🔧 WRX - Radiator Hose Replacement

Replacing a radiator hose stops coolant leaks and prevents overheating. On your WRX, you’ll usually replace the upper hose (top of radiator) or the lower hose (bottom of radiator) and then refill/bleed the cooling system to remove trapped air.

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

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⚠️ Safety & Precautions

• Never open the radiator cap on a hot engine—hot coolant can spray out and burn you.
• Support the car with jack stands; never work under a car held only by a jack.
• Coolant is toxic—keep it off the ground and away from kids/pets; dispose of it properly.
• Wear gloves and safety glasses—coolant and clamps can slip suddenly.
• Battery disconnect is not required for this job.

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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 2-gallon)
• Spill-free coolant funnel kit (specialty)
• Hose clamp pliers (specialty)
• Channel-lock pliers
• Flathead screwdriver
• Pick tool (angled) (specialty)
• Trim clip removal tool
• 10mm socket
• 3/8" drive ratchet
• 3" extension
• Torque wrench (3/8" drive)
• 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: 2-4
• Subaru Super Coolant (blue) premix - Qty: 1-2 gallons
• Distilled water - Qty: 1 gallon

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📋 Before You Begin

• Park on level ground, set the parking brake, and place wheel chocks behind the rear wheels.
• Let the engine cool fully (radiator hoses should feel cool to the touch).
• If you’re doing the lower hose, plan to raise the front of the car and remove the lower engine under cover.
• Have a drain pan ready—some coolant will come out even if you don’t fully drain the system.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Relieve pressure safely

• Put on safety glasses and nitrile gloves.
• Place shop towels over the radiator cap.
• With the engine fully cool, slowly twist the radiator cap to the first stop to release any leftover pressure, then remove it.

Step 2: Raise the front (recommended for lower hose access)

• Use a floor jack (rated 3-ton minimum) to lift the front of the car.
• Set the car onto jack stands (rated 3-ton minimum) and lightly shake the car to confirm it’s stable.

Step 3: Remove the lower engine under cover

• Use a trim clip removal tool to remove the plastic push clips.
• Use a 10mm socket, 3/8" drive ratchet, and 3" extension to remove the under cover bolts.
• Reinstall torque: Torque to 7.5 Nm (5.5 ft-lbs).

Step 4: Drain coolant to below the hose you’re replacing

• Slide a drain pan (at least 2-gallon) under the radiator drain cock.
• Open the drain cock carefully (by hand if possible; use channel-lock pliers gently only if stuck).
• Drain until the coolant level is below the hose connection you’re opening, then close the drain cock.
• Less draining = less mess.

Step 5: Remove the upper radiator hose (if replacing upper)

• Locate the upper hose at the top of the radiator.
• If equipped with spring clamps, squeeze the clamp using hose clamp pliers (specialty) and slide it back on the hose.
• If equipped with worm-gear clamps, loosen using a flathead screwdriver and slide the clamp back.
• Twist the hose to break it loose, then pull it off by hand. If it’s stuck, carefully work the edge with an pick tool (angled) (specialty) to release it (do not gouge the radiator neck).

Step 6: Remove the lower radiator hose (if replacing lower)

• From underneath, locate the lower hose at the bottom of the radiator.
• Move the clamp back using hose clamp pliers (specialty) or loosen with a flathead screwdriver (depending on clamp type).
• Pull the hose off the radiator first, then off the engine side. Keep the drain pan underneath—more coolant will spill here.

Step 7: Install the new hose and position clamps correctly

• Compare old vs new hose shape/length before installing.
• Slide the clamps onto the hose first.
• Push the hose fully onto the radiator neck/engine fitting until it bottoms out.
• Position the clamp behind the bead (raised lip) on the fitting, then release/tighten it.
• Wipe the area with shop towels so you can spot leaks later.

Step 8: Reinstall the under cover

• Reinstall bolts using a 10mm socket, 3/8" drive ratchet, and 3" extension.
• Tighten with a torque wrench (3/8" drive): Torque to 7.5 Nm (5.5 ft-lbs).
• Reinstall the push clips using your hands or the trim clip removal tool.

Step 9: Refill and bleed air from the cooling system

• Install the spill-free coolant funnel kit (specialty) onto the radiator fill neck.
• Slowly add Subaru Super Coolant (blue) premix until the radiator is full.
• Fill the coolant overflow tank to the “FULL” line.
• Start the engine and set the cabin heat to hottest temperature (this helps circulate coolant through the heater core).
• Let the engine idle and watch the funnel level; add coolant as the level drops.
• Keep idling until the radiator fans cycle on/off at least once and you see fewer/no bubbles.
• Shut the engine off, let it cool, then top off the radiator and overflow tank as needed.

Step 10: Final leak check

• With a flashlight, inspect both hose ends for seepage.
• Confirm clamps are straight and seated behind the fitting bead.

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✅ After Repair

• Take a 10-15 minute drive, then recheck for leaks with a flashlight.
• After the engine fully cools, recheck the overflow tank level and top off if needed.
• If the temperature gauge rises above normal or you get no cabin heat, stop and re-bleed air using the spill-free coolant funnel kit (specialty).
• Dispose of old coolant properly (never pour it on the ground).

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💰 DIY vs Shop Cost

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

DIY Cost: $40-$140 (parts only)

You Save: $110-$510 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.