How to Replace the Serpentine Belt on a 2020 Subaru Outback (Step-by-Step Guide)
Tools, belt routing tips, tensioner release steps, safety precautions, and post-install checks for 2020, 2021, 2022, 2023, 2024
How to Replace the Serpentine Belt on a 2020 Subaru Outback (Step-by-Step Guide)
Tools, belt routing tips, tensioner release steps, safety precautions, and post-install checks for 2020, 2021, 2022, 2023, 2024
🔧 Outback - Serpentine Belt Replacement
The serpentine belt (the single belt that drives the alternator and A/C) can wear, crack, or start squealing. On your Outback, replacement is usually straightforward because the belt is held tight by an automatic belt tensioner (a spring-loaded pulley that keeps the belt tight).
Difficulty Level: Intermediate | Estimated Time: 0.5-1.0 hours
⚠️ Safety & Precautions
- 🧯 Work on a cool engine; hot pulleys can burn you.
- 🧤 Keep fingers/tools clear of pulleys; the tensioner can snap back.
- 🧱 If you raise the front, support with jack stands; never rely on a jack.
- 🔋 Battery disconnect is not required, but keep the key far away and do not start the engine during the job.
🔧 Required Tools
You'll need the following tools for this repair:
- 14mm socket
- 17mm socket
- 3/8" ratchet
- 3/8" breaker bar (18"-24")
- 10mm socket
- Trim clip removal tool
- Flashlight
- Floor jack (rated 3-ton minimum)
- Jack stands (rated 3-ton minimum)
- Wheel chocks
- Mechanic gloves
- Safety glasses
🔩 Required Parts
HowToo sells all the parts you need for this repair:
- Serpentine belt - Qty: 1
📋 Before You Begin
- Park on level ground, shift to Park, and set the parking brake.
- Chock a rear wheel using wheel chocks.
- Open the hood and locate the belt routing diagram (usually on a sticker under the hood). If it’s missing, take a clear photo of the current belt routing before removing it.
- If access is tight from above, raise the front slightly with a floor jack (rated 3-ton minimum) and support with jack stands (rated 3-ton minimum).
🔨 Step-by-Step Instructions
Follow these steps in order:
Step 1: Confirm belt routing and inspect pulleys
- Use a flashlight to find the belt routing diagram and compare it to what you see.
- Check the belt for cracks, missing ribs, or glazing (shiny, hardened rubber).
Step 2: Remove any covers that block access (if equipped)
- If your Outback has a plastic engine cover, remove it by pulling up firmly by hand (it’s held by rubber grommets).
- If you’re working from underneath and there’s a lower splash shield in the way, remove fasteners with a 10mm socket and a trim clip removal tool.
Step 3: Locate the automatic belt tensioner
- Use a flashlight to locate the tensioner pulley (the pulley on a spring-loaded arm).
- Find the bolt head on the tensioner pulley/arm that your tool will turn.
Step 4: Relieve belt tension
- Install a 14mm socket on a 3/8" breaker bar (18"-24") and test-fit it on the tensioner’s bolt head.
- If 14mm does not fit snugly, switch to a 17mm socket on the same breaker bar.
- Rotate the tensioner smoothly to relieve tension. Hold steady; don’t let it snap back.
Step 5: Remove the old belt
- While holding the tensioner rotated with the breaker bar, slip the belt off the easiest-to-reach pulley (often the top pulley).
- Slowly release the tensioner back to its resting position.
- Remove the belt from the remaining pulleys and pull it out.
Step 6: Install the new belt (start routing first, tension last)
- Route the new belt around the pulleys following the under-hood belt routing diagram.
- Make sure the belt ribs sit fully in the grooved pulleys (no ribs hanging off).
- Leave the easiest pulley for last so you can slip the belt on while the tensioner is rotated.
Step 7: Apply tension and seat the belt
- Rotate the tensioner again using the breaker bar and the correct socket.
- Slip the belt onto the last pulley, then slowly release the tensioner.
- Use the flashlight to re-check every pulley: the belt must be centered and fully seated.
Step 8: Reinstall covers/shields
- Reinstall any splash shield fasteners using the 10mm socket and trim clip removal tool.
- Reinstall the engine cover by aligning grommets and pressing down by hand.
✅ After Repair
- Start the engine and watch the belt for 15–30 seconds. It should run straight with no wobble.
- Listen for squeal or chirping. If you hear noise, shut it off and re-check belt seating on every pulley.
- After a short 5–10 minute drive, re-check belt alignment again with a flashlight.
💰 DIY vs Shop Cost
Shop Cost: $180-$350 (parts + labor)
DIY Cost: $25-$70 (parts only)
You Save: $110-$325 by doing it yourself!
Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.0 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.









