venting/ventectomy questions

jkp1187

Veteran Member
Joined
May 8, 2008
Location
Pittsburgh, Pennsylvania
TDI
none yet
A couple of noob questions on the subject. (I did a search, couldn't find these answers).

A lot of people talk about doing a ventectomy on their TDIs, which I gather has to do with removing some sort of vent in the filler tube that will allow them to squeeze some more fuel into the tank.

But what purpose does the vent have in the first place? Is there any negative consequence to removing it?

Second, someone in another thread made an offhand remark that he was talking to someone "while venting" at a diesel station. What exactly does "venting" mean?


Thanks in advance!
 

Fahrfuwerfuelen

Veteran Member
Joined
Dec 7, 2004
Location
Puget Sound
TDI
Jetta, 2005 (A4), Platinum Gray
jkp:

This subject has been covered extensively. Anyway, a ventectomy is the removal of the little lever inside of the fuel intake. After you remove the cap, you should see a tab at about the 9 o'clock position. The vent was really designed to prevent overfilling of gas tanks as gasoline expands more than diesel. As the volume fills the tank, the vent shuts off at a predetermined point so you can't overfill. You can add more fuel, by pressing the tab forward ("Venting"). An alternative is to remove the tab and spring, so you won't have to mess with the tab ("ventectomy").
 

NorthernMage

Veteran Member
Joined
May 5, 2005
Location
Victoria, BC
TDI
2012 Jetta TDI, 6MT, Platinum Grey
JKP, you can "vent" by holding down that little black tab with the fuel nozzle which seems to be designed so that it is depressed by the fuel cap when it it tightened down. This allows you to completely fill the tank with another 1 - 2 gallons of fuel into the "dome" expansion space allowed for gas and gas vapours in the fuel tank - which is the same tank a gasser has. Since diesel doesn't expand or vaporize like gas you don't need to leave this space empty.

If you do a "ventectomy" you don't have to stand there holding down that slippery little tab with the fuel nozzle. You just listen for the "rush of air" to stop coming out of the vent hole behind the tab which indicates you have filled up the extra space with fuel, or at least foam!!! With the extra fuel in there it takes a very long time to come off of full and you get another hour or two of driving before you have to stop. That is how people are getting 700 miles tanks - and higher....
 
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