Parts for your 2018 Toyota C-hr-Radiator cap

2018 Toyota C‑HR radiator cap — what’s actually fitted?

According to Toyota’s technical literature for the 2018 C‑HR — including the Owner’s Manual cooling-system guidance, the Repair Manual cooling-system diagrams for the 8NR‑FTS/2ZR‑FXE engines, and Toyota’s Electronic Parts Catalogue — there isn’t a traditional radiator-cap on the radiator itself. The radiator is a sealed unit with no filler neck. The pressure cap lives on the pressurised coolant reservoir (expansion tank), which is the system’s high point under the bonnet. So a “radiator-cap” as a separate part on top of the radiator isn’t used on this model, the service-relevant cap is the reservoir’s pressure cap.

Why did Toyota do it this way? Modern cooling systems on compact crossovers like the C‑HR use a remote, pressurised expansion tank to make the system easier to fill and bleed, reduce leak points, and improve packaging under the bonnet. By deleting the radiator filler neck and moving the pressure cap to the reservoir, Toyota can keep the cap at the highest point for better air purging, run a lower bonnet line, and simplify service — technicians add coolant at the reservoir, not the radiator. Toyota documentation also specifies the cap’s pressure rating (commonly around 108 kPa/1.1 bar for this platform) on the reservoir cap, while the radiator sub‑assembly is listed without any cap.

What should an owner or technician keep in mind? Treat the reservoir cap as the critical pressure cap for the whole cooling system:

• Only remove the reservoir cap when the engine is stone cold — it’s a pressurised system.
• Inspect the cap’s rubber seals and spring for hardening, cracks, or corrosion. Replace the cap if there’s any doubt, or if there are signs of coolant pushing into the overflow or hoses going soft/collapsing after cool‑down.
• Use a genuine or equivalent cap with the correct pressure rating printed on the cap (about 108 kPa/1.1 bar for the C‑HR), the wrong rating can cause overheating or premature hose/radiator stress.
• If overheating, coolant loss, or heater performance issues crop up, a workshop can pressure‑test the cap and cooling system as part of diagnosis.

These points align with Toyota’s service information: the “cap” that matters on a 2018 C‑HR is on the expansion tank, not on the radiator. It’s a small part that does a big job, keeping the coolant at the right pressure so the engine runs happily through hot Aussie and Kiwi summers.

• Where is the radiator cap on a 2018 Toyota C‑HR?
  The C‑HR doesn’t have a cap on the radiator itself. The pressure cap is on the pressurised coolant reservoir (expansion tank) under the bonnet. Only open it when the engine is completely cool.
• What pressure rating should the C‑HR’s cap have?
  Toyota specifies roughly 108 kPa (1.1 bar) for this platform. Check the marking on the existing cap and match it with a genuine Toyota cap or an equivalent quality cap with the same rating.
• When should the cap be replaced?
  Replace it if the seals are brittle or cracked, the spring feels weak, there’s evidence of coolant escaping past the cap, or as a preventive step when doing a coolant change. A workshop can pressure‑test the cap if you’re unsure.