Parts for your 2013 Honda Stream-Thermostat housing

2013 Honda Stream thermostat housing — what it does and when to replace it

It’s absolutely relevant on this model. Technical references including the Honda Service Manual for RN6–RN9 (Cooling System section) and the Honda electronic parts catalog list a dedicated water outlet/thermostat housing assembly for the 2013 Honda Stream’s R18A/R20A engines. These documents show the thermostat mounted in a housing (often called the “water outlet”) on the cylinder head, with an O‑ring seal, hose connections, and provision for the engine coolant temperature sensor.

The thermostat housing on a 2013 Honda Stream anchors the thermostat, seals the coolant passage, and provides the outlet for coolant flow to the radiator. It keeps the engine right in that sweet spot for temperature, helping drivability, fuel economy, and heater performance. On high‑kilometre Streams, heat cycles and coolant chemistry can make the plastic housing brittle or the sealing face warp, leading to weeping leaks or temp swings. If the housing or its O‑ring is tired, coolant loss and overheating can follow fast.

As part of regular servicing, it’s smart to inspect the housing area for crusty residue, pink/blue staining, or a sweet coolant odour after a drive. Any dampness around the housing seam or hose necks is a red flag. When replacing the thermostat, budget for a new housing O‑ring as a minimum, many owners choose to swap the complete housing if it shows warping, cracking, or pitting.

• Typical symptoms: slow warm‑up or over‑cooling (often with a P0128 code), overheating in traffic, fluctuating gauge, visible leaks near the housing, or low coolant level with no obvious hose failure.
• Best practice on replacement: start with a stone‑cold engine, capture and recycle old coolant, clean mating surfaces, fit a fresh O‑ring, and tighten the housing bolts evenly to the service‑manual spec. Refill with Honda Type 2 (blue) premix and bleed air with the heater on HOT until the fans cycle twice.
• Good maintenance rhythm: inspect every service, change coolant about every 5 years/100,000 km (or per the book), and consider proactive housing replacement on older/original units showing any distortion.

DIYers will find access reasonable from above on the R18A, but tight hose clamps and sensor plugs can be fiddly. If there’s any doubt, a workshop can test for leaks and pressure‑check the cap. Given the cost of an overheat, a fresh thermostat, O‑ring, and, when needed, a new housing is cheap insurance for a Stream that runs cool under the harshest Aussie and Kiwi summers.

Popular questions about the 2013 Honda Stream thermostat housing

Where is the thermostat housing located on a 2013 Honda Stream?

It’s bolted to the cylinder head on the transmission side of the engine, where the upper radiator hose connects. On the R18A, look below the intake area, you’ll see the hose leading to a compact plastic/aluminium housing that holds the thermostat and seals with an O‑ring.

Access improves by removing the intake ducting and moving the hose aside. Always work from cold, as hot coolant is pressurised.

What are common failure signs of a Stream thermostat housing?

Seepage around the housing seam or hose neck, dried white/pink residue, temperature gauge hunting, slow cabin heat, or a Check Engine Light with a P0128 code are common tells. Long‑term heat can warp the housing or harden the O‑ring, causing leaks.

If there’s any cracking or distortion, replace the housing rather than just the thermostat.

Should the ECT sensor be replaced with the housing?

Not always, but it’s a convenient time. The housing often carries the engine coolant temperature sensor, and if the car has high kilometres or intermittent gauge readings, replacing the sensor and its seal alongside the thermostat and housing can prevent future dramas.

If the sensor is clean, accurate, and its connector is sound, it can be reused with a fresh seal.