When I don't start my truck (07 F-150, 5.4L) for over 24 hours I get a weird sound when I start it. It sounds normal cranking but when it fires up and I let go of the key I get almost a short (1 second or less) grinding type sound... similar (but not quite) to the sound you might get if you tried to turn the key when the engine was already running. Then it will not make that sound again unless it sits for a day or more. Any ideas? TIA

 

Sounds like the starter bendix isn't releasing soon enough.

 

You know, I may have the same sound on my '03. If I let the rig set for a couple of days, and lately I do, it will let out a growl at startup, just for a second, like you indicated. Only on the first time I hit the starter. If you key-off then re-start it will not do it a second time. My truck has done this intermittently since it was new. I have >90K trouble free miles so far (knock on wood.) I just have figured that it is one of my trucks little quirks.