Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2021 Subaru WRX STIFACTORY OEM SERVICE PROCEDURE
Section 12 (Engine Cooling System (2.0L)): General Description: Specification
WARNING: This page is about a different variant/trim than selected.
| Cooling system | Electric fan + Forced engine coolant circulation system | |||
| Total engine coolant capacity L (US qt, Imp qt) | CVT model: Approx. 8.3 (8.8, 7.3) | |||
| MT model: Approx. 8.1 (8.6, 7.2) | ||||
| Water pump | Type | Centrifugal impeller type | ||
| Discharge performance | Discharge rate L (US gal, Imp gal)/min | 248 (65.5, 54.6) | ||
| Pump speed - Discharge pressure | 8, 580 r/min - 88 kPa (8.9 mAq) | |||
| Engine coolant temperature | 80°C (176°F) | |||
| Impeller diameter mm (in) | 56 (2.2) | |||
| Number of impeller vanes | 7 | |||
| Pump pulley diameter mm (in) | 100 (3.9) | |||
| Thermostat | Type | Wax pellet type | ||
| Starting temperature to open | 86 - 90°C (187 - 194°F) | |||
| Fully opens | 95°C (203°F) | |||
| Valve lift mm (in) | 8.0 (0.315) or more | |||
| Valve opening size mm (in) | 32 (1.26) | |||
| Radiator fan | Motor input | Main fan W | 120 | |
| Sub fan W | 120 | |||
| Fan diameter/Blade | Main fan | 320 mm (12.6 in)/9 | ||
| Sub fan | 320 mm (12.6 in)/11 | |||
| Radiator | Type | Down flow, pressure type | ||
| Core dimensions | Width x Height x Thickness mm (in) | 687.4 x 340 x 16 (27.06 x 13.39 x 0.63) | ||
| Pressure range in which cap valve is open kPa (kg/cm2 , psi) | Positive pressure side | Standard | 93 - 123 (0.95 - 1.25, 14 - 18) | |
| Limit | 83 (0.85, 12) | |||
| Negative pressure side | Standard | -1.0 to -4.9 or less (-0.01 --0.05, -0.1 --0.7) | ||
| Fins | Corrugated fin type | |||
| Reservoir tank | Capacity L (US qt, Imp qt) | 0.45 (0.48, 0.40) | ||
| Recommended materials | Item number | Alternative | |
|---|---|---|---|
| Engine coolant | SUBARU SUPER COOLANT (concentrated type) | - | - |
| SUBARU SUPER COOLANT (diluted type) | K0670Y0001 | ||
| Water for dilution | Distilled water | - | Soft water or tap water |
| Cooling system protective agent | Cooling system conditioner | SOA345001 | - |
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.