Is the popping sound from all the door speakers, or just one of them? Could water be getting into a crack in the speaker wiring insulation from one particular door?
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E