LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Subaru >> 2018 >> WRX Base >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 6 (Engine Cooling System (STI)) >> General Description >> Specification >> Notes
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Section 6 (Engine Cooling System (STI)): General Description: Specification: Notes

WARNING: This page is about a different variant/trim than selected.
ENGINE COOLING SYSTEM SPECIFICATION

Cooling System Electric Fan + Forced Engine Coolant Circulation System
Total Engine Coolant Capacity L (US qt, Imp qt) Approx. 7.7 (8.2, 6.8)
Water Pump Type Centrifugal impeller type
Discharge performance Discharge rate L (US gal, Imp gal)/min 200 (52.8, 44.0)
Pump speed - Discharge pressure 6, 000 r/min - 225.4 kPa (23.0 mAq)
Engine Coolant Temperature 80°C (176°F)
Impeller diameter mm (in) 76 (2.99)
Number of impeller vanes 8
Pump pulley diameter mm (in) 60 (2.36)
Clearance between impeller and pump case mm (in) Standard 0.5 - 1.5 (0.020 - 0.059)
Thermostat Type Wax pellet type
Starting temperature to open 76 - 80°C (169 - 176°F)
Fully opens 91°C (196°F)
Valve lift mm (in) 9.0 (0.354) or more
Valve opening size mm (in) 35 (1.38)
Radiator Fan Motor input Main fan W 160
Sub fan W 160
Fan diameter/Blade Main fan 320 mm (12.6 in)/9
Sub fan 320 mm (12.6 in)/11
Radiator Type Down flow
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 Coolant filler tank side 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 --4.9 (-0.01 --0.05, -0.1 --0.7)
Radiator side kPa (kg/cm2 , psi) Positive pressure side only Standard 122 - 152 (1.24 - 1.55, 18 - 22)
Limit 112 (1.14, 16)
Fins Corrugated fin type
Reservoir Tank Capacity L (US qt, Imp qt) 0.45 (0.48, 0.40)