Cargo Area Floor Rust
Cargo floor rusts behind the rear wheel wells and along the spare tire well. Common from snow/road salt or a leaking rear hatch seal. Patches available; full replacement requires good donor.
The cargo area floor of an XJ is single-skin stamped steel with stiffening ribs. Water collects in the corners (especially behind the rear wheel wells under the cargo carpet) and rots from underneath.
Diagnostic: lift the cargo carpet and the cardboard cargo floor. Press a screwdriver against suspicious areas. Flake = rust through.
Repair options:
(1) Patch panels (18-gauge steel cut to shape): for localized rust, cut out and weld in patches as with floor pan repair.
(2) KEY Parts cargo floor patch panels: pre-stamped for the corners + spare well lip. ~$50-80 each.
(3) Full cargo floor replacement: requires a parts XJ. Cut the entire cargo floor out of a donor (preserve frame rail connection points), graft into yours. Big job — 20-40 hours. Only do this if the floor is full Swiss cheese.
Key causes to fix:
- Rear hatch seal: replace if cracked. Pour water test from inside the cargo with the hatch closed.
- Rear tail light gaskets: water enters through corroded gaskets, runs down inside the quarter panel onto the cargo floor.
- Spare tire well drain plug: a 1" rubber plug at the bottom of the spare well. Often missing — water collects in well and rots through.
- Cargo carpet retains moisture — remove and dry after every wet trip.
While you're in here, install a Plano-style storage bin in the spare well (if running spare elsewhere), or build a drawer system.
Why it works
- preserves cargo functionality
- stops spread to frame rails
Trade-offs
- welding overhead is tedious
- many causes to address
Tools required
- MIG welder
- cut-off wheel
- grinder
- trim tool
Parts
| Part | Vendor | Est. price |
|---|---|---|
| KEY Parts cargo floor corner patches | KEY Parts | ~$65 |
| 18-gauge sheet 24x36 | Speedway Motors | ~$35 |
| Spare well drain plug (rubber, 1") | Hardware store | ~$2 |
Sources
Related
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.