Venting, should it be done?

[Nick_J]

After reading a few threads recently, I experimented with venting last night.
Brimmed it to begin with, then vented, then brimmed then vented, then just topped up, but there was room for more fuel. This brought me to 43.5 litres.

I was wondering, if our cars have this venting device on them, then surely thats not their for our use really, there must be a purpose for it. If there isnt, then why not just make the tank without the venting thing on it?

I read it was to do with deisel expanding, but if this would cause such a problem, then why put a venting valve there for us to exploit?!

Any comments would be good

 

[MagicFR]

the venting valve to my understanding is there to help keep some air in the tank so that in hot climates when fuel expands it doesn't blow up the tank

in UK weather and especially at this time of the year I SERIOUSLY doubt it sthing like that will happen.

 

[BJM]

I doubt it would "Blow Up" the tank. What would happen is the diesel would expand and then find a way out of the tank (through the 'Drip catcher' in the filler cap for example. When filling up and venting I always make ure I'm going to br driving 20 miles straght away. I usually manage around 50litres in the tank from empty.

As said above, unless seriosly filling the tank rihght to the top then not using any of it, I doubt the British weather would heat up enough to make the diesel expand significantly.

 

[Leigh15]

The vent isn't there for you to use. When you screw the filler cap back in it activates the vent to make sure the fuel drops down in the tank

 

[Nick_J]

ok then cheers guys

 

[Boom^]

Ive vented a lot and never had a problem, just means i dont have to stop to fill up as often. Particularly good on long 500 mile drives

If venting could cause fuel tanks to explode and stuff then i guess they wouldnt have made the catch easy each enough to push in with the filler hose.

 

[Leigh15]

I used to use it regularly too and never had an issue - though I expect it would be a different story in the blazing heat in southern Spain!!

 

[sssstew]

yes, redtornado from the US have said even in some US heat it doesnt expand enough to come out of the tank.

jones - the way i vent it to just push the vent button in with the end of the fuel nozzle as your filling slowly it expels the air and fills up at the same time.

 

[MattBennett]

I vent my tank every time I fill up. 36k miles now and never a problem but I do do about 20 miles or so before I stop the car.

 

[rashcupra]

what do you exactly do diffrent with venting to normal filling up what is the diffrence as im new to this style of refueling??????

 

[MattBennett]

There is a small lever on the right hand side of the filler neck as you look at the car. When the pump clicks off I depress this with the filler. You can hear the air in the tank escaping and can get more fuel in the tank. Never thought about venting while im filling. Will do this next time to save time. Some people do look at you a bit funny when you have been stood there for a wee while filling your car

 

[rashcupra]

my fuel filler looks like a hole with a cap and a flap inside it but no lever

 

[mattyfab]

The only problem I find with venting whilst filling, is that some diesel tends to splash out all over you!!!!!

But its a good thing to do, saves you going to the petrol station so much!!

 

[Georgel]

I still can't see this button. :?

 

[DIFT]

my fuel filler looks like a hole with a cap and a flap inside it but no lever

Go back to the petrol boys Rash...

This is diesel only

 

[BJM]

My petrol FR had the valve for venting!

 

[mattyfab]

The thing looks like a little bolt head inside the filler cap. Its about in inch in and on the right hand side (as you look at the filler).
Push it in (towards the inside of the car) with the filler nozzle. It goes back 1 or 2 CM's. You should hear a gush of air if you have done it right

 

[mattyfab]

Does petrol expand in the way diesel does???

 

[luckymjr]

PETROL expands at a much lower temp than diesel

Here's a quote from a diesel forum on fuel expansion :

All fuels expand at the right temp , and depending on what fuel it is depends on the temp it will start to expand before turning into gas (or vapours) and this is know as it's flash point. Flashpoint is summed up like this:
The lowest temperature that a fuel gives off sufficient vapour to cause a fire or explosion when intorduced to a flame or spark. (Or words to that effect)
From memory, i think Petrol is around 21 degrees C (or in that region) and Diesel is about 54C (again, in that region) so to fill up a petrol tank using the expansion area wouldn't be a good idea when the weather is warm enough to reach 18 degrees or above, whereas a diesel car would get away with it most of the year (in the UK) as it very rarely gets above 35C, so the diesel won't expand in the tank.
I have ALWAYS filled mine to maximum at every fill all year round and never had a problem, just less visits to pump.

Mark

 

[mattyfab]

Cool, cheers 4 that