Parts for your 2012 Subaru Xv-Thermostat housing

2012 Subaru XV thermostat housing — what it is, where it is, and how to look after it

Yes, the 2012 Subaru XV uses a thermostat housing. Technical sources including the Subaru Factory Service Manual for the GP-series XV/Impreza (Cooling section), Subaru’s FAST electronic parts catalogue (EPC), and mainstream workshop data (e.g., Haynes/Mitchell/Autodata) identify a separate water inlet/thermostat cover — commonly referred to as the thermostat housing — bolted to the water pump on the FB20 2.0‑litre boxer engine.

On this model, the thermostat housing does more than just cap the thermostat. It forms the alloy “water inlet” where the lower radiator hose connects, positively locates the thermostat against the water pump, and seals the joint with a rubber O‑ring or gasket. That neat little assembly controls coolant flow during warm‑up and then maintains stable operating temperature once the engine is up to temp — crucial for fuel economy, emissions, and long engine life.

For everyday servicing, it’s smart to give the housing a once‑over whenever coolant is changed or if there are cooling complaints. Look for pink/blue crust (dried coolant), dampness around the lower hose, or staining at the housing seam. If there’s weeping, the usual fix is a new thermostat and seal, replace the housing only if it’s warped, pitted, or cracked. Stick with quality parts — the genuine-spec alloy housing and the correct thermostat temperature rating keep the FB20 happy.

Replacement is straightforward for a competent DIYer, though many owners prefer a workshop. The typical steps are:

1. Cool the engine fully, then drain enough coolant to drop the level below the thermostat.
2. Remove the lower radiator hose and unbolt the housing from the water pump.
3. Clean mating faces, fit a new thermostat and O‑ring, and refit the housing.
4. Torque the bolts to factory spec, reconnect the hose, refill with the correct Subaru‑approved coolant mix, and bleed air thoroughly.

Bleeding on a boxer is worth doing patiently: heater on hot, revs held briefly at 2,000–2,500 rpm, squeeze the upper and lower hoses to burp bubbles, and wait for the fans to cycle. Top up the radiator and overflow bottle, then re‑check levels over the next couple of drives (say, 50–100 kilometres). If overheating, slow warm‑up, or repeat leaks persist, book it in — there may be a sticky thermostat, a tired cap, or another cooling system issue under the bonnet.

Popular questions about the 2012 Subaru XV thermostat housing

Where is the thermostat housing on a 2012 Subaru XV?
It sits low on the front of the engine, at the water pump inlet where the lower radiator hose connects. From under the front bumper or with the engine undershield removed, you can see the alloy elbow secured to the pump with a couple of bolts.

Do I need to replace the housing when changing the thermostat?
Not usually. Most services replace the thermostat and O‑ring only. Replace the housing if it’s corroded, cracked, or the sealing face is damaged. If the lower hose nipple is pitted or the bolt threads are suspect, a new housing is cheap insurance.

How long does the job take?
A workshop typically allows about an hour or two, including proper coolant bleeding. DIY time varies with tools and experience, the fiddly bit is bleeding the cooling system thoroughly so there’s no trapped air.