Parts for your 2013 Mazda Premacy-Radiator cap

2013 Mazda Premacy radiator cap: what it does, where it fits, and when to replace it

On the 2013 Mazda Premacy (CW series), a radiator cap is absolutely used and relevant. Mazda’s factory workshop manual for the Premacy/Mazda5 CW platform includes a “Radiator Cap Inspection” procedure with a specified pressure range (approx. 88–118 kPa), and Mazda’s electronic parts catalog for this model lists a dedicated pressure radiator cap for the cooling system. Those technical sources confirm the vehicle relies on a proper pressure cap fitted to the cooling system, rather than a capless or sealed “header-tank only” setup.

On this Premacy, the radiator cap’s job is to hold pressure in the cooling system so the coolant’s boiling point is raised, keeping temperatures stable when the engine’s working hard under the Kiwi or Aussie sun. The cap also has a vacuum valve that lets coolant be drawn back from the overflow bottle as the engine cools down, preventing hoses from collapsing and keeping the system topped up.

When servicing the Premacy, it’s smart to treat the radiator cap like any other wear item. A tired spring or cracked seal can cause slow coolant loss, hotter running, or that tell‑tale sweet smell after a drive. If the car has overheated, the cap cops a hammering and should be tested or replaced.

• Inspection tips: Look for perished rubber seals, rust or crust around the neck, and a sticky or weak spring action. If a cooling system pressure test won’t hold within spec, suspect the cap.
• Replacement advice: Use the correct pressure rating stamped on the cap (around 0.9–1.2 bar for this model) and the proper neck type. Cheap, wrong‑spec caps can cause more grief than they save.
• Good practice: Replace the cap proactively every 3–5 years or 60,000–100,000 km, especially in hot climates or if coolant changes were skipped.
• Safety: Only remove the cap when the engine is stone cold. Wrap it in a rag and release it slowly to avoid a hot gush.

Whenever the cap is off, check coolant level and condition, use the correct long‑life coolant mix, and bleed air properly after any cooling system work. A healthy cap is cheap insurance for a long‑lived Premacy engine.

FAQs

Does the 2013 Mazda Premacy actually have a radiator cap?
Yes. The CW‑series Premacy/Mazda5 uses a pressure radiator cap as part of its conventional pressurised cooling system. It’s typically on the radiator neck, with a separate overflow bottle alongside.

What pressure rating should the cap be?
Mazda’s workshop spec for this platform is roughly 88–118 kPa (about 0.9–1.2 bar). Always match the rating stamped on the original cap or use a genuine/OE‑equivalent part specified for the 2013 Premacy.

When should the cap be replaced?
Inspect it at every service. Replace if seals are cracked, the spring feels weak, there’s staining around the neck, after any overheating incident, or as preventative maintenance every few years or around 60,000–100,000 km.