RIDEX Short Thermostat & Housing – MX-5 Mk3 NC • 316T0273

RIDEX 316T0273 Short Thermostat & Housing – MX-5 Mk3 NC

Replacement RIDEX short-type engine coolant thermostat and housing assembly for selected Mazda MX-5 Mk3/NC 1.8 and 2.0-litre petrol models.

Critical chassis-number restriction: For Mazda MX-5 applications, this short thermostat/housing is confirmed only for vehicles with chassis numbers 115785 to 124657 inclusive. Do not order solely from the registration year.

MX-5 NC vehicles up to chassis number 115784 and from chassis number 124658 onward use the longer thermostat/housing arrangement instead. RIDEX 316T0250 is the corresponding long-type unit listed by MazSpec for those vehicles.

The thermostat regulates coolant circulation between the engine and radiator. When the engine is cold it restricts radiator flow to help the engine reach normal operating temperature. As coolant temperature reaches the thermostat's calibrated opening point, the valve opens and allows greater coolant circulation through the radiator.

A faulty thermostat may stick open or closed. A thermostat stuck open can cause slow warm-up, low operating temperature and poor heater performance, while one stuck closed can contribute to overheating, excessive cooling-system pressure and potentially serious engine damage.

• Part type: Engine coolant thermostat with housing
• Design: Short-type MX-5 NC thermostat housing
• Opening temperature: 90°C
• Diameter 2: 23 mm
• Housing height: 39 mm
• Housing material: Synthetic material / plastic
• Seal: Included
• Approximate weight: 0.274 kg
• EAN: 4064138035767
• Quantity supplied: 1 thermostat and housing assembly with seal
• Brand: RIDEX
• Part No.: 316T0273

Fitment advice: MazSpec confirms the short 316T0273 housing specifically for Mazda MX-5 Mk3/NC vehicles within chassis range 115785–124657 inclusive. Both 1.8 and 2.0-litre petrol engines appear in the associated MX-5 application data. Always check the vehicle chassis number before ordering because visually similar long and short thermostat housings were used during the early NC production period.

Common replacement reasons: Engine running too cold, slow warm-up, poor cabin-heater performance, overheating, erratic coolant temperature, coolant leakage around the housing or seal, or replacement during wider cooling-system repairs.

Other items to consider: Inspect the coolant hoses, expansion tank, radiator, water pump, radiator cap and coolant condition. Any evidence of overheating should be investigated rather than assuming the thermostat is the only cause.

Useful tools / consumables: Socket and ratchet set, torque wrench, coolant drain container, suitable hose-clamp tools, fresh coolant of the correct specification and equipment for correctly bleeding the cooling system.

Difficulty guide: DIY Difficulty: Moderate. The cooling system must be opened and subsequently refilled and bled correctly. Access and hose removal can also become more difficult on older vehicles.

Why RIDEX? RIDEX cooling-system components provide a cost-effective aftermarket replacement manufactured to application-specific dimensions and temperature specifications. This assembly combines the thermostat, synthetic housing and seal in one replacement unit.

What’s in the box: One RIDEX short-type thermostat and housing assembly with seal. Coolant, hoses, fasteners and installation tools are not included unless physically supplied with the component.

Installation notes: Allow the engine to cool completely before opening the cooling system. Confirm the chassis number and compare the original thermostat housing length before dismantling the vehicle. Drain sufficient coolant, disconnect the relevant hoses and remove the original housing. Clean the mating surfaces carefully and install the replacement with the supplied seal without damaging or pinching it. Tighten the housing fasteners evenly to the applicable specification. Refill with the correct coolant mixture, bleed the system fully and inspect for leaks while monitoring engine temperature during warm-up.