🔧 Legacy - Alternator Replacement

The alternator charges your battery and powers your A/C blower, lights, and engine electronics while the engine runs. Replacing it means disconnecting the battery, removing the drive belt, unbolting the alternator, then reinstalling and checking charging voltage.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.0 hours

---

⚠️ Safety & Precautions

• 🔋 Disconnect the battery negative terminal first to prevent a short.
• 🧤 Keep hands/tools away from the radiator fans; they can turn on unexpectedly.
• 🔥 Work on a cool engine to avoid burns from the exhaust and radiator hoses.
• 🧲 Don’t let the alternator B+ cable touch metal; it’s direct battery power.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 12mm socket
• 14mm socket
• 3/8" ratchet
• 3/8" torque wrench (10–80 ft-lbs range)
• 6" extension (3/8" drive)
• Flat-blade screwdriver
• Pliers
• Trim clip removal tool
• Serpentine belt tool or 14mm box wrench
• Multimeter
• Safety glasses
• Mechanic gloves
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Alternator - Qty: 1
• Serpentine drive belt - Qty: 1
• Battery terminal anti-corrosion washers or protectant - Qty: 1
• Dielectric grease - Qty: 1

---

📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Install wheel chocks behind the rear wheels.
• Open the hood and let the engine cool fully.
• Plan radio presets may reset when the battery is disconnected.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Disconnect the battery

• Use a 10mm socket to loosen the negative battery terminal clamp.
• Lift the negative cable off and tuck it aside so it can’t spring back.
• Negative off first, on last.

Step 2: Remove the intake duct (room to work)

• Use a flat-blade screwdriver to loosen the hose clamp(s) on the intake duct.
• Use pliers to release any spring clamps on small breather hoses.
• Remove any plastic clips using a trim clip removal tool, then lift the duct out.

Step 3: Release drive belt tension and remove the belt

• Locate the belt tensioner and use a serpentine belt tool or 14mm box wrench to rotate the tensioner and relieve tension.
• Slip the belt off the alternator pulley first, then release the tensioner slowly.
• Pull the belt out of the way and note the belt routing.
• Take a quick photo for routing.

Step 4: Disconnect alternator electrical connectors

• Unplug the alternator’s small connector by pressing the lock tab and pulling straight back (no yanking).
• Remove the rubber boot over the alternator power stud (B+).
• Use a 12mm socket to remove the B+ nut, then lift the cable off and move it aside.
• Apply a tiny amount of dielectric grease to the small connector seal on reassembly (not on the metal pins).

Step 5: Unbolt and remove the alternator

• Use a 14mm socket and 3/8" ratchet to remove the alternator mounting bolts.
• If a bolt is tight, use a 6" extension (3/8" drive) for better leverage and keep the socket fully seated.
• Lift the alternator out carefully without hitting the radiator or A/C lines.
• Torque on install: Torque alternator mounting bolts to Subaru factory specification (spec varies by mounting/bolt location).

Step 6: Install the new alternator

• Set the new alternator into place and start the mounting bolts by hand to avoid cross-threading.
• Tighten bolts evenly using a 14mm socket, then finish with a 3/8" torque wrench.
• Reconnect the B+ cable and nut using a 12mm socket, then reinstall the rubber boot.
• Reconnect the small electrical connector until it clicks.
• Torque on install: Torque B+ terminal nut to Subaru factory specification (do not over-tighten; the stud can break).

Step 7: Reinstall the belt

• Route the belt back on all pulleys except the alternator (easiest last).
• Use a serpentine belt tool or 14mm box wrench to rotate the tensioner again.
• Slip the belt onto the alternator pulley and slowly release the tensioner.
• Visually confirm the belt ribs are centered in every pulley groove.

Step 8: Reinstall the intake duct

• Reinstall the duct and hoses, then tighten clamps using a flat-blade screwdriver.
• Reinstall any clips using the trim clip removal tool as needed.

Step 9: Reconnect the battery

• Reinstall the negative battery cable and tighten using a 10mm socket.
• Install battery terminal anti-corrosion washers or protectant if you’re using them.

---

✅ After Repair

• Start the engine and confirm the battery/charging warning light stays off.
• Use a multimeter at the battery terminals: engine running should typically read about 13.8–14.7V.
• Turn on headlights + rear defrost + blower and verify voltage stays stable (not dropping into the low 12s).
• Listen for belt squeal and re-check belt alignment if you hear noise.
• If the battery light remains on, recheck the small alternator connector and the B+ nut/boot seating.

---

💰 DIY vs Shop Cost

Shop Cost: $550-$1,050 (parts + labor)

DIY Cost: $180-$450 (parts only)

You Save: $370-$600 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-2.5 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.