According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1994 Toyota 4Runner has 5 documented known issues, with 3 rated critical. The most serious are 3.0L 3VZ-E V6 Head Gasket Failure (Coolant Loss, White Smoke, Rough Idle) — SSC V06 / Extended Warranty ($200-$2,500 repair), 3.0L V6 (3VZ-E) Head Gasket Failure — Toyota Special Service Campaign V06 ($1,400-$2,800 repair) and Rocker Panel, Rear Wheel-Arch and Pinch-Weld Rust ($600-$3,500 repair). Across all issues with published estimates, repair costs range from $150 to $3,500. DIY maintenance guides at au7o.io.