Took me 11 days to chase down a water leak in a 2016 F-150 and it was a $6 grommet the whole time
This one still burns me up. Customer brings in a 2016 F-150 after a rear end hit, we replace the tail light housing, seal up the bed seams, the whole deal. Two weeks later he's back saying the carpet behind the driver seat is soaked after every rain. I pull the interior, dry it out, run the hose on it for 45 minutes and see nothing. Come back next morning, puddle again. I tore out the headliner, checked the sunroof drain, resealed the third brake light twice, even pulled the rear window and reset it with fresh butyl. Nothing. Day 11 I'm sitting in the truck with a flashlight while my kid runs the hose and I finally see it: a tiny drip coming down the inside of the firewall from a body plug grommet that got knocked loose when we pulled the fender during the original repair. Six dollar part, ten seconds to snap back in. I had 14 hours of labor into a leak that a $6 grommet caused. Now I pressurize the cab and use soapy water on every plug before I ever hand a wet car back. Anybody got a better leak finder trick than the hose and flashlight routine? I'm all ears.