Floor Pan Patch (Driver + Passenger)
Difficulty 3/56–16 hrs$100–4001984-1990, 1991-1995, 1996, 1997-2001
Short answer
Floor pans rot under carpet from cowl leaks and seam-sealer failure. Patch with 18-gauge steel cut to fit, or buy pre-formed XJ floor patches from KEY Parts / Magnum / Tabco.
XJ floor pans rot in three predictable areas:
- Driver's footwell, immediately rearward of the firewall, on the right side of the brake/clutch pedal — water from the cowl drain runs here.
- Passenger footwell, mirror location.
- Rear seat foot area, under rear cargo.
Pre-formed patches are available:
- KEY Parts XJ driver/passenger floor patch: ~$80 each, 18-gauge steel, includes flange for spot welding.
- Tabco / Magnum: similar quality, varies in shape coverage.
- Auto Rust Technicians: also makes XJ-specific patches.
For smaller rust holes (<6" diameter), 18-gauge sheet steel cut to size with a flange beat into it works fine. Larger areas need the full patch.
Process:
- Pull carpet (see carpet replacement entry — good time to do both).
- Cut out rust with cut-off wheel, going 1" beyond visible damage.
- Treat surrounding metal with phosphoric acid.
- Fit patch. Mark and cut for tight fit (1/16" gap or less).
- Tack weld at corners, then stitch weld around perimeter with MIG. Avoid blow-through with short bursts on thin metal.
- Grind welds smooth. Apply seam sealer over weld inside and underside.
- Coat underside with rubberized undercoating (3M, Por-15, or Raptor Liner).
- Inside floor: lay sound deadener (see Dynamat entry) then carpet.
While carpet is out: address the cowl drains (see cowl repair) — they're WHY the floor rotted.
Why it works
- addresses common rust spot
- good time to do sound deadening
Trade-offs
- requires welding
- must fix cowl drains too
Tools required
- MIG welder
- cut-off wheel
- grinder
- sheet metal shears
- trim tool
Parts
| Part | Vendor | Est. price |
|---|---|---|
| KEY Parts XJ floor pan patch (each) | KEY Parts | ~$80 |
| 18-gauge sheet steel 12x24 | Home Depot / Speedway | ~$25 |
| Por-15 undercoating | Por-15 | ~$30 |
Sources
Related
- Cowl Repair (Rusty Cowl Drain Tubes)
- Rocker Panel Replacement
- All Jeep Cherokee XJ guides & tools
- Browse the full DIY database
Written and maintained by an AZ wheeler and driveway wrencher. How we source guides. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.