🔧 GS350 - Serpentine Belt Replacement

The serpentine belt (also called the drive belt) spins your alternator and A/C compressor. On your GS350, you release the automatic belt tensioner, slip the old belt off, then route and seat the new belt correctly on every pulley.

Difficulty Level: Intermediate | Estimated Time: 1.0-2.0 hours

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⚠️ Safety & Precautions

• 🧤 Work on a cool engine; belts and pulleys can burn you.
• 🧯 Keep fingers, hair, and clothing away from pulleys at all times.
• 🧰 Support the car with jack stands if you raise it; never rely on a floor jack alone.
• 🔌 Battery disconnect is not required, but keep the key away from the car so nobody can start it while your hands are near the belt.

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🔧 Required Tools

You'll need the following tools for this repair:

• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• 21mm socket
• 1/2" drive breaker bar
• 1/2" drive ratchet
• Socket set 10mm-19mm
• Serpentine belt tool (specialty)
• Trim clip removal tool
• Flathead screwdriver
• Flashlight
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Serpentine belt - Qty: 1

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📋 Before You Begin

• 🅿️ Park on level ground, set the parking brake, and chock the rear wheels.
• 🔦 Take a clear photo of the belt routing before removal (or sketch it).
• 🧼 If you see oil/coolant on the belt area, fix the leak first; fluids quickly ruin a new belt.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove top-side covers for access

• Open the hood and remove the plastic engine cover (it pulls up on most Lexus covers; if yours has fasteners, use a 10mm socket).
• Use a flashlight to locate the serpentine belt at the front of the engine.

Step 2: Raise the right-front corner (if needed for access)

• Place wheel chocks behind the rear wheels.
• Lift the right-front jack point using a floor jack (rated 3-ton minimum).
• Set the vehicle securely on jack stands (rated 3-ton minimum).
• Remove the right-front wheel using a 21mm socket and 1/2" drive breaker bar.

Step 3: Remove the right-front inner splash shield (if equipped)

• Remove plastic clips using a trim clip removal tool.
• Remove any screws using a flathead screwdriver (or a 10mm socket if bolts are used).
• Pull the liner back enough to clearly see the belt and pulleys.

Step 4: Find the automatic belt tensioner and set up your tool

• Locate the belt tensioner (a spring-loaded arm with a pulley). The “hex” to rotate it is typically on the tensioner arm or at the pulley bolt area.
• Use a serpentine belt tool (specialty) for tight access, or use a 1/2" drive ratchet with the correct socket from your socket set 10mm-19mm.
• Use the socket that fits snugly.

Step 5: Release belt tension

• Rotate the tensioner using the serpentine belt tool (specialty) or 1/2" drive ratchet to relieve tension (you’ll feel the spring resistance).
• While holding the tensioner rotated, slide the belt off the easiest-to-reach smooth pulley using your free hand.
• Slowly let the tensioner return to its rest position (don’t let it snap back).

Step 6: Remove the old belt and inspect pulleys

• Pull the belt out of the engine bay from the top or through the wheel-well opening.
• Spin each pulley by hand (idler, tensioner pulley, alternator, A/C). They should spin smoothly and quietly.
• If a pulley wobbles, feels rough, or squeals, that component should be replaced before installing the new belt.

Step 7: Route the new belt

• Route the new belt to match your photo/sketch. Make sure the ribbed side seats into the grooves of ribbed pulleys.
• Leave the easiest-to-reach pulley for last (usually a smooth idler/tensioner pulley).
• Use a flashlight to confirm the belt is centered on every pulley.

Step 8: Re-apply tension and seat the belt

• Rotate the tensioner again using the serpentine belt tool (specialty) or 1/2" drive ratchet.
• Slip the belt fully onto the last pulley.
• Slowly release the tensioner back onto the belt.
• Re-check every pulley: the belt ribs must be fully in the grooves and not hanging off an edge.

Step 9: Reinstall splash shield and wheel (if removed)

• Reinstall the liner using the trim clip removal tool (to seat clips) and flathead screwdriver or 10mm socket for fasteners.
• Reinstall the wheel using a 21mm socket.
• Lower the vehicle using the floor jack (rated 3-ton minimum) and remove the jack stands (rated 3-ton minimum).

Step 10: Reinstall engine cover

• Reinstall the engine cover (press into place or use a 10mm socket if fasteners are used).

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✅ After Repair

• 🧪 Start the engine and watch the belt for 20–30 seconds. It should run smoothly with no wandering.
• 🔊 Listen for chirping/squealing. If you hear noise, shut it off and re-check belt alignment on every pulley.
• 🕵️ After a short test drive, re-check the belt seating again with a flashlight.

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💰 DIY vs Shop Cost

Shop Cost: $180-$350 (parts + labor)

DIY Cost: $35-$80 (parts only)

You Save: $145-$270 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-2.0 hours.

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🎯 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.