🔧 Forester - Radiator Hose Replacement

Replacing a radiator hose on your Forester is mainly about working safely around hot coolant, removing the old hose and clamps, and refilling/bleeding the cooling system so it doesn’t overheat. The upper hose is usually easier from the top, while the lower hose often needs underbody access.

Quick question: Are you replacing the upper hose, lower hose, or both?

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

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⚠️ Safety & Precautions

• ⚠️ Only work on a stone-cold engine; hot coolant can cause severe burns.
• ⚠️ Never open the radiator cap when hot; the system is pressurized.
• ⚠️ Support the vehicle with jack stands on solid ground; never rely on a jack alone.
• ⚠️ Keep coolant off belts and pulleys; wipe spills immediately.
• ⚠️ Coolant is toxic; keep away from pets and kids, and dispose properly.

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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
• Drain pan (at least 10-quart)
• Funnel (coolant-safe)
• Hose clamp pliers
• Slip-joint pliers
• Pick tool
• Flathead screwdriver
• 10mm socket
• 3/8" ratchet
• 3" extension (3/8" drive)
• Trim clip removal tool
• Shop towels

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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: 4
• Subaru-approved premixed coolant (blue) - Qty: 2 gallons

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📋 Before You Begin

• 🅿️ Park on level ground, set the parking brake, and let the engine cool completely.
• 🧱 Chock the rear wheels.
• ⬆️ If doing the lower hose, raise the front with a floor jack and support with jack stands.
• 🧼 Place a drain pan under the radiator area before loosening anything.
• 🔎 Identify clamp type: Subaru commonly uses spring clamps (constant-tension). A spring clamp is the clamp you squeeze with pliers to slide it back.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the lower under cover (if needed)

• If accessing the lower hose, use a 10mm socket, 3/8" ratchet, and trim clip removal tool to remove the fasteners and take off the under cover.
• Set hardware aside in a small tray so nothing gets lost.

Step 2: Drain coolant to a level below the hose

• Position a drain pan (at least 10-quart) under the radiator.
• Slowly loosen the radiator cap (top of radiator) using your hand with a shop towel over it, only if the engine is fully cold.
• Drain from the radiator drain (if you use it) until the coolant level is below the hose you’re replacing.
• Drain less coolant to reduce mess.

Step 3: Remove the hose clamps

• For spring clamps, use hose clamp pliers (or slip-joint pliers) to squeeze the clamp tabs and slide the clamp back on the hose.
• For screw-type clamps, loosen using a flathead screwdriver until the clamp is free and slide it back.

Step 4: Remove the old radiator hose

• Twist the hose by hand to break it loose, then pull it off.
• If it’s stuck, carefully work the edge free with a pick tool (don’t gouge the radiator neck or engine outlet).
• Use shop towels to catch remaining coolant that will spill.

Step 5: Prep the fittings and compare parts

• Wipe the radiator neck and engine-side outlet clean using shop towels.
• Compare the new hose to the old one (length, bends, diameter) before installing.
• If your new hose came with new clamps, use them.

Step 6: Install the new hose and position clamps

• Slide the clamps onto the hose first.
• Push the hose fully onto each fitting until it bottoms out (you should not see an unseated gap).
• Position each clamp behind the raised bead on the fitting, then release/tighten the clamp:
  • Spring clamp: release using hose clamp pliers so it clamps down evenly.
  • Screw clamp: tighten with a flathead screwdriver until snug (do not crush the hose).

Step 7: Reinstall the under cover (if removed)

• Reinstall the cover using a 10mm socket, 3/8" ratchet, and trim clip removal tool.

Step 8: Refill coolant and bleed air

• Fill the radiator slowly using a funnel (coolant-safe) with Subaru-approved premixed coolant (blue).
• Fill the overflow reservoir to the correct level.
• Start the engine and set the heater to HOT and fan on LOW.
• Let the engine warm up while you watch the coolant level at the radiator neck and add as needed.
• “Bleeding” (also called “burping”) means letting trapped air escape so it won’t cause overheating; gently squeeze the upper hose a few times using your hands (with gloves) to help move air.
• When the radiator fans cycle and the heater blows hot, top off again and install the radiator cap.

Step 9: Check for leaks

• With the engine running, inspect both hose ends using a bright light and shop towels to spot seepage.
• Shut the engine off, let it cool, then recheck the overflow level and top off if needed using a funnel.

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✅ After Repair

• 🧪 Test drive 10-15 minutes, then recheck for leaks and recheck overflow level after a full cool-down.
• 🌡️ Watch the temperature gauge closely on the first drive; stop if it rises above normal.
• 🧼 Clean any spilled coolant and dispose of old coolant properly.

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💰 DIY vs Shop Cost

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

DIY Cost: $60-$160 (parts only)

You Save: $190-$390 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.