heat exchanger

[vernj4]

Just changed the engine oil on my new-to-me 2004 D/A with lly engine. While under the truck, noticed a heat exchanger mounted just forward of the fuel tank. What is this unit for? Thanks for your response.

[DmaxMaverick]

It's the fuel return cooler.

[Mark Rinker]

...also a rock catcher, snow/ice accumulator, etc... :)

[Duramaster]

Wash it out periodically with the garden hose or just blow it out with compressed air.