Parts for your 2013 Honda Stream-Radiator cap

2013 Honda Stream radiator cap — what it does and when to replace it

Referencing Honda’s technical literature, the 2013 Honda Stream (RN6–RN9, R18A/R20A engines) is fitted with a conventional, pressurised radiator cap. The Honda Stream Service Manual cooling-system procedures call for removing the radiator cap during coolant filling and bleeding, and the Honda Electronic Parts Catalogue lists a 1.1 bar cap for these models (commonly referenced as Honda part 19045-PAA-A01 or equivalent). So, yes — the radiator cap is very much relevant on a 2013 Honda Stream.

The radiator cap’s job is bigger than it looks. It seals the cooling system and holds a set pressure (about 1.1 bar), raising the coolant’s boiling point so the engine can run efficiently without boiling over. It also manages coolant movement to and from the overflow bottle as things heat up and cool down, keeping the system topped up and free of air. If the cap’s spring weakens or the rubber seals harden, the Stream can run hotter, push coolant out, or pull air back in — all of which can lead to overheating, weak cabin heat, or random coolant loss.

For routine servicing of a 2013 Honda Stream, checking the radiator cap is a simple win. Under the bonnet, only remove the cap when the engine is stone cold. Look for cracks in the gasket, corrosion on the seat, or a sticky/saggy spring. If any of that shows up, replace it. Using the correct pressure rating matters — stick with a genuine Honda cap or a direct-spec 1.1 bar equivalent. A mismatched cap can cause overpressure leaks or early boiling.

Many owners time a new cap with a coolant change (typically every few years or specified kilometres). It’s inexpensive insurance against cooling-system headaches on longer Kiwi or Aussie road trips, towing weekends, and hot summer traffic.

1. Only open the radiator cap when cold — never when warm or hot.
2. Wipe the neck clean and inspect the sealing surface.
3. Fit the new 1.1 bar cap firmly until it positively locks.
4. After a drive cycle, check for stable coolant level in the overflow bottle.

If the Stream shows signs like frequent top-ups, sweet smells, or a hose that collapses as it cools, the cap is a prime suspect and an easy first fix before chasing bigger issues.

Popular questions about 2013 Honda Stream radiator caps

What pressure rating is the radiator cap on a 2013 Honda Stream?
Honda specifies a 1.1 bar (110 kPa) cap for RN6–RN9 Streams. Using the correct rating keeps the coolant from boiling early and protects hoses, radiator, and seals from overpressure.

How often should the radiator cap be replaced?
There’s no hard expiry, but many technicians replace the cap at each major coolant service or around 5 years/80–100,000 km. If the seal looks tired, the spring feels weak, or there are overheating/air-in-system symptoms, replace it sooner.

What are the signs of a failing radiator cap?
Common clues include random coolant loss, a collapsed upper hose after cool-down, overheating in traffic, or gurgling sounds after shut-down. Visible gasket cracking or crusty deposits on the cap seat are also tell-tales.