'04 PD Fuel Cooler in Fuel Return Line

\'04 PD Fuel Cooler in Fuel Return Line

While putting snow tires on my new '04 TDI Jetta I noticed that there is a fuel to air heat exchanger in the fuel return line to the tank. It is an aluminum heat sink about 12 inches long by 4 inches wide mounted underneath the car directly below the passenger side rear seat. It is in series with the blue fuel return line. Has VW always used such a heat exchanger to cool the fuel in the return to the fuel tank? It doesn't seem like this is would be good for cold weather driving.

\'04 PD Fuel Cooler in Fuel Return Line

My '02 AT had the fuel cooler but I think the Std. did not.

My guess is that they decided to put it on the '04 due to the fact that the bypass fuel will probably get warmer as it is being transferred through galleries inside the head and the rigid lines on the exterior of the valve cover don't help to keep the fuel cool either.

I guess that the heated fuel will expand and the tank could overflow.

Sound plausible?

\'04 PD Fuel Cooler in Fuel Return Line

The fuel is quite hot, too. After I was driving my '04 Jetta for a while I felt the fuel cooler and it was too warm (hot) to keep my hand on it. It was about freezing outside too. I could just imagine how hot that cooler would feel on a 95 deg. F summer day after a highway drive.

--Nate