🔧 Outback - Water Pump Replacement

Replacing the water pump on your Outback’s 3.6L flat-six requires draining the cooling system, removing the front accessory drive components, and installing a new pump with a fresh gasket. This is an involved repair because access is tight and the cooling system must be refilled and bled carefully to prevent overheating.

Difficulty Level: Advanced | Estimated Time: 4-6 hours

---

⚠️ Safety & Precautions

• ⚠️ Let the engine cool completely before opening the cooling system. Hot coolant can cause severe burns.
• ⚠️ Disconnect the negative battery cable before working near the radiator fans and accessory belt area.
• ⚠️ Support your Outback securely with jack stands if raising the front. Never rely on a jack alone.
• ⚠️ Keep coolant away from pets and children. It is toxic and tastes sweet.
• ⚠️ Do not mix coolant types. Use Subaru-compatible long-life coolant or equivalent phosphate-free coolant approved for aluminum engines.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 12mm socket
• 14mm socket
• 17mm socket
• 3/8-inch drive ratchet
• 1/2-inch drive ratchet
• 3/8-inch drive extension set
• 1/2-inch drive breaker bar
• Torque wrench inch-pound capable
• Torque wrench foot-pound capable
• Flat-blade screwdriver
• Phillips screwdriver
• Trim clip removal tool
• Serpentine belt tool or 14mm long-handle wrench
• Pliers
• Hose clamp pliers
• Plastic gasket scraper
• Drain pan 2-gallon minimum
• Coolant funnel kit spill-free style
• Floor jack rated 3-ton minimum
• Jack stands rated 3-ton minimum
• Wheel chocks
• Nitrile gloves
• Safety glasses

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Engine water pump - Qty: 1
• Water pump gasket - Qty: 1
• Subaru-compatible long-life engine coolant - Qty: 2 gallons
• Distilled water - Qty: 1 gallon if using concentrate
• Serpentine belt - Qty: 1
• Thermostat gasket or O-ring - Qty: 1 if thermostat housing is disturbed
• Radiator drain plug gasket - Qty: 1 if damaged or leaking

---

📋 Before You Begin

• Park your Outback on level ground, shift to Park, and set the parking brake.
• Place wheel chocks behind the rear wheels.
• Let the engine sit until it is fully cold.
• Use a 10mm socket to disconnect the negative battery cable. A battery cable is the large wire connected to the battery terminal.
• Open the hood and remove the radiator cap only when the engine is cold.
• If raising the front, use a floor jack at the front center jacking point and place jack stands under the front support points.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the Lower Splash Shield

• Put on safety glasses and gloves.
• Use a trim clip removal tool to remove the plastic clips from the lower engine splash shield.
• Use a 10mm socket to remove any lower shield bolts.
• Set the shield and clips aside in order. Take photos before removal.

Step 2: Drain the Cooling System

• Place a 2-gallon drain pan under the radiator drain area.
• Use pliers or your fingers to open the radiator drain plug slowly.
• Remove the radiator cap to help coolant drain faster.
• Let the coolant drain completely.
• Close the radiator drain plug by hand until snug. Do not overtighten plastic drain plugs.

Step 3: Remove the Air Intake Ducting

• Use a flat-blade screwdriver to loosen the intake hose clamp.
• Use a 10mm socket to remove the air intake duct fasteners as needed for working room.
• Move the ducting aside carefully without pulling hard on attached wiring or hoses.

Step 4: Remove the Serpentine Belt

• Draw or photograph the belt routing before removing it.
• Use a serpentine belt tool or 14mm long-handle wrench on the belt tensioner. The tensioner is a spring-loaded arm that keeps the belt tight.
• Rotate the tensioner to release belt tension.
• Slide the belt off the pulleys and remove it from the engine bay.
• Inspect the belt. If cracked, glazed, or oil-soaked, replace it.

Step 5: Remove Components Blocking the Water Pump

• Use a 10mm socket and 12mm socket to remove any brackets or covers blocking access to the front of the water pump.
• Use pliers or hose clamp pliers to move any spring hose clamps out of the way. A spring clamp is a metal clamp you squeeze to release hose pressure.
• Gently twist coolant hoses before pulling them off. Do not pry against plastic fittings.
• Keep bolts grouped by location. Cardboard makes a great bolt map.

Step 6: Remove the Water Pump Pulley if Equipped

• If pulley bolts are accessible, use a 10mm socket to loosen the pulley bolts before the pump is fully removed.
• If the pulley spins, hold it carefully with a gloved hand or strap-style holding method while loosening the bolts.
• Remove the pulley and set it aside.

Step 7: Remove the Water Pump

• Place the drain pan under the pump area because more coolant will spill.
• Use a 10mm socket and 12mm socket to remove the water pump mounting bolts.
• Note bolt lengths and positions. Some bolts may be different lengths.
• Gently tap the pump housing by hand or wiggle it loose. Do not gouge the engine sealing surface.
• Remove the old water pump and gasket.

Step 8: Clean the Sealing Surface

• Use a plastic gasket scraper to clean the engine-side sealing surface.
• Wipe the area clean with a lint-free rag.
• Do not use a metal scraper on aluminum surfaces. It can cause leaks.
• Make sure no old gasket material falls into the coolant passages.

Step 9: Install the New Water Pump

• Place the new water pump gasket onto the new pump.
• Position the new pump on the engine by hand.
• Start all bolts by hand first to avoid cross-threading. Cross-threading means the bolt is going in crooked and damaging threads.
• Use a 10mm socket or 12mm socket to snug the bolts evenly in a crisscross pattern.
• Use an inch-pound torque wrench to tighten the water pump bolts to Torque to 8-10 Nm (71-89 in-lbs) unless your included pump instructions specify otherwise.

Step 10: Reinstall Pulley, Hoses, and Brackets

• Use a 10mm socket to reinstall the water pump pulley if removed.
• Tighten pulley bolts evenly to Torque to 8-10 Nm (71-89 in-lbs).
• Use hose clamp pliers to reinstall coolant hose clamps in their original positions.
• Use a 10mm socket and 12mm socket to reinstall any removed brackets and covers.
• Tighten small bracket bolts to Torque to 18 Nm (13 ft-lbs) where applicable.

Step 11: Install the Serpentine Belt

• Route the belt around the pulleys using your photo or belt routing diagram.
• Use the serpentine belt tool or 14mm long-handle wrench to rotate the belt tensioner.
• Slip the belt over the final pulley, then slowly release the tensioner.
• Check that the belt ribs sit correctly in every grooved pulley.

Step 12: Reinstall Intake Ducting and Splash Shield

• Use a flat-blade screwdriver to tighten the air intake hose clamp.
• Use a 10mm socket to reinstall air duct fasteners.
• Use a trim clip removal tool and 10mm socket to reinstall the lower splash shield.

Step 13: Refill the Cooling System

• Install a spill-free coolant funnel kit on the radiator filler neck.
• Fill slowly with Subaru-compatible long-life coolant mixture until the funnel level stabilizes.
• Fill the coolant overflow reservoir to the “FULL” mark.
• Reconnect the negative battery cable using a 10mm socket.
• Tighten the battery terminal snugly. Do not overtighten.

Step 14: Bleed Air from the Cooling System

• Start the engine with the spill-free funnel still installed.
• Set the heater to full hot and blower to low. This helps coolant flow through the heater core.
• Let the engine idle and watch for air bubbles in the funnel.
• Squeeze the upper radiator hose gently with gloves to help move trapped air.
• When the radiator fans cycle on and off and bubbles stop, shut the engine off.
• Let the engine cool, then top off the radiator and reservoir as needed.

---

✅ After Repair

• Start your Outback and check around the water pump, hoses, and radiator drain for leaks.
• Watch the temperature gauge during the first test drive. Stop immediately if it rises above normal.
• After the engine cools completely, recheck the coolant level in the radiator and overflow reservoir.
• Recheck the serpentine belt alignment with a flashlight.
• Dispose of old coolant properly at a recycling or service facility. Do not pour it on the ground or into drains.

---

💰 DIY vs Shop Cost

Shop Cost: $650-$1,050 (parts + labor)

DIY Cost: $160-$350 (parts only)

You Save: $490-$700 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 4-6 hours.

---

🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.