What have people used for a fuel tank breather and where can I buy one?

Cheers,

Pat...

cant you use a tyre valve?


[whisper]did you manage to order the DD2's[/whisper]

I heard that - but surely it has to let air in and out as you fill and use the fuel in the tank?

Pat...

I just used a bit of rubber tube, got it as high up as possible then down out of the bottom of the car.

No problems encountered so far

Cheers

Mark

don't you use 2 one to leak in and one to leak out

I've been told you don't need a breather on the tank, if you fit a cap that can breath.

I'm interested if this is true.

Yep, that's true - but the ali aero cappy things are non breathers.

Two bike/car valves - that's two hole in the tank isn't it?

Pat...

I used a vented cap, but surely a bit of hose with a restrictor in it such as a .6mm mig nozzle, would allow air in and out but not allow fuel to leak to rapidly in the event of an accident , or two bike valves connected to a tee piece as used in windscreen washers .
Paul.

Surely one car (Schreider?) valve to let air in would be OK - that's what's on my car now. You wouldn't need one to let air out as you're filling the tank as you'd have the cap off?!

Wyn

I drilled a tiny hole in the back of the filler cap pipe.
only 1mm.
No probs.
If its getting laid up for a while just put some tape over it to seal it.

Mate does fuel systems for a living.

when i talk about what we do his reaction is funny. It can basically be summed up as ......

Wave arms over head, look scared, repeat, "you're all going to die".

Now i realise he's being melodramatic but, he has to jump through hoops for a reason. How would you like to be upside down in a ditch with fuel pissing out of your tank onto you?

If you're about to say whats the chance of that i know of a number of people who've been in cars that have rolled!

I had a think about what i could make or make do with,in the end i thought best to be on the safe side and bought a one way breather valve from thinkauto.

http://www.thinkauto.com

http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=right_in_the_boot.jpg

[Edited on 10/12/05 by bob]

This is nothing to do with the car rolling over - that is something else.

This is to with not creating a vacuum in the tank so it doesn't collapse.

So basically, from the tube from the tank, I could fit a car valve upside down in the end of the tube? This would suck air in when the fuel goes down would it not?

Pat...

Don't forget the other function of the breather, to allow pressure build up due to expansion to be released.

Mick

Bob - what size pipe does it push on and has yours got a pipe coming off the side of it?

Pat...

Maybe remotely relevent but not sure...

My dads Hyundai seems to work with a vaccume in the tank, when you fill it up after a drive you can actually hear it suck quite alot of air in as you unscrew the cap.

Maybe they can do this with injection, or it has another way of allowing air in if and when it needs it. (I suppose if you pressurise the tank it might act as a buffer to lessen how often the pump runs)
Might be worth looking at how manufactures prevent vaccumes in their systems, either at the scrapyard or in the Haynes.

Pat

Mine is a regular piece of fuel pipe (8mm i think)

I just drilled and tapped a 1/4bsp brass fitting into the tank then fitted the small piece of fuel pipe and then the valve.

quote:

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Originally posted by Avoneer
This is nothing to do with the car rolling over - that is something else.

This is to with not creating a vacuum in the tank so it doesn't collapse.

Pat...

---

Sorry mate, thought you were just on about the ones that are for roll over protection only.

Guess I'll order a posh "think" one - can't go wrong then.

Pat...

The breather that some cars have has no valve in it. It consists of a length of hose that goes from the top of the tank (where it connects to the tank) down to the bottom of the tank and under it then back up to the top where it's open, sort of in a big 'U'. It has to be designed so that no matter which way up the tank and breather are, the fuel can't run out of the breather.

[Edited on 10/12/05 by Kowalski]

again this is where my mate chimes in ....... and what are you using to create this big u? Rubber? Pah, lasts about 3 seconds in a fire....... then fuel will wee all over you.

(he's given me this lecture more than once)

p.s. sorry i was a little condensending in my last post - was rushing to get out.

I have a pipe that runs from the top of the fuel tank to the air filters.

Any good?

Production cars seem to vent all sorts into the airbox.

Paul G

quote:

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Originally posted by MikeR
again this is where my mate chimes in ....... and what are you using to create this big u? Rubber? Pah, lasts about 3 seconds in a fire....... then fuel will wee all over you.

(he's given me this lecture more than once)

p.s. sorry i was a little condensending in my last post - was rushing to get out.

---

most cars now use plastic covered aliuminium with reinforced, plastic fireproof overbraid flexi connectors.

I've got 5 lines from the BMW mini in my garage - ex display and heading for the skip!

(edited to add, my mates company does plastic covered Ali, no idea what other suppliers use. Was going to mention companies he works with but don't want to get him in trouble in case i accidentally give away trade secrets)

[Edited on 11/12/05 by MikeR]

Hi

I used a one way breather valve from https://www.harris-performance.com/website/frameset2.htm

Adrian
Rescued attachment breather

they look just the job. If you want to spend more money i'm think Demon do one that will screw into the top of your tank so no need to have rubber hanging around.

The Harris Performance ones look really pretty but they are only a simple one way valve. This will allow air in (to stop tank implosion) but prevent expansion pressure escaping. So on a hot day, when your tank is roasting, won't there be a risk of vapour pressure leaking through a weak pipe union or similar..... or am I just paranoid?

The ThinkAuto ones are a little more sophisticated (and more expensive at £25 each!)

Quote" A range of fuel tank valves that allows 1)air in to replace fuel used, 2) air out due to heat expansion. 3) a positive shut off to prevent fuel escape, due to splashing or even roll over. This is achieved by a two ball system, one hollow plastic, one solid steel."

I'm looking into these soon as I have twin tanks to worry about. The TRL7 (not shown) is for in line fitting into ¼” bore hose and must be mounted vertically.
Probably the dogs danglies but at a cost!




[Edited on 11-12-05 by RazMan]

for filling up it isn't necessary because you have the cap taken of the tank..

sow whats the point??

its only for vacuum... well i have an loackable filler/aero cap..and i'm sure its leaking...enough sow no breather fitted...

Tks

Here's more bedtime reading from the Newton Products site - I think they manufacture the valves.
linky

I managed to get mine with a little discount from thinkauto,i just mentioned this site and locostcar club.

I'm pretty sure is was about £22 or less,i did pick up though.

The harris ones do seem a keen price though.

quote:

---

Originally posted by MikeR

quote:

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Originally posted by Avoneer
This is nothing to do with the car rolling over - that is something else.

This is to with not creating a vacuum in the tank so it doesn't collapse.

Pat...

---

No Pat, this is everything to do with being in an accident. You need a vent in your tank to stop the vacum. What i'm saying is make sure your vent is safe. Think not just for stopping the vacum but when you're in an accident. Those with lines that run up to the roll bar and back down are not safe! What i'm doing is fitting a vent from stoneleigh. Its not perfect as its going to be attached via a small rubber tube which should (hopefully) be fireproof.

I find it strange but the rules on building road cars are now more strict than race cars in many areas. This is one of them.

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PS.............to those using "PROPER" vent valves.......................................put some fuel in the tank and turn it upside down...............................I got a shock when I saw the fuel pouring out of the - fairly expensive - vent valve............hence the looped kunifer pipe on the grasser!

[Edited on 11/12/05 by NS Dev]

quote:

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Originally posted by NS Dev


Mike, I just use (on the grasser) a piece of copper brake line, from the very top of the tank, looped around the tank and down to below the bottom of the tank, near ground level.

Car right way up, fuel can't get out, car upside down.......fuel can't get out...........car on side.......fuel can't get out.

Simple, with the pipe looped around the tank, whichever way up the car lands, the fuel has to flow uphill, so it won't leak out.

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Aaah, but, what if you're rolling down a REALLY long hill, every time the car does a complete revolution a small amount of fuel will leak out :p

(ok ok, good solution! i'd also squash the end of the tube so only a limited hole existed cause i'm like that).

but in fact you make then an connection to your tank...

and then the problem arises that you car needs to smell to petrol, because out of that tiny hole is comeing tank vapoour...

i thought the normal car industie had some filters for it?

i think the best thing we can do is build an spring powered undo vavle..

should be easy! sow locost guys come up with something thats shutdown when you don't use the car!

Tks

Something like this,

when the sucking force wins from the spring it untapers the little hole sow it will suck air in, then the spring will win and it will be closed again..

in an uppside down case, the weight will close the valve anyway...
Rescued attachment Tankventevalveidea.JPG

if we're being acurate

All flaps / holes in the fuel tank should have a spring mechanism on them so if the tank is upside down the flap stops the fuel rushing out.

something else "you're all going to die" mate couldn't believe we didn't have to have!

quote:

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Originally posted by MikeR
Aaah, but, what if you're rolling down a REALLY long hill, every time the car does a complete revolution a small amount of fuel will leak out :p

(ok ok, good solution! i'd also squash the end of the tube so only a limited hole existed cause i'm like that).

---

quote:

---

Originally posted by MikeR
Mate does fuel systems for a living.

---

Stop playing at making cars would probably be high on the list, followed by keeping that death trap away from him.

The problem is, he has to go through more regulations than you'd believe. Each there for a good reason. We don't.

Basically, get a strong tank. Put flaps on all openings so fuel can't flow out if the car is upside down/ on its side. Remove all rubber from the system & use something fireproof. Sacrifice a chicken and pray to your favourite deity.

He was explaining what once company had had to do for Rolls Royce. Because of emissions rules, you can only emit so many hydrocarbons a day. With the rollers having such big rubber tyres they give off "loads" (relative term) of hydrocarbons. The fuel system therefore had to be near zero emissions to save the environment.

[cough] mpg on a roller? [cough]

tks, surely the pair of bike valves would be just like the sprung devices you drew? These probably wouldnt leak when immersed, but a small bit of pressure either way would open one or the other. You need one to let air out, because the air in your tank will expand significantly on a hot day, especially in a garage, maybe bending the tank.

Hello,

I'am using some from a shipyard, they are waterproof and from alu.

They where only 4,50 euro. with antiroll membraam.

Greeting Daniel

Sorry for being a bit behind but I got mine from here!!!!!!!!!!!

Carl