Truck, classic-car, and fleet undercarriages collect a paste of road grime, engine oil, transmission seep, undercoating overspray, and salt that no pressure washer reaches and no degreaser fully lifts. Restoration shops and fleet maintenance teams increasingly use dry ice blasting because it gets the frame and underbody back to bare paint or bare metal without added process water in places water shouldn't go.
Why the undercarriage is a dry-ice job
Three reasons. First, the substrate is mostly painted steel, aluminum, hard rubber, and wiring loom — all of which tolerate dry ice and none of which appreciate prolonged water exposure. Second, the contamination is carbonized oil and bonded grime that water blows around but doesn't lift. Third, restoration buyers want to see the original surface beneath — including stamping marks, factory inspection paint, and date codes — which abrasive media obliterates and dry ice preserves.
What we clean
- Frame rails, crossmembers, and suspension mounts
- Engine bay, bell housing, oil pan, and transmission case
- Differential and transfer case housings
- Brake backing plates, calipers, and dust shields
- Wiring looms, vacuum lines, and brake/fuel hard-lines
- Fuel tank straps and tank surfaces
- Body undersides, floor pans, and rocker undersides
What we don't touch
- Seized fasteners — we'll clean around them; we don't do disassembly
- Heavy structural rust scale — that's a media job, not a dry-ice job
- Catalytic converter internals or exhaust gaskets at operating temp
Restoration vs fleet scoping
Restoration is a one-off per vehicle, usually scoped as a half- or full-day with the vehicle on a lift or rotisserie. We work with the shop's painter so the cleaned underbody goes straight into seam-seal and coating without re-contamination. Fleet undercarriage cleaning is usually a recurring route — single tractor or trailer in 45–90 minutes, scheduled into the PM window so the unit is back in service the same day.
Documentation
For insurance restoration and concours-bound builds we deliver before/during/after photo logs, parts identification, and any incidental observations (cracked mounts, weeping seals, missing hardware) so the shop foreman can fold it into the build sheet.