How to PROPERLY Repair a Rust Hole in your Car or Truck (DIY for Beginners)

Summary by Krater

A complete step-by-step tutorial on how to permanently repair a rusted-out floorboard in a car. The video covers finding the source of the leak, cutting out rusted metal, fabricating and fitting a new patch panel, butt-welding it in place with a MIG welder, and sealing and painting the metal to prevent future rust.

From the video

Answers: How do you permanently repair a rusted car floorboard?

• Rust repair in car floorboards
• Finding and fixing automotive water leaks
• Using a sheet metal nibbler
• MIG welding thin sheet metal
• Butt welding vs lap welding floor pans
• Using a copper heat sink for welding burn-throughs
• Rust prevention and sealing

What it concludes

• Removing all rust down to shiny bare metal and applying a rust barrier paint is necessary to prevent future rust.
• Using a full-face respirator with P100 filters is recommended over a basic N95 dust mask when grinding rust and undercoating.
• A 90 amp flux-core welder with 0.030-inch wire cannot weld metal thinner than 22 gauge without burning through, making a gas MIG welder necessary for thin automotive sheet metal.
• Butt welding is superior to lap welding for floorboards because it creates a seamless joint with no gap for moisture and future rust, although it requires precise fitting.
• Prep-cleaning metal surfaces by sanding off all paint, rust, undercoating, and seam sealer with a wire wheel is critical to prevent weld contamination and cracking.
• Using a piece of copper pipe or flat copper as a heat sink underneath holes during welding absorbs excess heat and allows easy filling of burn-throughs.