo. It lasted about 6 months under constant contact. The vent hose would last longer no doubt, but at best it would be a temporary fix.
--Dennis

Don't forget the original breather hoses were not fuel grade either and they only lasted 27 years on my 79....

While not the best thing I bet if that one hose was not fuel grade it wouldn't make a huge difference. All my lines but the big one are fuel grade on my 79.

I got it at the local Auto Parts Store in stock. Also check the local VW dealer. Same as the fuel pump inlet diameter.