🔧 Prius - Radiator Hose Replacement

On your Prius, a radiator hose carries engine coolant between the radiator and engine. Replacing a leaking hose is straightforward, but you must drain/contain coolant and bleed air out afterward so the engine doesn’t overheat.

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

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⚠️ Safety & Precautions

• ⚠️ Only work on a fully cold engine; hot coolant can cause severe burns.
• ⚠️ Support the car with jack stands; never rely on a jack alone.
• ⚠️ Keep hands/tools away from orange high-voltage cables and hybrid components.
• ⚠️ Coolant is toxic; keep away from kids/pets and clean spills immediately.
• ⚠️ Do not mix coolant types; use Toyota pink coolant only.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Floor jack (rated 2-ton minimum)
• Jack stands (rated 2-ton minimum)
• Wheel chocks
• 10mm socket
• 1/4" ratchet
• Torque wrench (in-lb or low Nm)
• Trim clip removal tool
• Hose clamp pliers (specialty)
• Channel-lock pliers
• Pick tool
• Drain pan (at least 2 gallons)
• Spill-free funnel kit (specialty)
• Shop towels
• Flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Upper radiator hose - Qty: 1
• Lower radiator hose - Qty: 1
• Radiator hose clamps - Qty: 2
• Toyota Super Long Life Coolant (pink, pre-mixed 50/50) - Qty: 1-2 gallons

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📋 Before You Begin

• Park on level ground, set the parking brake, and chock the rear wheels.
• Let the engine cool completely (overnight is best).
• Confirm which hose you’re replacing: Upper = higher hose near top of radiator; Lower = lower hose near bottom of radiator.
• Know your clamp type: a “spring clamp” is the factory pinch-style clamp; you squeeze it with hose clamp pliers (specialty).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Relieve cooling-system pressure (cold engine only)

• Use nitrile gloves and safety glasses.
• Slowly loosen the coolant reservoir cap by hand to release any remaining pressure.
• If your Prius has a radiator cap, loosen it slowly by hand as well.

Step 2: Raise the front and remove the lower engine undercover

• Use floor jack (rated 2-ton minimum) to lift the front center jacking point.
• Place jack stands (rated 2-ton minimum) under the proper front support points.
• Use 10mm socket and 1/4" ratchet to remove undercover bolts.
• Use trim clip removal tool to remove plastic clips.
• Reinstall later and Torque to 5 Nm (44 in-lbs).

Step 3: Drain enough coolant to get below the hose level

• Position a drain pan (at least 2 gallons) under the radiator drain area.
• Use flashlight to locate the radiator drain cock (small plastic drain).
• Open the drain cock by hand; if tight, use channel-lock pliers gently.
• Drain until the coolant level is below the hose you’re replacing, then close the drain cock by hand (snug only).

Step 4: Remove the old hose clamp(s)

• For a spring clamp, use hose clamp pliers (specialty) to squeeze the clamp and slide it back on the hose.
• For a worm-gear clamp, loosen it with 10mm socket and 1/4" ratchet and slide it back.

Step 5: Remove the old radiator hose

• Twist the hose by hand to break it loose from the radiator/engine necks.
• If stuck, carefully work around the hose end with a pick tool to break the seal, then pull it off.
• Use shop towels to catch any remaining coolant.

Step 6: Prep and install the new hose

• Compare the new hose to the old one (same length and bends).
• Slide new clamp(s) onto the hose before installing it.
• Push the hose fully onto each neck until it bottoms out.
• Reposition the clamp so it sits behind the raised “bead” on the neck.

Step 7: Tighten/position the clamp(s) correctly

• For spring clamps, use hose clamp pliers (specialty) to move the clamp into position and release it.
• For worm-gear clamps, tighten with 10mm socket and 1/4" ratchet until snug (do not crush the hose).

Step 8: Refill coolant

• Install a spill-free funnel kit (specialty) on the reservoir or radiator fill point (whichever your Prius uses).
• Slowly add Toyota Super Long Life Coolant (pink, pre-mixed 50/50) until the level stays up.
• Squeeze the upper radiator hose by hand a few times to help push air out.

Step 9: Bleed air using Prius Maintenance Mode (engine will run continuously)

• Keep the car outside or in a well-ventilated area.
• With foot off brake, press POWER twice to IG-ON.
• Fully press and release accelerator 2 times.
• Shift to N, fully press and release accelerator 2 times.
• Shift to P, fully press and release accelerator 2 times.
• Hold brake and press POWER to READY; “Maintenance Mode” / “Inspection Mode” should appear.
• Set HVAC to full heat and fan medium to help circulation.
• Let the engine run while you watch the funnel level; add coolant as bubbles purge.
• Stop if temperature warning appears.

Step 10: Finish up and reinstall the undercover

• When bubbles stop and heat output is steady, turn the car OFF and let it cool 15-30 minutes.
• Top off coolant to the correct mark (FULL when cold) and reinstall the cap by hand.
• Reinstall the undercover using 10mm socket and trim clip removal tool.
• Torque to 5 Nm (44 in-lbs).

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✅ After Repair

• Start the Prius and check for leaks at both ends of the new hose.
• Bring it to operating temperature and confirm cabin heat works normally.
• After a full cool-down, recheck the reservoir level and top off if needed.
• Look under the car the next morning for any drips.

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💰 DIY vs Shop Cost

Shop Cost: $250-$550 (parts + labor)

DIY Cost: $40-$120 (parts only)

You Save: $130-$510 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-3.0 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.