🔧 Forester - Radiator Hose Replacement

Replacing a radiator hose means draining some coolant, removing the old hose and clamps, and installing the new hose without leaks. On your Forester there are two main radiator hoses: the upper (top of radiator to engine) and the lower (bottom of radiator to engine).

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

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⚠️ Safety & Precautions

• ⚠️ Never open the radiator cap hot—coolant can spray and burn you.
• ⚠️ Support the Forester on jack stands before going underneath.
• ⚠️ Coolant is toxic—keep it off skin, off paint, and away from kids/pets.
• ⚠️ Clean spills immediately; coolant is slippery.
• 🔋 Battery disconnect is not required for this job.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• 12mm socket
• 10mm socket
• 3/8" drive ratchet
• 6" socket extension
• Trim clip removal tool
• Hose clamp pliers (specialty)
• Slip-joint pliers
• Pick tool
• Drain pan (at least 10-quart)
• Funnel
• Shop rags
• 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
• Engine coolant (Subaru-compatible premix) - Qty: 1-2 gallons

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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).
• Set the HVAC to heat on HIGH and fan on LOW for the refill step later.
• Plan to capture coolant in a drain pan and dispose of it properly.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Raise the front and remove the lower splash shield

• Use a floor jack (rated 3-ton minimum) to lift the front jacking point.
• Set the Forester onto jack stands (rated 3-ton minimum) at the front support points.
• Remove the lower engine splash shield using a 12mm socket, 10mm socket, and trim clip removal tool.

Step 2: Relieve pressure safely

• Place a shop rag over the radiator cap.
• Slowly loosen the cap to the first stop to release any leftover pressure, then remove it fully.

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

• Position a drain pan (at least 10-quart) under the radiator drain area.
• Use slip-joint pliers (or your fingers if it’s hand-turn style) to open the radiator drain cock and let coolant drain.
• Stop draining once the coolant level is below the hose you’re replacing (upper usually needs less draining than lower).

Step 4: Remove the old hose (upper OR lower)

• Locate the hose you’re replacing using a flashlight.
• Move the clamp back from the hose end using hose clamp pliers (specialty).
• If the clamp is a screw-type, loosen it with a 10mm socket or slip-joint pliers (depending on clamp style).
• Twist the hose to break it free:
  • Use slip-joint pliers to gently rotate the hose near the end.
  • If it’s stuck, use a pick tool to carefully lift the hose edge to let air in, then twist again.
• Pull the hose off and aim it into the drain pan—more coolant will spill.
• Don’t gouge the radiator nipple.

Step 5: Prep the fittings and compare parts

• Wipe the radiator and engine hose fittings clean using shop rags.
• Match the new hose to the old one (shape, bend direction, and length).
• Slide the clamps onto the new hose before installing it using hose clamp pliers (specialty).

Step 6: Install the new hose and position clamps correctly

• Push the hose fully onto the fitting until it bottoms out (use your hands and a shop rag for grip).
• Reposition the clamp so it sits behind the raised “bead” on the fitting using hose clamp pliers (specialty).
• Repeat for the other end of the hose.
• Double-check the hose routing:
  • It should not rub on fans, belts, or sharp edges.
  • It should not be kinked or twisted.

Step 7: Close the drain and refill coolant

• Close the radiator drain cock using slip-joint pliers (snug only—do not overtighten).
• Refill the radiator slowly using a funnel and engine coolant (Subaru-compatible premix).
• Fill the overflow reservoir to the correct level using a funnel.

Step 8: Bleed air (“burp”) the cooling system and check for leaks

• Start the engine and let it idle with the radiator cap off.
• Set HVAC to heat HIGH (you already did) and keep an eye on coolant level.
• As the engine warms up, add coolant as the level drops using a funnel.
• Carefully squeeze the upper radiator hose a few times (use gloves) to help move trapped air.
• Watch for leaks at both hose ends using a flashlight.
• Once the thermostat opens (you’ll usually see flow and/or a sudden level drop), top off again, then install the radiator cap.

Step 9: Reinstall the splash shield and lower the vehicle

• Reinstall the splash shield using a 10mm socket, 12mm socket, and trim clip removal tool.
• Lift slightly with the floor jack (rated 3-ton minimum), remove jack stands, then lower the Forester.

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✅ After Repair

• Let the engine reach normal temperature and confirm the heater blows hot air.
• Check for leaks again with a flashlight, especially after a short drive.
• After the engine fully cools, recheck the overflow reservoir level and top off if needed using a funnel.
• If the temperature gauge rises abnormally, shut it off and recheck for trapped air or leaks.

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💰 DIY vs Shop Cost

Shop Cost: $220-$450 (parts + labor)

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

You Save: $180-$310 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.