I hear this noise quite often, and I haven't seen anyone here discuss it.

Every once in a while, often (but not always) when the engine is cold and I make a quick start, I hear this bizarre sound inside both doors (louder on the passenger side) and up into the sides of the engine compartment and sometimes behind me. It sounds like a million little pebbles or tiny raindrops raining down inside the door. The noise will last maybe 10 seconds.

Anyone heard this? Is this some weird hydraulics thing?

 

Maybe a fuel leak going to your miniature rotary engines in each door, for your motorized windows & mirrors?

jk

Uh, I haven't heard of this one before...