Parts for your 2011 Honda Stream-Thermostat

2011 Honda Stream Thermostat — What it does and when to replace it

Based on technical references — the Honda Stream RN6–RN9 Service Manual (Cooling System section) and the Honda Electronic Parts Catalogue for the R18A 1.8L and R20A 2.0L engines — the 2011 Honda Stream is fitted with a conventional wax‑pellet engine coolant thermostat housed near the lower radiator hose outlet. It’s a standard, critical part of the cooling system on this model.

The thermostat’s job is simple but vital: help the Stream warm up quickly and then hold the engine in its sweet spot, usually opening around the high‑70s to low‑80s °C and fully open in the mid‑90s °C. That tight temperature control keeps fuel economy tidy, cabin heat reliable on cold mornings, and engine wear down. When it sticks shut, the Stream can overheat, when it sticks open, it’ll run cool, use more petrol, and take ages to get warm.

There’s no hard‑and‑fast replacement interval, but as good practice it’s worth considering a new thermostat when doing major cooling work — say every 150,000–200,000 km or 8–10 years — or any time there’s overheating, slow warm‑up, erratic temperature gauge behaviour, or brown/contaminated coolant. Always pair a replacement with fresh Honda‑approved long‑life coolant and a new O‑ring or gasket.

• Common signs it’s due: overheating under load, poor heater output, fluctuating temp gauge, or cooling fans running constantly.
• Best parts choice: quality OEM‑spec thermostat of the correct temperature rating, with the jiggle valve oriented at the top during install.
• Coolant: use the correct pre‑mix and bleed air properly with the heater on hot.

Handy replacement tips under the bonnet:

1. Let the engine cool fully, then drain coolant into a clean container.
2. Remove the intake ducting as needed for access, disconnect the lower radiator hose, and undo the thermostat housing bolts (tighten on refit to light factory spec, not “gorilla tight”).
3. Swap the thermostat and O‑ring, align the jiggle valve up, refit the housing, reconnect hoses, refill, and bleed the system. Check for leaks and verify stable operating temperature on a road test.

Treated as part of regular servicing, the thermostat helps the 2011 Honda Stream stay efficient, comfy, and dependable across Aussie and Kiwi conditions — from school runs to long holiday kilometres.

• What temperature does the 2011 Honda Stream thermostat open at?
  Most OEM‑spec units begin opening in the high‑70s to low‑80s °C and are fully open around the mid‑90s °C. That range balances quick warm‑up with stable operating temperature. Using the correct rating keeps fuel economy and performance on point.
• How often should the thermostat be replaced?
  There’s no fixed schedule. Replace it when symptoms show, any time the engine has overheated, or proactively during a major cooling service at roughly 150,000–200,000 km or 8–10 years. Always fit a new seal and fresh, correct coolant.
• Where is the thermostat on the 2011 Honda Stream?
  It sits in the thermostat housing at the engine end of the lower radiator hose. From above, it’s accessed near the front of the engine bay, removing the intake ducting often improves access on both R18A and R20A engines.