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Finn mc Missile



Member Since: 08 Feb 2014
Location: Home
Posts: 17

Finland 2008 Freelander 2 TD4 SE Manual Tonga Green
Fuel cap - vacuum in tank

Hi,
Every time I fill the fuel tank, there is a quite strong vacuum in the tank.
Anyway, it hasn't caused any problems (yet?!), but I keep wondering is this normal?
There should be some kind of valve in the cap, letting air come in, right?

My last car was V70, same company product and this never happened.

Post #218992 9th Mar 2014 7:52 am
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alex_pescaru



Member Since: 12 Mar 2009
Location: RO
Posts: 4642

http://www.freel2.com/forum/post218203.html#218203

Post #218994 9th Mar 2014 7:57 am
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Steve D



Member Since: 19 Jan 2013
Location: Essexshire
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United Kingdom 

Great link. Thumbs Up (If you can speak more than one language). Laughing Past: FL2 TD4 HSE Auto
Evoque SD4 Dynamic Lux Auto
Present: Audi A3 S Line.

Post #218996 9th Mar 2014 8:39 am
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Gordy



Member Since: 01 Feb 2014
Location: Stirlingshire
Posts: 65

Scotland 2010 Freelander 2 TD4_e GS Manual Lago Grey

Glad there were pictures to support  
I'd say yes eventually there will be an issue, back in the old days mechanical pumps would fail due to inadequate stroke pressure v tank vacuum pressure. Electric pumps may endure this pressure a little longer however your breather valve in the cap can only get worse there for on a full tank drain the vacuum will increase greatly.
New cap or some delicate DIY Wink

Post #219004 9th Mar 2014 9:52 am
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ad210358



Member Since: 12 Oct 2008
Location: Here and There
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England 

Both the Freelanders I have had, there was a a vacuum when opening the cap, but never had a problem with it, it is how it is designed.

Post #219006 9th Mar 2014 9:57 am
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Gordy



Member Since: 01 Feb 2014
Location: Stirlingshire
Posts: 65

Scotland 2010 Freelander 2 TD4_e GS Manual Lago Grey

Alex had mentioned this also, depends on how much of a vacuum I suppose. There must be a balance to counter the tension in the spring and there for allow air to be drawn into the tank on demand, however if it's hissing like a swan then that would be worrying.......

Post #219008 9th Mar 2014 10:08 am
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Finn mc Missile



Member Since: 08 Feb 2014
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Posts: 17

Finland 2008 Freelander 2 TD4 SE Manual Tonga Green

Thanks Alex for the link, no habla but pictures were good Thumbs Up
Mine was really "hissing like a swan", we'll see how much this helped.
I opened fuel cap. It was surprisingly dirty, just like in those pictures.
Cleaning with cloth and air compressor.
Now that valve seems working quite ok, next time refuel shows that is there any difference.

Just wondering, because of that spring tensioned valve in the cap... when vacuum exeeds spring tension, it's short time like a vacuum cleaner.
Air flow must be quite high for a while and if it's dusty conditions, no wonder why it sucks all that that dirt in the cap Shocked
There should be a filter Rolling Eyes

Post #219082 10th Mar 2014 9:50 am
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Aveling



Member Since: 24 Mar 2011
Location: Cardiff
Posts: 265

United Kingdom 2014 Freelander 2 SD4 Metropolis LE Auto Firenze Red

Strange this - I asked the same question back in December when I changed my car from an 07 HSE to a 60 Plate HSE.
Opinion at the time being it was meant to do this - I somehow doubted this!!!
Now we seem to have a definitive answer.

Post #219107 10th Mar 2014 2:02 pm
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Finn mc Missile



Member Since: 08 Feb 2014
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Finland 2008 Freelander 2 TD4 SE Manual Tonga Green

Back to this once more.
Cap cleaning result was significant.
There still was vacuum in tank when I opened the cap, but maybe 1/3 compared before, or even less.
Nothing to mention, anyway Whistle

Post #219939 19th Mar 2014 3:23 pm
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PuffyMcScrote



Member Since: 10 Feb 2014
Location: Richmond, VA
Posts: 99

United States 2008 LR2 i6 HSE Auto Zermatt Silver

As a side-note, my last car (a Dodge Magnum) would throw engine codes and the dreaded CEL if I forgot to tighten the gas cap enough to allow for a vacuum.

Post #219942 19th Mar 2014 3:34 pm
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Chuckalicious



Member Since: 23 May 2014
Location: Midlothian
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Interesting thread. I have had a fairly significant hiss and suck when opening the cap since I got the car in June (it is a 60reg).

Took a look at the cap today and it is spotless, almost as if it has been replaced. Phoned local dealer and spoke to service manager. He has never heard of an issue with the caps or of a vacuum in the tank. However he would have to book it in with a risk of £150 charge if no fault found.

Seems to be disagreement on whether or not there should be any hiss or vacuum....

Post #237086 7th Oct 2014 12:22 pm
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pab



Member Since: 28 Aug 2012
Location: Now in Mid-Wales
Posts: 2006

United Kingdom 2009 Freelander 2 TD4 XS Manual Lago Grey

Aveling wrote:
Strange this - I asked the same question back in December when I changed my car from an 07 HSE to a 60 Plate HSE.
Opinion at the time being it was meant to do this

Maybe you should have read the replies posted at the time! Quoting from my own response back in December:

Quote:
Something wrong there, Aveling. A blocked breather can cause other problems too, like fuel starvation and even failure of the fuel tank itself (although the latter was more of a problem with steel tanks). It also makes the fuel pump work harder as it's fighting against the negative pressure in the tank.

I don't recall off-hand (can check later) but I think the breather mechanism may be in the cap itself, so you may need a new cap.


That's not quite 'meant to do it'! Rolling Eyes

Post #237105 7th Oct 2014 4:06 pm
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Chuckalicious



Member Since: 23 May 2014
Location: Midlothian
Posts: 1796

United Kingdom 

Thanks for the reply. I did read all the responses and unless I've missed the point, I'm not sure either way if it is meant to do this or not. Apologies if its obvious...

Post #237107 7th Oct 2014 4:13 pm
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realspeed



Member Since: 26 Mar 2011
Location: East Sussex
Posts: 574

United Kingdom 

Many years ago nowI had the same problem and got over it by drilling a small hole in the filler cap. Totally wrong I know but it did the trick Ex 2010 Freelander2 GS-e Diesel manual Silver owner

Post #237109 7th Oct 2014 4:28 pm
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pab



Member Since: 28 Aug 2012
Location: Now in Mid-Wales
Posts: 2006

United Kingdom 2009 Freelander 2 TD4 XS Manual Lago Grey

Chuckalicious wrote:
Thanks for the reply. I did read all the responses ...

Mine above was in repose to another post earlier in the thread, not yours.

A slight hiss on removing the cap is not unusual - there is a spring in the venting mechanism (in the cap) and venting will only occur when the pressure exceeds the force of the spring. (That said I never seem to get a hiss from mine.) But anything more than a slight hiss, and in particular anything which makes the cap hard to remove, suggests a fault in the venting mechanism and could lead to fuel starvation, etc.

Post #237112 7th Oct 2014 4:34 pm
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