Parts for your 2018 Toyota Vitz|yaris-Radiator cap

Radiator cap for 2018 Toyota Vitz/Yaris

Technical documentation confirms a radiator cap is fitted to the 2018 Toyota Vitz/Yaris. The Toyota Owner’s Manual for the 2018 Yaris Hatch (AU/NZ) warns against removing the radiator cap when hot and shows the cap location, the Toyota Repair Manual for the XP130 series includes “Inspect Radiator Cap Sub-Assembly” with an opening pressure around 80–110 kPa (about 0.8–1.1 bar). Toyota’s Electronic Parts Catalogue also lists a pressure cap for common 2018 Vitz/Yaris engines (e.g., 1KR-FE, 1NR-FE). So, yes—this model uses a conventional pressurised radiator cap.

On the 2018 Vitz/Yaris, the radiator cap does more than just close the top of the radiator. It seals and pressurises the cooling system so coolant can run hotter without boiling, keeping the engine steady on scorching Aussie or Kiwi days. The spring-loaded valve vents excess pressure to the overflow bottle when things heat up, and the vacuum valve pulls coolant back in as the engine cools, stopping hoses from collapsing and preventing air pockets.

Look after the cap and it’ll look after the engine. At every service, it’s smart to check:

• Rubber seals for cracks, flattening, or swelling
• Spring tension and smooth valve movement
• Any white crust, rust, or sludge around the neck and cap
• Hoses that collapse after cool-down (a sign the vacuum valve is sticking)

If a pressure tester is handy, have the cap tested to the spec (about 80–110 kPa). Replace the cap if it won’t hold pressure or if seals are tired. Many technicians treat the cap as a consumable—typically replaced around 4–5 years or 80,000–100,000 km, or sooner if there are symptoms like random overheating, coolant loss into the overflow bottle, or hard upper hoses after a short drive.

Use a quality 1.1 bar Toyota-type cap (commonly stamped 108 kPa) to match the system. Avoid dropping to 0.9 bar or jumping to 1.3 bar unless a Toyota service bulletin specifies it, the wrong rating can push coolant out or overstress hoses and the radiator. Only open the cap when the engine is stone-cold, use a clean rag, and refill via the radiator neck (not just the reservoir) on variants with a radiator-mounted cap. Top up with Toyota Super Long Life Coolant (pink), bleed air with the heater on hot, and check for leaks after a short run under the bonnet.

Does the 2018 Vitz/Yaris actually have a radiator cap, and where is it?

Yes. Most 2018 Vitz/Yaris variants have the cap on the radiator neck, visible when the bonnet is open at the top front of the engine bay. Some market/engine combos may present a pressurised header tank with the cap on that tank—but either way, the system uses a pressure cap.

What pressure rating should the cap be?

Use a Toyota-spec cap around 1.1 bar (about 108 kPa), matching the Repair Manual test range of roughly 80–110 kPa. The rating is usually stamped on the cap. Sticking to the correct pressure helps prevent boil-over and avoids undue stress on hoses and the radiator.

When should the cap be replaced?

There’s no strict kilometre-only rule, but many techs replace at 4–5 years or 80,000–100,000 km, or any time it fails a pressure test or shows seal damage. Symptoms like intermittent overheating, overflow bottle filling and not returning, or collapsed hoses after cool-down point to a tired cap.