Showing specs for all NA & NB Miatas

Thermostat sub valve full-open lift — minimum (NA6)

0.06 in (1.5 mm) minimum at 212 °F (100 °C)1.5 mm {0.06 in} minimum at 100°C {212°F}

Factory manualTaken from a Mazda factory workshop manual, with page citation.
Procedure

Factory two-stage thermostat with separate main and sub valves. Visually check valve is airtight, then place thermostat and thermometer in water and heat the water. Do not apply these two-stage specifications to an aftermarket single-stage thermostat. Minimum lift at the specified full-open temperature.

Applies to
  • NA 1990–1993 (B6) — Other years inferred from 1990 factory evidence.
  • Verified in: 1990 Mazda MX-5 Miata Workshop Manual