🔧 Legacy - Water Pump Replacement

On your Legacy, the water pump circulates coolant through the engine and radiator to prevent overheating. Replacing it typically involves draining the coolant and removing the front timing cover area to access the pump, then resealing everything correctly to prevent leaks.

Difficulty Level: Advanced | Estimated Time: 6-10 hours

Assumption: Stock FB25 engine layout (no modifications).

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⚠️ Safety & Precautions

• ⚠️ Never open the radiator cap on a hot engine; wait until fully cool.
• ⚠️ Disconnect the negative battery cable to prevent accidental starts.
• ⚠️ Support the car with jack stands; never rely on a floor jack alone.
• ⚠️ Coolant is toxic; keep away from kids/pets and clean spills immediately.
• ⚠️ Timing components must stay aligned; mark parts before removal.
• ⚠️ Use RTV sealant exactly as directed; improper sealing can cause major leaks.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• Drain pan (10-quart minimum)
• Spill-free coolant funnel kit
• Metric socket set (8mm-22mm)
• 10mm socket
• 12mm socket
• 14mm socket
• 22mm socket
• 3/8" drive ratchet
• 1/2" drive breaker bar
• Torque wrench (10-200 ft-lbs range)
• Torque wrench (inch-lb or low Nm range)
• Serpentine belt tool or long 14mm box wrench
• Crank pulley holding tool (specialty)
• Trim clip removal tool
• Flat plastic scraper
• Razor scraper
• Brake cleaner spray
• Shop towels
• Paint marker

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Water pump - Qty: 1
• Water pump O-ring / gasket (as equipped) - Qty: 1
• Timing cover RTV sealant (ThreeBond/Subaru-equivalent) - Qty: 1
• Engine coolant (Subaru-compatible pre-mix or 50/50 concentrate) - Qty: 2-3 gallons
• Accessory drive belt (serpentine belt) - Qty: 1
• Radiator drain plug gasket (if equipped/separate) - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and place wheel chocks at the rear wheels.
• Let the engine cool completely (radiator hoses should feel cool).
• Disconnect the battery negative terminal using a 10mm socket.
• Raise the front and support it on jack stands using a floor jack.
• Set the HVAC temperature to full HOT before refilling later (helps coolant flow through the heater core).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the lower splash shield

• Use a trim clip removal tool to pop out the plastic clips.
• Use a 10mm socket to remove any bolts, then remove the under cover.

Step 2: Drain the coolant

• Place a drain pan (10-quart minimum) under the radiator drain.
• Slowly remove the radiator cap (only if fully cool).
• Open the radiator drain using a 12mm socket (some drains are hand-turn; use only gentle force).
• Let coolant drain fully, then close the drain.
• Tip: Keep pets away from drained coolant.

Step 3: Remove the radiator fans (for access)

• Unplug fan electrical connectors by hand (press the tab, then pull).
• Use a 10mm socket to remove the fan mounting bolts.
• Lift the fan assemblies straight up and out carefully.

Step 4: Remove the accessory drive belt

• Place a 14mm socket on the belt tensioner.
• Rotate the tensioner to relieve belt tension, then slide the belt off.
• If you’re reusing the belt, note its routing or take a photo.

Step 5: Set the engine to Top Dead Center (TDC)

• Use a 22mm socket and 1/2" drive breaker bar on the crank bolt and rotate the engine clockwise.
• Align timing marks as you verify them during cover removal; use a paint marker to add your own marks.
• Tip: Never rotate backward to “catch” a mark.

Step 6: Remove the crank pulley

• Install the crank pulley holding tool (specialty) to keep the pulley from turning.
• Use a 22mm socket and 1/2" drive breaker bar to loosen and remove the crank bolt.
• Remove the pulley by hand (wiggle it straight off). If stuck, use gentle hand rocking only.
• Torque to 127 Nm (94 ft-lbs) for the crank bolt during reassembly.

Step 7: Remove front components blocking the timing cover

• Use a 10mm socket and 12mm socket to remove any brackets/covers that block the front timing cover.
• Keep bolts grouped by location (a simple “cardboard bolt map” helps).

Step 8: Remove the front timing cover

• Use a 10mm socket to remove the timing cover bolts.
• Carefully break the RTV seal and remove the cover using a flat plastic scraper.
• Do not gouge the sealing surface; switch to a razor scraper only for stubborn RTV.
• Tip: Scrape gently; aluminum scratches easily.

Step 9: Mark timing chain alignment before removing the pump

• Use a paint marker to mark the chain and the water pump sprocket alignment points.
• This is your “backup map” to ensure everything goes back exactly.

Step 10: Remove the water pump

• Place the drain pan under the pump area to catch remaining coolant.
• Use a 10mm socket to remove the water pump bolts.
• Remove the pump straight out. Expect some coolant to spill.
• Torque to 10 Nm (7 ft-lbs) for water pump bolts during reassembly.

Step 11: Clean mating surfaces

• Use a flat plastic scraper and shop towels to remove old gasket material/RTV.
• Use brake cleaner spray on a towel (not sprayed directly into the engine) to finish cleaning.
• Surfaces must be clean and dry before installing the new pump and resealing the cover.

Step 12: Install the new water pump

• Install the new water pump O-ring / gasket onto the pump (lightly wet with fresh coolant if it’s an O-ring style).
• Position the pump and start all bolts by hand.
• Tighten evenly in a crisscross pattern using a 10mm socket.
• Torque to 10 Nm (7 ft-lbs).

Step 13: Reseal and install the timing cover

• Apply a continuous bead of timing cover RTV sealant per the sealant instructions (consistent bead, no gaps).
• Install the cover carefully without smearing the bead excessively.
• Install bolts finger-tight first, then snug using a 10mm socket.
• Torque to 5 Nm (44 in-lbs) unless otherwise specified on your bolt grouping.
• Tip: Let RTV “skin” per tube directions.

Step 14: Reinstall the crank pulley and belt

• Install the crank pulley fully seated by hand.
• Use the crank pulley holding tool (specialty) and tighten the crank bolt with a torque wrench.
• Torque to 127 Nm (94 ft-lbs).
• Reinstall the serpentine belt using a 14mm socket on the tensioner.

Step 15: Reinstall radiator fans and splash shield

• Reinstall fans using a 10mm socket, then reconnect the electrical plugs.
• Reinstall the under cover using a 10mm socket and the trim clip removal tool.

Step 16: Refill and bleed the cooling system

• Install a spill-free coolant funnel kit on the radiator fill neck.
• Fill with the correct engine coolant until full.
• Reconnect the battery negative terminal using a 10mm socket.
• Start the engine and let it idle; keep the funnel installed and coolant level above the neck.
• As the thermostat opens, you’ll see bubbles; keep topping up until bubbles stop.
• Turn the cabin heat to HOT and confirm warm air from vents.

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✅ After Repair

• Check for leaks around the water pump area and timing cover with the engine idling.
• Let the engine reach normal temperature; confirm the radiator fans cycle on/off.
• Shut down, let it cool fully, then recheck coolant level in the radiator and overflow bottle and top off as needed.
• Test drive 10-15 minutes, then recheck for leaks again.
• Tip: A small level drop next day is normal.

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💰 DIY vs Shop Cost

Shop Cost: $900-$1,500 (parts + labor)

DIY Cost: $180-$350 (parts only)

You Save: $720-$1,150 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 6-10 hours.

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🎯 Ready to get started?

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