Mesozoic

Since I rarely open the rear passenger-side door, I was surprised to hear a loud 'sloshing' when opening and closing it last week.
I pulled off the oval rubber plug at the bottom and about a quart of water poured out. My question, is the window seal or door seal leaking? Both appear to be tight and flush. Anyone else experience this? I left the little plug off and safely stored it in the glove box. So far, no more sloshing after rain or washing. I'm assuming water comes in but drains out. 2017 Raptor. Thanks for any and all ideas.

Silver-Bolt

THe drain hole is likely plugged. By design water will get in the door. There are drain holes in the lower corners of the doors. They frequently get clogged. Use a wire and clean them out. That will allow your door to drain like the other three.

Delta1166

Pointy end of a plastic zip-tie inserted into the slots at bottom front-edge and rear of the door panel [Poke it both left-to-right & also upwards] will clear debris from the slots & allow the water to drain out better (when you open the doors). Likewise there's a small hole in the rubber weatherstrip about midway across the door panel that when poked also will help drain any water. Try & clean these points every few months for best results.

Most likely source of leak is the hi-pressure rinse or the forced air dryer at a carwash blowing water between the weatherstrip & window.