Parts for your 2016 Subaru Legacy-Thermostat

2016 Subaru Legacy Thermostat

Based on the Subaru Factory Service Manual for the 2015–2017 Legacy/Outback (Cooling section), Subaru Global Service Information (STIS), and genuine parts catalogues for the FB25 2.5i and EZ36 3.6R engines, the 2016 Subaru Legacy is fitted with a wax‑pellet engine coolant thermostat. It’s located at the water pump inlet in the lower radiator hose and specified to begin opening at approximately 82°C.

The thermostat on a 2016 Subaru Legacy quietly keeps the flat‑four or flat‑six right in its sweet spot. By staying shut when the engine’s cold, it helps the Legacy warm up quickly for better fuel economy, lower emissions, and a toasty heater under the bonnet of winter. Once it hits operating temperature, it meters coolant flow so the temperature stays steady in traffic, on the motorway, and up alpine passes.

As part of routine servicing, it’s smart to keep an eye on thermostat health. Typical signs it’s not happy include slow warm‑up or the gauge sitting low, weak cabin heat on the open road, overheating under load, coolant surging into the overflow bottle, or a check engine light with temperature‑related codes. If any of that pops up, or if the water pump is being replaced, a new thermostat and seal is cheap insurance.

• Always use an OEM‑spec thermostat and a fresh O‑ring/gasket.
• Install with the jiggle pin/air bleed at the 12 o’clock position to purge air.
• Refill with the correct Subaru Super Coolant (blue) premix or equivalent that meets the vehicle specification.
• Bleed the system with the heater on hot, idle the engine, squeeze the upper hose to burp air, and top up as needed.

There’s no strict replacement interval in the handbook, but many techs in Australia and New Zealand treat the thermostat as a preventative item every 8–10 years or 150,000–200,000 km, and whenever the cooling system is opened up. Check hoses, clamps, and the radiator cap at the same time, and tighten housing bolts to the factory torque spec rather than “as tight as the spanner allows”.

After replacement, a quick OBD scan shows the thermostat doing its job if coolant temperature settles near the mid‑90s°C once warm, the cabin heat is consistent, and the gauge stays rock‑steady on a summer arvo or a frosty morning alike.

Popular questions about the 2016 Subaru Legacy thermostat

What temperature does the thermostat open at?
From Subaru service information, the factory thermostat in the 2016 Legacy typically begins opening around 82°C and is fully open in the mid‑90s°C range. That balance gets the engine up to temp quickly and keeps it stable for efficient running and reliable cabin heat.

Where is the thermostat located?
On both the FB25 2.5i and the EZ36 3.6R, it sits in the housing at the water pump inlet on the lower radiator hose side. Access is from the front and underside of the engine bay