tank venting

donn Wolfsburg Elder

3,515 posts · joined Nov 2005 · 24 Jun 2012, 10:40 am

#909732

Google is not my friend, so much highly technical info that I have gone into information overload, (not hard for me 🤪)
So here's the question, hoping for a simple answer, keeping in mind that the fuel tank is not a standard Dub tank and it's in the wench.
I have vented the tank from up high in the side of the tank via a tube to the filler neck near the cap, this gives a way for the air to escape from the tank while filling (the filler neck is almost level with the top of the tank and enters the tank via a steel tube about the size of a standard VW filler tube running almost horizontal into the tank) the filler cap is not vented, so when it is installed there is no way for air to enter the tank (esential I would think 🤪) I was thinking that if I drill a small hole, maybe 1-1.5mm, in the filler cap that will overcome the problem, as the cap is not inside the car, it's right at the back exposed to the elements, then I shouldn't get any fuel smell to bother me, but I'm not sure about the merit of what I am intending to do,
What do the gurus think?
Thanks
Don

I dream of a day when a chicken can cross a road without being asked for it's motive!

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 · 24 Jun 2012, 10:54 am

#909735

donn wrote:Google is not my friend, so much highly technical info that I have gone into information overload, (not hard for me 🤪)
So here's the question, hoping for a simple answer, keeping in mind that the fuel tank is not a standard Dub tank and it's in the wench.
I have vented the tank from up high in the side of the tank via a tube to the filler neck near the cap, this gives a way for the air to escape from the tank while filling (the filler neck is almost level with the top of the tank and enters the tank via a steel tube about the size of a standard VW filler tube running almost horizontal into the tank) the filler cap is not vented, so when it is installed there is no way for air to enter the tank (esential I would think 🤪) I was thinking that if I drill a small hole, maybe 1-1.5mm, in the filler cap that will overcome the problem, as the cap is not inside the car, it's right at the back exposed to the elements, then I shouldn't get any fuel smell to bother me, but I'm not sure about the merit of what I am intending to do,
What do the gurus think?
Thanks
Don

Hi Donn
I don't use google....
Yes a hole about 2mm would work
My 68 beetle has a hose [about 2.5-3mm ] goes over the top of the dash and down to a metal pipe where it goes outside next to the spare tyre.

as You probably know lawn mowers have vented caps and actually many cars - early VWs all had vented caps...
a lot of car fuel caps actually vented on the side or underneath where it couldn't be seen..

a hose or pipe off the filler neck or vent pipe may be better so that rain can't get sucked it.

LEE

- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

waveman1500 Also rides a Honda

1,346 posts · joined Dec 2009 · 24 Jun 2012, 5:24 pm

#909781

Don't drill a hole in the cap, fuel will slosh out of it as you go around corners when the tank is full. The best way is to put a T-piece into your existing vent line. Then run a hose from that, loop it up high to stop liquid fuel from escaping, then run it back down and outside to a suitable venting point.

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68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 · 24 Jun 2012, 5:46 pm

#909789

When You look at Donn's car, there isn't really anywhere it can go UP wards??

but a tee piece [windscreen washer t piece ] on Your vent hose and going up over the top of the rear of the dash should be enough elevation and then down near the brake master cylinder etc...
I suppose then a small lawn mower type of fuel filter could be plugged on to stop any dust getting sucked up..?

if a windscreen washer t piece isn't the easy to use size check out bunnings in the gardening hose fittings section
[if they have them..lol] or a plumbing hardware shop...

late beetles did have a long plastic double tube with 4 hose ends from memory... where they all went I'm not sure...
weird looking thing actually....

cheers

LEE

- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

cam070 Custom Title Time!

1,332 posts · joined Jul 2009 · 24 Jun 2012, 9:15 pm

#909856

Please be careful what you use, and use a plastic part that can deal with fuel vapour. Some of the plumbing/gardening parts I am sure will do the part in the short term, but will no doubt be corroded away in the medium to longer term.

donn Wolfsburg Elder

3,515 posts · joined Nov 2005 · 24 Jun 2012, 9:24 pm

#909862

cam, I've been using brass air hose fittings, Lee, thanks for the info but as the tank is at the rear of the car it would be really something to get a line up over the rear of the dash (not that it realy has a dash 😁), still worth thinking about the line to vent as waveman also suggested.
Thanks

I dream of a day when a chicken can cross a road without being asked for it's motive!

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 24 Jun 2012, 9:32 pm

#909865

waveman1500 wrote:Don't drill a hole in the cap, fuel will slosh out of it as you go around corners when the tank is full. The best way is to put a T-piece into your existing vent line. Then run a hose from that, loop it up high to stop liquid fuel from escaping, then run it back down and outside to a suitable venting point.

x2

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