Q Tip

I have an issue w/ my '03 4.6 with 37,000 miles that I'd like to bring to the forum. If my truck sits for several days, and I crank her up, I hear what sounds like a loud rush of air from the engine compartment. It only lasts as long as it takes the truck to start.

If I am driving it during the day and crank it several times, I never hear the noise. Only once on the first crank of the day.

The noise "seems" to come from the passenger side from where I sit in the drivers seat.

Just wondering if anyone could point me to where to look.

Thanks much.

I'm not a mechanic, just a barely competent gov't machinist....did a search but found a lot of stuff I don't even know what it is, phazer beams, moon rocks, anti-wetback valves, and all such as that.