How to Replace Upper & Lower Radiator Hoses on a 2018 Subaru Crosstrek
Step-by-step cooling system hose swap with tools, parts list, coolant refill/bleed steps, and leak checks for 2018, 2019, 2020, 2021, 2022, 2023, 2024
How to Replace Upper & Lower Radiator Hoses on a 2018 Subaru Crosstrek
Step-by-step cooling system hose swap with tools, parts list, coolant refill/bleed steps, and leak checks for 2018, 2019, 2020, 2021, 2022, 2023, 2024
🔧 Crosstrek - Radiator Hose Replacement
Replacing a radiator hose means removing the old upper and/or lower hose, transferring or replacing the clamps, then refilling and bleeding the cooling system so it doesn’t overheat. Hoses can crack, swell, or leak with age, and a small leak can quickly turn into a breakdown.
Difficulty Level: Intermediate | Estimated Time: 1.0-2.0 hours
⚠️ Safety & Precautions
- ⚠️ Never open the radiator cap on a hot engine; hot coolant can spray out and burn you.
- ⚠️ Support the vehicle with jack stands before working underneath; never rely on a jack alone.
- ⚠️ Keep coolant away from pets and kids; it’s toxic and has a sweet smell.
- ⚠️ Wear gloves and safety glasses; coolant can irritate skin and eyes.
- 🔋 Battery disconnect is not required for this repair.
🔧 Required Tools
You'll need the following tools for this repair:
- Smooth-jaw hose clamp pliers (specialty)
- Slip-joint pliers
- Pick tool (small hook) (specialty)
- Flathead screwdriver
- 10mm socket
- 3/8" drive ratchet
- Drain pan (at least 8 quarts)
- Spill-free coolant funnel kit (specialty)
- Shop rags
- Floor jack (rated 2-ton minimum)
- Jack stands (rated 2-ton minimum)
- Wheel chocks
- Nitrile gloves
- Safety glasses
🔩 Required Parts
HowToo sells all the parts you need for this repair:
- Upper radiator hose - Qty: 1
- Lower radiator hose - Qty: 1
- Radiator hose clamp set - Qty: 1
- Engine coolant (Subaru-compatible premix 50/50) - Qty: 2 gallons
📋 Before You Begin
- 🅿️ Park on level ground, set the parking brake, and chock the rear wheels.
- 🧊 Let the engine cool completely (ideally 2+ hours).
- 🧽 Lay rags under the radiator area to catch drips.
- 🧰 Quick tool note: hose clamp pliers are pliers that lock onto spring clamps so you can move them safely.
🔨 Step-by-Step Instructions
Follow these steps in order:
Step 1: Relieve pressure safely
- Put on nitrile gloves and safety glasses.
- Place shop rags around the radiator cap area.
- When the engine is fully cold, slowly loosen the radiator cap by hand to the first stop to release any leftover pressure, then remove it.
Step 2: Lift the front (helps access the lower hose)
- Use wheel chocks at the rear wheels.
- Use a floor jack (rated 2-ton minimum) to lift the front center jacking point.
- Set the vehicle onto jack stands (rated 2-ton minimum) before you go underneath.
Step 3: Drain enough coolant to get below hose level
- Place a drain pan (at least 8 quarts) under the radiator drain area.
- Open the radiator drain cock by hand (or carefully with a flathead screwdriver if needed) and drain coolant until the level is below the hoses.
- Close the drain cock snugly by hand when done. Don’t overtighten plastic drains.
Step 4: Remove the intake snorkel/duct (for working room)
- Use a 10mm socket with a 3/8" drive ratchet to remove the bolts/clips holding the upper intake snorkel/duct as needed.
- Move the ducting aside so you can clearly reach the upper hose connections.
Step 5: Remove the UPPER radiator hose (radiator to engine)
- Use smooth-jaw hose clamp pliers (specialty) to compress the spring clamp and slide it back a few inches on the hose.
- Repeat for the clamp at the other end of the upper hose.
- Twist the hose by hand to break it free from the fitting.
- If it’s stuck, carefully work around the edge with a pick tool (small hook) (specialty) to break the seal. Don’t gouge the plastic neck.
- Pull the hose off and aim it into the drain pan (at least 8 quarts) for any remaining coolant.
Step 6: Remove the LOWER radiator hose (radiator to engine)
- From below, reposition the drain pan (at least 8 quarts) under the lower hose area.
- Use smooth-jaw hose clamp pliers (specialty) to compress the spring clamp and slide it back on the hose.
- Twist the hose to break it free, then pull it off.
- If you can’t twist it, use slip-joint pliers gently on the hose (not on the radiator neck) to rotate it loose.
Step 7: Prep the fittings and install the new hose(s)
- Use shop rags to wipe the radiator neck(s) and engine fitting(s) clean.
- Slide the clamps onto the new hose before installing it.
- Push the hose fully onto the fitting until it bottoms out.
- Use smooth-jaw hose clamp pliers (specialty) to position the clamps in the same spot as factory (typically just behind the raised bead on the neck).
- Double-check the hose routing is not rubbing on belts, fans, or sharp edges.
Step 8: Reinstall the intake ducting
- Reinstall the snorkel/duct.
- Use a 10mm socket with a 3/8" drive ratchet to tighten fasteners securely (snug, do not strip plastic).
Step 9: Refill and bleed air from the cooling system
- Install a spill-free coolant funnel kit (specialty) onto the radiator fill neck.
- Slowly add engine coolant (Subaru-compatible premix 50/50) until the funnel stays about 1/3 full.
- Start the engine and set the heater to HOT (full warm) so coolant flows through the heater core.
- Let the engine idle and watch for air bubbles in the funnel; keep the level from dropping too low by adding coolant as needed.
- Once the cooling fans cycle on and off and bubbles slow down, gently raise rpm to about 2,000 for 10–15 seconds a couple times, then let it idle again.
- Shut the engine off, let it cool, then remove the funnel and install the radiator cap.
- Fill the coolant reservoir to the FULL line with the same coolant.
Step 10: Check for leaks
- With the engine running, inspect both ends of the hose(s) for seepage.
- Use shop rags to wipe and re-check after a minute.
✅ After Repair
- 🧪 Take a short 10–15 minute test drive, then re-check for leaks.
- 🌡️ Watch the temperature gauge closely; shut down if it rises abnormally.
- 🧊 After the engine fully cools, recheck the radiator level and reservoir level and top off if needed.
- 🧹 Dispose of old coolant properly (never dump it).
💰 DIY vs Shop Cost
Shop Cost: $250-$450 (parts + labor)
DIY Cost: $40-$120 (parts only)
You Save: $130-$410 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.
🎯 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.










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