I live in Ohio right in the snow belt. I just bought a 2007 Grand Cherokee. Underneath the driver side passenger door is rust bubbling. What's the best way to prevent it from further rusting ?? Thanks !

 

You may have a "slag" inclusion in that piece of metal, as in junk included in the metal when it was formed. It happens because cars are not made with virgin metal. I had a Chevy with one of those in the middle of the driver's door that rusted on BOTH sides of the panel. The only way to stop those is to cut it out and weld in a new piece of metal.

BTW, my '00 WJ started life in Washington, PA and I bought it here in Syracuse 4 years ago. It hasn't shown ANY rust yet. The jeep is white and the only rust I've found is a slight tinge of brown on the cut edges of the lap welds underneath.

 

Exactly where mine is. It's a 2007 and spotless. Just that one door !!!

 

You're going to have to sand it down and see if the actual metal is black. That's an indication of in inclusion. No matter how you repair or paint it, it will reappear. Cut it out!

I had a friend who bought a '69 Pontiac Firebird 400 new. After about a year, he wracked up a front fender and bought a new one directly from GM. It was primed black and because his car was white, he decided to remove the primer and prime it white. You would not believe the condition of the metal underneath! It had draw lines and inclusions in it that were incredible! Somehow, he got GM to give him another one, which he just primed white over the black.