IsItAGoodCar
Reliability Guide

Common Problems with the
1973 Datsun 240Z / 260Z

We've identified 4 known issues that can affect the 1973 Datsun 240Z / 260Z. 2 of these are serious faults that could be expensive to repair.

4
Known Issues
2
Serious
2
Moderate
0
Minor

All Known Issues

Structural Corrosion (Rust)

SeriousBodywork & Rust

The S30 chassis has many hidden box sections where moisture traps and eats the metal from the inside out. Frame rails, battery trays, and floor pans are the most common failure points.

Est. Repair Cost: £5,000–£20,000+
Warning Signs:

Bubbling paint, Soft spots in floor/sills, Doors not aligning (suggesting chassis flex), MOT failure for structural rot

What to Inspect:
  • Magnet test on sills and arches
  • Hammer tap on frame rails
  • Check under the battery tray for acid/water damage
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Overheating & Head Gasket Failure

SeriousCooling System

Older L24/L26 engines can suffer from silt buildup in the radiator or blocked coolant passages in the block, leading to localized overheating and warped heads.

Est. Repair Cost: £1,000–£3,000
Warning Signs:

Temp gauge climbing in traffic, White smoke from exhaust, Mayo-like sludge under oil cap

What to Inspect:
  • Condition of coolant (should be clean)
  • Ask when the water pump/radiator was last replaced
  • Test for exhaust gases in coolant
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Carburetor & Fuel System Issues

ModerateFuel System

The Hitachi-SU carburettors require regular maintenance and adjustment. Worn needles, vacuum leaks and gummed-up passages cause flat spots, poor idle and hesitation. Parts are hard to source, with many owners converting to Webers.

Est. Repair Cost: £200–£600
Warning Signs:

Hesitation on acceleration, Stalling at idle, Rich or lean running, Strong fuel smell

What to Inspect:
  • Check for smooth throttle response through the range.
  • Look for fuel leaks around carburettors.
  • Inspect fuel lines for perishing.
  • Ask if Weber conversion has been done.
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Wiring Loom Degradation

ModerateElectrics & Electronics

After 45+ years, the original wiring loom becomes brittle. Corroded fuse connections, cracked insulation and perished earth straps cause intermittent electrical faults throughout the car.

Est. Repair Cost: £100–£500
Warning Signs:

Intermittent lighting failures, Gauge erratic behaviour, Flickering dashboard lights, Blown fuses

What to Inspect:
  • Inspect fuse box for corrosion.
  • Check all earth points for clean metal contact.
  • Test all electrical systems including lights and gauges.
  • Consider a relay upgrade for headlights.
Verified by IsItAGoodCar Research Team

Buying Tips for 1973 Datsun 240Z / 260Z

  • ✓Rust is the absolute priority; meticulously inspect the floor pans, battery tray, spare wheel well, and chassis rails.
  • ✓Check the condition of the twin Hitachi (SU-style) carburetors; they require specialist balancing for the engine to run smoothly.
  • ✓Verify the health of the manual gearbox, listening for worn synchros, particularly when shifting into second gear.
  • ✓Examine the interior dashboard for cracks, as original uncracked dashes are incredibly rare and expensive to replace.
  • ✓Look for evidence of poor previous restorations; lots of body filler (Bondo) is a common cover-up for severe rot.
  • ✓Check the electrical system, as old wiring looms can become brittle and cause erratic issues with lights and gauges.
Check a 1973 Datsun 240Z / 260Z by Registration