It was very cold today (around 12 degrees). When I started my expy I noticed a rattle noise under the hood. It went away after I drove for about 10 miles....Any suggestions?

John B.
1998 Expy XLT 4.6
Alteeza Chrome tails
Ractive superflow intake
Billet grill combo(coming soon)

 

Assuming you are not hearing the LLS air compressor, it could be valve tappets due to cold affecting oil viscosity. In cold weather it is very important to have both clean oil and filter, and the right viscosity in the engine. Mine started and ran fine last week in -25 weather using fresh Motorcraft Super Premium Blend at 5w-30 viscosity. If you are going to experience that kind of cold or colder on a regular basis (I don't) use a lower viscosity oil per Ford recommendations.