🔧 Altima - Thermostat Replacement

Replacing the thermostat on your Altima helps restore proper engine temperature control. A stuck-open thermostat can cause slow warm-up and poor heat, while a stuck-closed thermostat can cause overheating.

Difficulty Level: Intermediate | Estimated Time: 2-3 hours

---

⚠️ Safety & Precautions

• ⚠️ Work only on a completely cool engine. Hot coolant can cause serious burns.
• ⚠️ Keep pets and children away from drained coolant. Engine coolant is toxic.
• ⚠️ Do not open the radiator cap or coolant reservoir cap while the engine is hot.
• ⚠️ Disconnecting the battery is not normally required for this repair, but keep tools away from the battery terminals.
• ⚠️ Use jack stands if you raise the front of the vehicle. Never rely on a floor jack alone.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 12mm socket
• 3/8-inch ratchet
• 3/8-inch extension, 6-inch
• Torque wrench, inch-pound range
• Flat-blade screwdriver
• Hose clamp pliers
• Drain pan, 2-gallon minimum
• Plastic scraper
• Funnel
• Cooling system spill-free funnel kit
• Floor jack, rated 2-ton minimum
• Jack stands, rated 2-ton minimum
• Wheel chocks
• Nitrile gloves
• Safety glasses
• Shop towels

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Engine thermostat - Qty: 1
• Thermostat housing gasket or O-ring - Qty: 1
• Nissan-compatible blue long-life coolant, premixed 50/50 - Qty: 1-2 gallons
• Distilled water - Qty: 1 gallon

---

📋 Before You Begin

• 🅿️ Park your Altima on level ground and set the parking brake.
• 🧊 Let the engine cool for at least 3-4 hours before opening the cooling system.
• 🚗 Chock the rear wheels with wheel chocks before lifting the front.
• ♻️ Place a drain pan under the front passenger-side area to catch coolant.
• 🧰 A thermostat is a temperature-controlled valve that opens to let coolant flow through the radiator.
• 🧰 A torque wrench tightens bolts to the correct tightness so small aluminum parts are not cracked.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Raise and Secure the Front

• Use the floor jack, rated 2-ton minimum to lift the front of your Altima at the front center jacking point.
• Place jack stands, rated 2-ton minimum under the front side support points.
• Lower the vehicle gently onto the jack stands and shake the vehicle lightly to confirm it is stable.
• Put on safety glasses and nitrile gloves.
• Never work under a jack only.

Step 2: Remove the Lower Engine Splash Shield

• Use a 10mm socket, 3/8-inch ratchet, and 3/8-inch extension, 6-inch to remove the lower splash shield fasteners.
• Set the splash shield and fasteners aside in order.
• If any plastic clips are present, use a flat-blade screwdriver to gently release them.

Step 3: Drain Some Coolant

• Make sure the engine is cool, then slowly loosen the coolant reservoir cap by hand to release any leftover pressure.
• Place the drain pan, 2-gallon minimum under the radiator drain area.
• Use a flat-blade screwdriver if needed to open the radiator drain cock carefully.
• Drain enough coolant so the level is below the thermostat housing, usually about 1 gallon.
• Close the radiator drain cock by hand. Do not overtighten it.

Step 4: Locate the Thermostat Housing

• Follow the lower radiator hose from the radiator toward the engine.
• The hose connects to the thermostat housing on the engine side.
• Use shop towels to wipe the area clean before opening it.
• Clean parts are easier to seal.

Step 5: Remove the Lower Radiator Hose

• Use hose clamp pliers to squeeze the lower radiator hose clamp.
• Slide the clamp back onto the hose.
• Twist the hose gently by hand to break it loose.
• If the hose is stuck, use a flat-blade screwdriver carefully between the hose and housing edge, but do not gouge the aluminum.
• Pull the hose off and aim it into the drain pan, 2-gallon minimum.

Step 6: Remove the Thermostat Housing

• Use a 10mm socket, 3/8-inch ratchet, and 3/8-inch extension, 6-inch to remove the thermostat housing bolts.
• Hold the housing with one hand as the last bolt comes out.
• Pull the housing straight off the engine.
• Note the direction of the old thermostat before removing it.

Step 7: Remove the Old Thermostat and Clean the Sealing Surface

• Remove the old thermostat by hand.
• Use a plastic scraper to clean old gasket material or residue from the housing and engine mating surfaces.
• Wipe the surfaces with shop towels.
• Do not use a metal scraper because it can scratch the aluminum and cause leaks.

Step 8: Install the New Thermostat

• Install the engine thermostat in the same direction as the old one.
• If the thermostat has a small jiggle valve or bleed pin, position it upward at the 12 o’clock position.
• Install the thermostat housing gasket or O-ring in its groove.
• Make sure the gasket sits flat and is not pinched.
• A pinched gasket will leak.

Step 9: Reinstall the Thermostat Housing

• Place the thermostat housing squarely against the engine by hand.
• Start all bolts by hand first to prevent cross-threading.
• Use a 10mm socket and 3/8-inch ratchet to snug the bolts evenly.
• Use the torque wrench, inch-pound range to tighten the thermostat housing bolts to Torque to 9.8 Nm (87 in-lbs).
• Do not overtighten. The housing and engine are aluminum and can crack.

Step 10: Reconnect the Lower Radiator Hose

• Push the lower radiator hose fully onto the thermostat housing by hand.
• Use hose clamp pliers to move the clamp back to its original position.
• Make sure the clamp sits behind the raised bead on the housing neck.

Step 11: Refill the Cooling System

• Install the cooling system spill-free funnel kit on the coolant reservoir or radiator fill point as applicable.
• Use a funnel to add Nissan-compatible blue long-life coolant, premixed 50/50 slowly.
• Fill until the coolant level stays steady near the full mark.
• If concentrated coolant is used instead of premix, mix it 50/50 with distilled water before pouring.

Step 12: Bleed Air from the Cooling System

• Set the cabin heater controls to full hot and fan on low.
• Start the engine and let it idle with the spill-free funnel attached.
• Watch for air bubbles rising through the funnel.
• As the engine warms up, add coolant as needed to keep the funnel from running empty.
• When the upper radiator hose gets hot and the cooling fans cycle on, the thermostat has opened.
• Use safety glasses and keep hands away from fans and belts.

Step 13: Check for Leaks

• With the engine idling, use a flashlight if available to inspect the thermostat housing and lower radiator hose area.
• Use shop towels to dab suspected wet areas. Do not touch hot parts.
• If leaks appear, shut the engine off and let it cool before tightening or reseating anything.

Step 14: Reinstall the Lower Splash Shield

• Once there are no leaks, shut the engine off and let it cool slightly.
• Use a 10mm socket, 3/8-inch ratchet, and 3/8-inch extension, 6-inch to reinstall the lower splash shield fasteners.
• Tighten the splash shield fasteners snugly by hand tool only.

Step 15: Lower the Vehicle

• Use the floor jack, rated 2-ton minimum to lift the front slightly off the jack stands.
• Remove the jack stands, rated 2-ton minimum.
• Lower your Altima slowly to the ground.
• Remove the wheel chocks.

---

✅ After Repair

• ✅ Let the engine cool completely, then recheck the coolant level and top off with Nissan-compatible blue long-life coolant, premixed 50/50 if needed.
• ✅ Test drive for 10-15 minutes while watching the temperature gauge. It should stay near the normal middle range.
• ✅ After the test drive, park and check again for leaks around the thermostat housing and lower radiator hose.
• ✅ Properly recycle old coolant. Do not pour it on the ground or into drains.
• ✅ If the heater blows cold at idle or the temperature gauge fluctuates, air may still be trapped and the system should be bled again.

---

💰 DIY vs Shop Cost

Shop Cost: $250-$450 (parts + labor)

DIY Cost: $35-$90 (parts only)

You Save: $160-$360 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-2.0 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.