🔧 RX350 - Water Pump Replacement

Your water pump circulates coolant through the engine and radiator. When it leaks (often from the pump “weep hole”) or the bearing wears out, you can lose coolant and overheat, so replacement is important.

Difficulty Level: Advanced | Estimated Time: 3-5 hours

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⚠️ Safety & Precautions

• ⚠️ Let the engine cool completely before opening the cooling system.
• ⚠️ Coolant is toxic; keep it away from kids and pets, and clean spills.
• ⚠️ Support the vehicle with jack stands; never rely on a floor jack.
• ⚠️ Keep hands clear of the cooling fans; they can turn on unexpectedly.
• ⚠️ If you’ll be working near the radiator fan wiring, disconnect the negative battery terminal.

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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
• Safety glasses
• Nitrile gloves
• Drain pan (at least 10-quart)
• Funnel
• Spill-free coolant funnel kit (specialty)
• Trim clip remover
• Flathead screwdriver
• 10mm socket
• 12mm socket
• 14mm socket
• 3/8" ratchet
• 3/8" torque wrench (10–100 Nm range)
• Serpentine belt tool (specialty)
• Breaker bar (3/8" or 1/2" drive)
• Pliers (hose clamp)
• Plastic gasket scraper
• Shop rags

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Water pump assembly - Qty: 1
• Water pump gasket/O-ring (if not included) - Qty: 1
• Serpentine drive belt - Qty: 1
• Toyota/Lexus Super Long Life Coolant (pink, premixed 50/50) - Qty: 2-3 gallons
• New hose clamps (optional, if originals are weak) - Qty: 2-4

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📋 Before You Begin

• Park on level ground, set the parking brake, and chock the rear wheels.
• Let the engine cool for at least 2-3 hours (overnight is best).
• Raise the front of your RX350 using a floor jack and support it with jack stands.
• If you choose to disconnect the battery, use a 10mm socket to remove the negative terminal and isolate it so it can’t spring back.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the lower splash shield

• Use a floor jack (rated 3-ton minimum) and jack stands (rated 3-ton minimum) to safely support the front end.
• Use a trim clip remover and 10mm socket to remove the lower engine cover/splash shield fasteners.
• Set the shield and clips aside in a tray so you don’t lose them.

Step 2: Drain the coolant

• Place a drain pan (at least 10-quart) under the radiator drain.
• Use a flathead screwdriver to open the radiator drain cock (turn slowly).
• Remove the radiator cap only after you confirm the system is cool (no pressure release sound).
• Tip: Save old coolant only if clean.

Step 3: Remove the drive belt

• Locate the belt routing and take a photo for reference.
• Use a serpentine belt tool (specialty) or breaker bar (3/8" or 1/2" drive) on the belt tensioner to relieve tension.
• Slide the belt off one pulley, then remove it from the rest.

Step 4: Disconnect hoses at the water pump area

• Use pliers (hose clamp) to slide spring clamps back on the hose(s) you need to move.
• Twist the hose gently by hand to break it free, then pull it off.
• Have shop rags ready for coolant drips.

Step 5: Remove the water pump pulley (if equipped)

• If your pump uses a separate pulley, use a 10mm socket or 12mm socket (as applicable) to remove the pulley bolts.
• Hold the pulley by hand while loosening bolts; if it slips, reinstall the belt briefly to hold it while you crack the bolts loose.

Step 6: Remove the water pump

• Use a 10mm socket and 12mm socket to remove the water pump mounting bolts (there may be multiple lengths).
• Keep bolts organized in a pattern on cardboard so they go back in the same locations.
• Carefully pry the pump loose by hand; do not gouge the aluminum mating surface.

Step 7: Clean the sealing surface

• Use a plastic gasket scraper to clean the engine mating surface.
• Wipe clean with shop rags until dry and smooth.
• Tip: Do not use a metal scraper.

Step 8: Install the new water pump

• Install the new gasket/O-ring onto the new pump (if it’s an O-ring, make sure it’s fully seated).
• Position the pump and hand-start all bolts to prevent cross-threading.
• Use a 3/8" torque wrench (10–100 Nm range) to tighten evenly in a crisscross pattern: Torque to 10 Nm (89 in-lbs).

Step 9: Reinstall the water pump pulley (if equipped)

• Install the pulley and start all bolts by hand.
• Use a 3/8" torque wrench (10–100 Nm range) with the correct socket to tighten: Torque to 21 Nm (15 ft-lbs).

Step 10: Reconnect hoses

• Slide hoses fully onto their fittings.
• Use pliers (hose clamp) to return clamps to their original positions.
• Double-check every clamp is centered over the fitting bead.

Step 11: Install the new drive belt

• Route the belt according to your photo (ribbed side on ribbed pulleys).
• Use a serpentine belt tool (specialty) to rotate the tensioner and slip the belt on the last pulley.
• Visually confirm the belt is seated in every pulley groove.

Step 12: Refill and bleed the cooling system

• Close the radiator drain cock using a flathead screwdriver (snug only).
• Fill the radiator with Toyota/Lexus Super Long Life Coolant (pink, premixed 50/50) using a funnel or spill-free coolant funnel kit (specialty).
• Fill the coolant reservoir to the “FULL” line.
• Start the engine and set the heater to max heat and fan medium.
• Let it idle and watch for air bubbles; add coolant as the level drops.
• Once warm, gently rev to ~2000 rpm a few times and monitor temperature.
• When bubbles stop and heat is steady, shut off, let cool, then top off radiator and reservoir.

Step 13: Reinstall the splash shield

• Use a 10mm socket and trim clip remover to reinstall the lower splash shield.
• Lower the vehicle safely using the floor jack (rated 3-ton minimum).

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✅ After Repair

• Start the engine and check for leaks around the water pump and hose connections.
• Verify the heater blows hot and the temperature gauge stays normal.
• After your first drive, let it cool and recheck the reservoir level; top off if needed.
• Look under the vehicle the next morning for any dried pink coolant residue.

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💰 DIY vs Shop Cost

Shop Cost: $800-$1400 (parts + labor)

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

You Save: $350-$1200 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 3-5 hours.

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🎯 Ready to get started?

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