What are the most common Datsun 240Z problems?
According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1970-1973 Datsun 240Z has 7 documented issues. The most frequently reported are: Unibody Rust: Frame Rails, Floor Pans, Battery Tray & Doglegs, L24 Flat-Tappet Cam Wear & Brass Valve Seats on Modern Fuel/Oil, Marginal Cooling System & L24 Overheating. Of these, 3 are rated critical and should be addressed promptly.
Is the Datsun 240Z reliable?
The 1970-1973 Datsun 240Z has 7 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 3 issues are rated critical: Unibody Rust: Frame Rails, Floor Pans, Battery Tray & Doglegs and L24 Flat-Tappet Cam Wear & Brass Valve Seats on Modern Fuel/Oil and Marginal Cooling System & L24 Overheating. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
How much does it cost to fix common Datsun 240Z problems?
Repair costs for known Datsun 240Z issues range from $150 to $12,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Unibody Rust: Frame Rails, Floor Pans, Battery Tray & Doglegs, typically costs $1,500-$12,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
What year Datsun 240Z is the most reliable?
Reliability varies across model years of the Datsun 240Z. Based on documented issues, problems are most commonly reported in earlier model years. Au7o recommends checking the specific known issues for your target year before purchasing, and having a pre-purchase inspection performed by a qualified mechanic. Our known issues database covers the 1970-1973 Datsun 240Z with 7 documented issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports.
What is the 1970-1973 Datsun 240Z Unibody Rust: Frame Rails, Floor Pans, Battery Tray & Doglegs?
The S30 240Z left the factory with minimal rustproofing and several built-in moisture traps, so rust is the single biggest weak point restorers face. Corrosion attacks the structural front frame rails, the floorpans, the battery tray (acid + trapped water accelerate it), the rear… Repairs typically run $1,500-$12,000. Severity: high.
What is the 1970-1973 Datsun 240Z L24 Flat-Tappet Cam Wear & Brass Valve Seats on Modern Fuel/Oil?
The L24 uses a flat-tappet (sliding-contact) overhead camshaft riding directly on rocker arms — a design that depends on the high ZDDP (zinc/phosphorus) levels of 1970s oil. Modern low-ZDDP, emissions-friendly oils don't provide enough anti-wear film, so a freshly rebuilt or hard… Repairs typically run $200-$2,500. Severity: high.
What is the 1970-1973 Datsun 240Z Marginal Cooling System & L24 Overheating?
The L24's factory cooling system is marginal by modern standards, and 50 years of scale, aging brass/copper radiators, tired water pumps, clogged passages and a sludged block leave many 240Zs prone to overheating — especially in traffic, in hot climates, or with any performance b… Repairs typically run $400-$1,800. Severity: high.
What is the 1970-1973 Datsun 240Z Outdated Rear Drum Brakes (Disc Conversion Candidate)?
The 240Z uses front discs but REAR DRUM brakes, and after decades of sitting the whole system is usually tired: the rear drums fade with repeated/heavy use, the wheel cylinders leak, the single-circuit-era hardware and rubber hoses are perished, and the proportioning is dated. Fo… Repairs typically run $500-$2,500. Severity: medium.
What is the 1973 Datsun 240Z Troublesome '73 Flat-Top Hitachi SU Carburetors?
For the 1973 model year (emissions-era), Datsun switched the twin Hitachi SU carbs from the proven HJC46W 'round-top' design to the HMB46W 'flat-top' with an integrated (HIF-style) float chamber. These flat-tops are notoriously hard to tune, far less reliable than the round-tops,… Repairs typically run $400-$1,500. Severity: medium.
What is the 1970-1973 Datsun 240Z Perished Suspension Bushings & Differential/Mustache-Bar Mounts?
After 50 years every rubber bushing and mount on a 240Z is hardened, cracked or collapsed — control-arm and tension-rod (T/C) bushings, sway-bar bushings, the transverse-link mounts, plus the R180 differential front mount and 'mustache-bar' rear diff insulators and the transmissi… Repairs typically run $300-$1,500. Severity: medium.
What is the 1970-1973 Datsun 240Z Weak 40A Alternator & Failure-Prone External Voltage Regulator?
The 240Z left the factory with only a ~40-amp alternator and a crude points-type EXTERNAL mechanical voltage regulator. The mechanical regulator can't hold a stable output by modern standards, its contacts pit and stick with age, and it commonly causes under- or over-charging, fl… Repairs typically run $150-$450. Severity: medium.
