How to Replace a Subaru Water Pumpby Eli Laurens
Subaru engines have a radiator and water channel design that uses pumped and pressurized coolant to stabilize its internal temperature. Unlike most internal combustion engines, instead of a block and head, there are water jackets mounted around a main crankcase which cycle coolant through the engine. The primary water pump is mounted in a tight space on the front of the motor, and the average backyard mechanic can replace this pump in about two hours.
Drain the coolant from the system by disconnecting the lower radiator hose and allowing the fluid to collect in the drain pan. The hose has standard "pinch" hose clamps, and can be disengaged by gripping the clamp's arms together.
Remove the radiator by disconnecting the upper hose, fan shroud and fan, and the top bolts holding it in place. Once free, it will slide out towards the top of the motor.
Remove the drive belts and timing chain by releasing the tension on the tension pulley, then pulling them towards the front of the motor. The pump is in the very center of the engine, and has several bolts holding it in.
Remove the water pump by turning the five or six bolts in a counterclockwise direction. The pump will pull out towards the front of the car, and some residual coolant may spill out. Be sure to wipe the area clean, and remove the pump's gasket which may have stuck in the pump's mount location.
Replace the water pump by placing the rubber gasket into it, then positioning it to the motor and securing its bolts in a clockwise direction. The pump should make a firm seal against the motor, and the bolts should lock into place with authority.
Replace the timing chain and drive belts, radiator and fan/ fan shroud, and upper and lower hose connections to the radiator.
Fill the system with coolant by pouring coolant into the radiator, starting the car and continuing to pour until the system cannot take any more coolant. Cap the radiator and refill the overflow tank to the proper level.
- Use distilled water to increase protection from rust, debris and corrosion.
Things You'll Need
- Socket set
- Drain pan
- Collect and dispose of coolant properly.
Eli Laurens is a ninth-grade physics teacher as well as a computer programmer and writer. He studied electrical engineering and architecture at Southern Polytechnic University in Marietta, Ga., and now lives in Colorado.