🔧 Thermostat - Replacement

Your Accord’s thermostat controls engine warm-up and coolant flow. If it’s stuck open, the engine runs too cool; if it’s stuck closed, it can overheat fast. Replacing it means draining some coolant, removing the thermostat housing, installing the new thermostat and seal, then refilling and bleeding the cooling system.

Difficulty Level: Intermediate | Estimated Time: 1.5-3 hours

---

⚠️ Safety & Precautions

• Work only on a cold engine. Hot coolant can cause severe burns.
• Use jack stands if you raise the car. Never rely on a jack alone.
• Keep coolant away from pets and children; it is toxic.
• Battery disconnect is not required for this repair.
• Use caution around the radiator fan area if the engine is run during bleeding.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 3/8-inch ratchet
• 10mm socket
• 12mm socket
• Socket extension
• Drain pan
• Funnel
• Hose clamp pliers
• Pick tool
• Torque wrench
• Gloves
• Safety glasses
• Jack and jack stands
• Shop towels

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Thermostat - Qty: 1
• Thermostat gasket / O-ring - Qty: 1
• Honda Type 2 coolant - Qty: 1-2 gallons
• Distilled water - Qty: 1-2 gallons

---

📋 Before You Begin

• Park on level ground and set the parking brake.
• Let the engine cool completely before opening any cooling system parts.
• If the engine cover is installed, remove it first.
• Have a drain pan ready before opening the cooling system.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Drain the coolant

• Place the drain pan under the radiator drain area.
• Use a funnel only after draining later; for now, open the radiator cap slowly if the engine is fully cold.
• Use the 3/8-inch ratchet and 10mm socket if needed to remove any lower splash shield fasteners for access.
• Open the radiator drain plug and drain enough coolant to get the level below the thermostat housing.
• Torque to 29 Nm (21 ft-lbs) when reinstalling the drain plug, if equipped with a torque spec on your drain fitting.

Step 2: Remove the air intake ducting if needed

• Use the 10mm socket to remove the intake duct or air box fasteners if they block access to the thermostat housing.
• Lift the ducting out carefully and set it aside.
• Label every hose clip you remove.

Step 3: Remove the thermostat housing

• Locate the thermostat housing at the engine coolant outlet.
• Use the hose clamp pliers to release the radiator hose clamp.
• Twist the hose gently to break it free, then pull it off the housing.
• Use the 12mm socket and 3/8-inch ratchet with an extension to remove the thermostat housing bolts.
• Remove the housing and old thermostat together if they come out as an assembly.

Step 4: Remove the old thermostat and seal

• Note the thermostat orientation before removal.
• Use the pick tool to remove the old gasket or O-ring.
• Clean the housing and engine mating surfaces with a shop towel.
• Do not scratch the sealing surface.

Step 5: Install the new thermostat

• Install the new thermostat in the same orientation as the old one.
• Install the new thermostat gasket / O-ring.
• Set the housing back in place by hand first.
• Install the bolts finger-tight, then use the torque wrench and 12mm socket to tighten the housing bolts to 9.8 Nm (7.2 ft-lbs).

Step 6: Reinstall the hose and intake parts

• Push the radiator hose fully onto the housing neck.
• Use the hose clamp pliers to position the clamp correctly.
• Reinstall the intake ducting and tighten its fasteners with the 10mm socket.

Step 7: Refill and bleed the cooling system

• Close the drain plug if it was opened.
• Use a funnel to fill the system with the correct coolant mix.
• Fill slowly to reduce air pockets.
• Start the engine with the radiator cap off and let it reach operating temperature.
• Turn the heater to HOT and the blower to low.
• Watch for bubbles and top off as the level drops.
• Install the radiator cap once the coolant level stabilizes and the upper hose is hot.

Step 8: Check for leaks and final level

• Inspect the thermostat housing, hose connection, and drain plug for leaks.
• Let the engine cool fully, then recheck the coolant level in the reservoir and radiator.
• Top off as needed with the correct coolant mix.

---

✅ After Repair

• Watch the temperature gauge on a short test drive.
• Confirm the heater blows hot air.
• Recheck for coolant leaks after the engine cools again.
• If the cooling fan runs unusually often or the temperature climbs, bleed the system again.

---

💰 DIY vs Shop Cost

Shop Cost: $280-$520 (parts + labor)

DIY Cost: $45-$120 (parts only)

You Save: $235-$400 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-3 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.