Parts for your 2005 Daihatsu Yrv-Radiator cap

2005 Daihatsu YRV radiator cap — what it does and how to look after it

The 2005 Daihatsu YRV does use a radiator cap. Daihatsu’s YRV (M200/M201/M211) Workshop Manual – Cooling System section specifies a pressure-type radiator cap fitted to the radiator neck (nominally around 0.9 bar), with inspection and testing procedures. The Daihatsu Electronic Parts Catalogue for the M2# series lists the radiator cap as a distinct service part, and AU/NZ aftermarket catalogues (e.g., Tridon and Dayco) also list a direct-fit 0.9 bar cap for the 2005 YRV. So, the radiator cap is absolutely relevant on this model.

On this YRV, the radiator cap does more than just seal the top of the radiator. It holds pressure in the cooling system so the coolant’s boiling point is raised, helping the engine keep its cool on hot days, steep climbs and at motorway speeds. Inside the cap are pressure and vacuum valves: when coolant heats up and expands, excess pressure vents to the overflow bottle, as it cools and contracts, the cap draws coolant back in so the system stays full and air-free.

Because the cap is a little mechanical valve, it wears. A tired cap can cause sneaky overheating, coolant loss, or hoses that collapse as the engine cools. It’s a smart move to:

• Check the cap at each service (or at least yearly) using a pressure tester if available.
• Replace it every 3–5 years, or whenever the rubber seals harden, crack, or the spring test is out of spec.
• Stick with the correct rating (around 0.9 bar/13 psi for most YRV variants, including turbo K3-VET). If unsure, read the old cap’s stamp or the workshop manual.

Always open the cap only when the engine is stone cold. With the bonnet up, wipe dust away, then press down and twist the cap off. Inspect the sealing surfaces on the radiator neck, clean gently if there’s scale. Fit the new cap squarely and twist until fully seated. Top up the radiator itself (not just the bottle) with the right premix coolant, then set the overflow bottle to the “COLD” mark. After a decent drive, recheck levels.

Clues the cap may be crook:

• Coolant stains around the filler neck or overflow hose
• Overheating at speed but fine at idle
• Hoses that go rock-hard when hot or collapse when cooling
• Coolant pushed into the bottle and not drawn back on cooldown

A quality, correctly rated cap is cheap insurance for the YRV’s cooling system and turbo health (if fitted), helping keep temps steady and the heater working properly.

Popular questions

What pressure radiator cap does a 2005 Daihatsu YRV use?
Most 2005 YRV variants run a 0.9 bar (around 13 psi) cap. That’s what Daihatsu specifies in the YRV cooling system specs and what AU/NZ parts catalogues list. If the car’s had cooling mods or a replacement radiator, verify the rating stamped on the current cap or check the workshop manual for the exact engine code.

Where is the radiator cap on a 2005 YRV?
It’s on the radiator itself, at the filler neck on the top tank. Pop the bonnet and look towards the top of the radiator, on many YRVs it’s near the upper hose side. The plastic overflow bottle beside the radiator is not pressurised — the metal spring-loaded cap on the radiator is the one that controls system pressure.

How often should the radiator cap be replaced?
Have it tested at each service or at least once a year, and replace it every 3–5 years or whenever it fails a pressure test or shows perished seals. If you’re doing a coolant change, thermostat, radiator, or water pump, it’s sensible to fit a fresh, correct-rating cap at the same time.