Parts for your 1999 Toyota Echo|yaris-Radiator cap

1999 Toyota Echo/Yaris radiator cap — purpose, fitment, and easy servicing tips

Yes, the 1999 Toyota Echo/Yaris uses a radiator cap. Technical sources confirm it’s a pressurised cooling system with a dedicated cap: the Toyota Vitz/Yaris repair manual for SCP10/NCP10/NCP13 outlines a “Radiator Cap Sub-Assembly” with a cap valve opening pressure of roughly 78–108 kPa (about 0.8–1.1 bar), while Toyota’s Electronic Parts Catalogue lists a radiator cap sub-assembly for these models (common part numbers seen include 16401-20353 and 16401-31650). Major aftermarket catalogues also specify a 13 psi (0.9 bar) cap for the 1999 Echo/Yaris. That all points to a normal, serviceable radiator cap being fitted from factory.

On this model, the radiator cap does more than just seal the top. It sets system pressure so the coolant can run hotter without boiling, helps purge air, and allows expansion and recovery of coolant through the overflow hose and bottle. When the cap’s spring and seals are healthy, the Echo/Yaris runs at the right temperature, the heater works properly, and coolant stays where it should.

As part of routine servicing of a 1999 Toyota Echo/Yaris, it’s smart to give the radiator cap a quick once‑over. Look for perished rubber seals, a sticky or weak spring, crusty deposits on the seat, or a distorted filler neck. If there are signs of age or overheating history, a fresh cap is cheap insurance.

• Pressure rating: typically 0.9 bar (13 psi). Stick to the rating stamped on the original cap or the spec in the service manual.
• Inspection (engine cold only): check the rubber seal for cracks, ensure the spring moves smoothly, and confirm the overflow hose is tight and clear.
• Replacement interval: many techs replace the cap whenever coolant is renewed, or at 5 years/100,000 km, whichever comes first. Replace immediately if the cap fails a pressure test.
• Testing: a cooling-system pressure tester with a cap adapter can confirm the opening pressure and holding ability sit within the 78–108 kPa range noted in the manual.
• Coolant top-up: only remove the cap when stone cold. Refill with Toyota‑approved coolant mix, bleed air as specified, and verify the overflow bottle level after a drive.

Depending on market and exact variant, the cap is usually on the radiator’s top tank, some have a remote filler neck near the engine. Either way, clean the seat, fit the new cap squarely, and twist to the full lock so the seal engages properly.

What pressure radiator cap does a 1999 Toyota Echo/Yaris use?

Most run a 0.9 bar (13 psi) cap. Toyota’s workshop specs allow roughly 78–108 kPa for cap opening pressure. Best bet is to match the rating stamped on the original or follow the service manual for the specific engine code.

How often should the radiator cap be replaced on a 1999 Echo/Yaris?

If it passes a pressure test and seals cleanly, it can stay in service. Many mechanics replace it preventatively with each major coolant change, or around 5 years/100,000 km. Replace immediately if there’s coolant loss, hose collapse after cool-down, or visible seal damage.

Where is the radiator cap located on this model?

Typically on the top of the radiator, near the upper support panel. Some variants have a remote filler neck near the engine with the overflow hose attached. If in doubt, follow the top radiator hose to the highest fill point with a twist-lock cap.