Collapsing fuel tank

Itsjustmetal

Active member
Joined
Nov 19, 2012
Location
Seattle
TDI
2010 JSW TDI
Just found this today. Any ideas as to why this could be happening? I'm guessing only solution is to replace the tank. Makes sense as to why I am having so many problems with filling the tank and why I have a smaller capacity.

 

elitegunslinger

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Apr 26, 2010
Location
Barnegat NJ
TDI
2010 Golf TDI :D
It's been very cold and the plastic tank is contracting with the ambient temperature? Kind of like a water bottle that has been at room temperature then sealed, then thrown outside in the freezing cold. That bottle shriveling effect. That is my vote.
 
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Ski in NC

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Jul 7, 2008
Location
Wilmington, NC USA
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2001 Jetta ALH 5sp stock
Maybe wrong gas cap? Gasser cars have sealed caps, diesels are vented. I think.

Try running with tank cap cracked loose.
 

El Dobro

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NJ
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Do you hear any noise when opening the gas cap?
 

Itsjustmetal

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Nov 19, 2012
Location
Seattle
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2010 JSW TDI
Weather has Been low 40's high 30's lately so should be no ice. Yes I do hear pressure released when you loosen the fuel cap. Wasn't sure if that was normal or not. Looks like ill be dropping the tank to check the lines. Any way to get the tank back to normal after unclogging the line if that happens to be the culprit?
 

El Dobro

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NJ
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2017 Bolt EV, 2015 Spark EV
Weather has Been low 40's high 30's lately so should be no ice. Yes I do hear pressure released when you loosen the fuel cap. Wasn't sure if that was normal or not. Looks like ill be dropping the tank to check the lines. Any way to get the tank back to normal after unclogging the line if that happens to be the culprit?
Maybe it's vacuum and not pressure you're hearing.
 

Ol'Rattler

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Joined
Jul 3, 2007
Location
PNA
TDI
2006 BRM Jetta
Clogged tank vent is my vote.
The TDI's have no EVAP system like gassers and are vented to atmosphere by a vent separate from the cap.

If you hear a whoosh when you remove the cap then the tank is not venting properly and a vacuum is being created in the tank collapsing it and making filling difficult.
 
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El Dobro

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Feb 21, 2006
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NJ
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2017 Bolt EV, 2015 Spark EV
Does your fuel cap have "diesel" or "D" written on it? If not, could be the wrong cap. If it does, the vent may be jammed.
 

El Dobro

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Location
NJ
TDI
2017 Bolt EV, 2015 Spark EV
Let's see, maybe either the vent in the cap is bad or the filler neck. As for the tank, instead of replacing it, try removing the pump and see if you can push the tank bottom back out.
 

TNriverjet

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Oct 18, 2011
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Mid TN
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2013 JSW TDI 6MT
Let's see, maybe either the vent in the cap is bad or the filler neck. As for the tank, instead of replacing it, try removing the pump and see if you can push the tank bottom back out.
I would think the weight of the fuel in the tank would "push" it back out if you could sort out the venting issue.
 

schultp

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Joined
Mar 11, 2008
Location
Michigan
TDI
2010 Jetta Sportwagen, 6sp manual
Or, perhaps fill with fuel and then use one of those suction handles that is used to pull out mild sheet metal dents. Attach to the bottom and pull the bottom of the tank down.
 

Itsjustmetal

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Nov 19, 2012
Location
Seattle
TDI
2010 JSW TDI
That is a great idea right there! I think a little heat may be in need too. Might see if I can drop the tank this weekend and check the vent tube and also ill order a new fuel cap just to eliminate that as a factor.
 

Itsjustmetal

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Nov 19, 2012
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Seattle
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2010 JSW TDI
Any tricks to pulling the intake fuel pump? Just want to be safe as I know these are high pressure systems
 

Scoutx

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Jun 4, 2012
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Virginia
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2012 Jetta (6MT) - 1000 Mile Club (retired)___ 2015 Jetta SEL (6MT)
I would think the weight of the fuel in the tank would "push" it back out if you could sort out the venting issue.
I would agree. The fuel weighs a bit and after time the tank will relax under the weight and "deform" back to orginal shape. Particularly once we get back into summer temps.

In any case, I would have it on file with the dealer so that if it doesn't it's covered as a warranty issue.
 

motorhead2

Well-known member
Joined
Oct 21, 2012
Location
California
TDI
2012 Jetta TDI Sportwagen
A long time friend sucked two tanks on his 1979 rabbit. We found after the second tank shriveled that the fuel tank vent valve had stuck and the primary fuel pump slowly sucked it to about half capacity.
 

53 willys

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Aug 2, 2008
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Utah
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2010 Sportwagen TDI~LOVE/HATE~


Take it this is not supposed to be like this?
I dont know if that is supposed to be that way....but I'm certain that if it's not, there should be a hose near by that would plug into the vent.....I have never seen a vent that does not have a hose attached to it.
 

Itsjustmetal

Active member
Joined
Nov 19, 2012
Location
Seattle
TDI
2010 JSW TDI
Apparently volkswagen didn't take off the cap at some point. As there is a tsb about if a customer complains about not showing full tank after filling up, the Pull the cap. There was no other hoses around or on the tank. No other places to even allow it to vent back into the tank like the lower vent tube. I no long have any kind of hissing when intake the cap off. Tank seems to be holding its Newely reformed shape (what a pain that was, to get it back to semi normal). Going to drive it a few more days then its getting parked till it goes to the dealer on the 23rd. Egr issues and also having them Look over the dsg as my mechanic says its leaking, when it shouldn't be.
 

Itsjustmetal

Active member
Joined
Nov 19, 2012
Location
Seattle
TDI
2010 JSW TDI
I wish I would have planned better and gotten the 90 degree fittings and volkswagen cleaner and epoxy as I would have done the vent trick
To get more gas out of the tank.
 

shuswap

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Joined
Dec 12, 2010
Location
British Columbia
TDI
05 Golf TDI BEW auto
I'd be surprised if that tank didn't return to it's original shape after/during the summer months and keeping it near full.

It was formed in the original shape and stressed into a different shape. Once the stress is removed it should work it's way back into it's pre-stress shape.

Or maybe that's just wishful thinking?
 
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