| Frame rust/rot | Road salt, trapped mud, poor undercoating | Probe/repair sections; avoid heavy patchwork | $2000-12000 |
| Body mount corrosion | Moisture trapped at mount cups and seams | Replace mounts; weld mount cups as needed | $800-4000 |
| Windshield frame rust | Seal traps water; prior glass installs | Remove glass; cut/repair metal; reseal | $800-3500 |
| Rear crossmember rot | Mud/salt accumulation; towing loads | Replace/repair crossmember; treat inside rails | $1200-6000 |
| Floor pan rust/wet carpets | Heater core leaks or clogged drains | Fix leak source; patch pans; dry insulation | $300-3000 |
| TD42 low oil pressure | Worn bearings, tired pump, thin oil, sludge | Confirm with mech gauge; rebuild bottom end | $3500-12000 |
| Excessive blow-by | Ring/cylinder wear from dusting or high miles | Compression test; rebuild; fix intake sealing | $5000-15000 |
| Overheating under load | Clogged radiator, weak fan clutch, bad stat | Radiator+clutch+stat; verify shroud and cap | $600-2200 |
| Cracked cylinder head | Chronic overheating; poor coolant maintenance | Pressure test; replace head; address cooling | $3500-9000 |
| Heater core failure | Age corrosion; old coolant; electrolysis | Replace core; flush system; new hoses/clamps | $600-1800 |
| Injection pump leaks | Aged seals; ULSD shrinkage; shaft wear | Reseal/rebuild pump; set timing on bench | $900-2500 |
| Air ingress hard start | Cracked primer, filter head, return hoses | Replace filter head/hoses; add clear line test | $150-700 |
| Injector wear/poor spray | High hours; dirty fuel; overdue service | Pop test; rebuild/replace nozzles; set pressures | $400-1200 |
| Turbo kit overfuel/EGT | Aftermarket turbo with no EGT control/tune | Install EGT/boost; tune pump; proper intercooler | $800-5000 |
| Dusting engine wear | Leaky airbox, poor snorkel sealing, offroad dust | Inspect intake for silt; reseal; rebuild if worn | $200-15000 |
| Manual synchro grind | Worn 2nd/3rd synchros; wrong oil; hard use | Correct oil; rebuild gearbox if persistent | $1200-4500 |
| Auto trans overheating | Towing, big tires, no cooler, old fluid | Add cooler/temp gauge; service or rebuild | $300-4500 |
| Transfer case pops out | Worn detents/forks; linkage misadjusted | Adjust linkage; rebuild t-case if worn | $300-2500 |
| Front swivel hub leaks | Worn knuckle seals; overfilled diff; age | Full knuckle rebuild; set preload; new bearings | $600-1800 |
| Wheel bearing failure | Neglected grease; water ingress; wrong preload | Replace bearings/seals; set preload correctly | $300-1200 |
| Death wobble/shimmy | Worn tie rods, panhard bushes, caster off lift | Replace wear parts; align; caster correction | $400-2500 |
| Steering box leak/play | Sector shaft seal wear; internal wear | Rebuild/replace box; flush PS; check pump | $600-2200 |
| Brake line corrosion | Salt exposure; old fluid; poor underbody care | Replace hard lines; flush fluid; inspect hoses | $500-2500 |
| Seized front calipers | Corrosion; torn boots; infrequent fluid changes | Rebuild/replace calipers; new pads/rotors | $400-1400 |
| Vacuum pump/booster weak | Pump wear/leaks; booster diaphragm aging | Replace pump/booster; check vacuum lines | $500-1800 |
| Alternator failure | Heat/oil contamination; worn bearings/diodes | Rebuild/replace alternator; fix oil leaks | $250-900 |
| Starter slow crank | Worn contacts; bad grounds; heat soak | Rebuild starter; upgrade cables/grounds | $200-700 |
| A/C weak or inop | Old seals, leaking condenser, worn compressor | Leak test; replace parts; convert/charge properly | $400-2000 |
| Window regulator failure | Worn guides/cables; tired motors | Replace regulator/motor; lube channels | $150-600 |
| Rear door sag | Worn hinges; heavy spare/tire carrier loads | Replace hinge pins; adjust latch; reinforce if needed | $150-800 |
| Diff pinion seal leaks | Age; vent blockage; worn yoke surface | Replace seal; clear vent; sleeve yoke if grooved | $200-700 |
| Locker actuator failure | Corrosion, seized motor, broken vacuum lines | Service actuator; replace lines; retrofit manual | $300-2000 |
| Cooling gauge lies | Damped gauge/sender; wiring resistance | Verify with IR/scan; replace sender; add real gauge | $50-400 |