On Jul 11, 2008, at 6:55 PM, Carl Denk wrote:

> Last week, I picked up 40 gallons of off road (no highway tax) diesel
> fuel for our tractor at the local distributor that services farmers  
> and
> businesses. I pumped from a 3000 gallon above the ground tank with a
> pump/meter unit mounted on top. This was the exception to the
> submersible tank setup. The nozzle tube was at least 1" diameter, no  
> way
> could you get it into a car fill point. :)


If it was the "standard" larger diesel nozzle size used by 18- 
wheelers, the Volkswagen diesel cars not only can handle the larger  
diameter nozzle, but also have a special air return system (a valve  
activated by the larger nozzle being inserted opens an air "escape"  
valve that allows air to escape at a much faster rate from the fuel  
tank up through a tube to that plastic valve in the filler port.

This allows you to fill up at the much bigger nozzle pumps the trucks  
use at a horrendously fast rate.  But you'd better watch it closely  
because it'll easily overfill and cause a spill at those pumps.

You have to love VW engineers for including it, though.

Since this air return system also incorporates a small pocket of air  
molded into the top of the fuel tank, many VW diesel drivers will  
carry a few disposable latex gloves or similar and on long trips where  
they want the maximum fuel in the tank during a fill-up, they'll reach  
in with a finger and push the air valve open while using a regular  
"car sized" small diesel nozzle, which will allow for "topping off"  
the tank with quite a bit more fuel into that "air space" at the top.

It's a pretty significant amount of fuel, but I don't remember how  
much.  I didn't have gloves with me the day I messed with it on my  
wife's Jetta Wagon, and I smelled like diesel for the rest of the day,  
even with trying to wash it off... gloves highly recommended.  :-)

Meanwhile the thing's highway fuel economy is so high, that even if I  
watch my water and/or coffee intake when on a long road trip, the  
diesel car will always outlast my bladder -- "extra fillup" or a  
regular one.   One tank of fuel from just south of Mt. Rushmore, South  
Dakota to the south suburbs of Denver, CO is WAY too long to be in the  
driver's seat... I didn't even attempt it.  But I didn't have to fill  
up...

Not particularly interested in finding out what Deep Vein Thrombosis  
and pulmonary edema from a blood clot passing through my heart is like.

Only really messed with filling the car with the larger "truck" pumps  
once.  It was full so fast, it was amazing, even only opening the pump  
to the first "notch" on the locking mechanism.  WHOOOOSH.  Nice if you  
had to, but not really worth the nervousness that goes with it.

--
Nate Duehr
nate@natetech.com



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