🔧 Durango - Thermostat Replacement

The thermostat controls engine temperature by opening and closing to let coolant flow to the radiator. If it sticks open you may get low heat and slow warm-up; if it sticks closed you can overheat. On your Durango, the thermostat is built into a thermostat housing, so you replace the whole housing assembly.

Difficulty Level: Intermediate | Estimated Time: 2-4 hours

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⚠️ Safety & Precautions

• ⚠️ Never open the coolant system hot—let the engine cool completely.
• ⚠️ Support the Durango with jack stands on solid level ground—never rely on a jack.
• ⚠️ Coolant is toxic—keep away from kids/pets and clean spills immediately.
• ⚠️ Disconnect the negative battery cable before working near the alternator.
• ⚠️ Properly dispose of old coolant (most parts stores accept it).

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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
• Drain pan (at least 3-gallon)
• Funnel
• Spill-free coolant funnel kit (specialty)
• Ratchet (3/8" drive)
• Socket set (metric)
• 8mm socket
• 10mm socket
• 13mm socket
• 15mm socket
• Extension set (3/8" drive)
• Torque wrench (3/8" drive, inch-pound or low Nm capable)
• Flathead screwdriver
• Hose clamp pliers
• Serpentine belt tool (specialty)
• Trim clip removal tool
• Razor scraper
• Shop towels

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Thermostat housing assembly (with thermostat and seal) - Qty: 1
• Engine coolant (Mopar OAT compatible 50/50 premix) - Qty: 2-3 gallons
• Distilled water - Qty: 1 gallon
• Upper radiator hose clamp (optional if original is weak/damaged) - Qty: 1

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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).
• Disconnect the negative battery cable using a 10mm socket.
• Take a photo of belt routing first.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Raise the front and remove the lower access panel (if equipped)

• Lift the front with a floor jack (rated 3-ton minimum) and support with jack stands (rated 3-ton minimum).
• Remove any lower splash shield/air dam using a trim clip removal tool and 8mm socket.

Step 2: Drain the coolant

• Place a drain pan (at least 3-gallon) under the radiator drain area.
• Slowly loosen the coolant reservoir cap by hand to release any leftover pressure.
• Open the radiator drain (petcock) if accessible; if not, loosen the lower radiator hose clamp using hose clamp pliers and carefully crack the hose loose.
• Let coolant drain until the flow is minimal.

Step 3: Remove the engine cover and intake ducting

• Pull up to remove the engine cover by hand (it is held by rubber grommets).
• Loosen intake hose clamps using a flathead screwdriver.
• Remove the intake tube/air duct as needed for access.

Step 4: Remove the serpentine belt from the alternator area

• Use a serpentine belt tool (specialty) to rotate the belt tensioner and slip the belt off the alternator pulley.
• A serpentine belt tool is a long handled wrench for tight spaces.
• Leave the belt routed on other pulleys if possible, so re-install is easier.

Step 5: Remove the alternator for access (common on the 3.6L)

• Unplug the alternator electrical connector by hand (press the tab and pull).
• Remove the alternator main power nut using a 10mm socket, then move the cable aside.
• Remove alternator mounting bolts using a 13mm socket and ratchet (3/8" drive).
• Lift the alternator out and set it aside safely.

Step 6: Remove the upper radiator hose from the thermostat housing

• Place shop towels under the housing to catch leftover coolant.
• Release the hose clamp with hose clamp pliers.
• Twist the hose gently to break it free, then pull it off.

Step 7: Remove the thermostat housing assembly

• Remove the thermostat housing bolts using a 10mm socket with extensions (3/8" drive).
• Pull the housing straight off and drain any coolant into the drain pan (at least 3-gallon).
• Clean the sealing surface with a razor scraper and shop towels until it is smooth and dry.
• Do not gouge the aluminum surface.

Step 8: Install the new thermostat housing

• Confirm the new housing seal is seated correctly (do not add RTV unless your part instructions require it).
• Install the new housing and start all bolts by hand first.
• Tighten bolts evenly using a 10mm socket.
• Torque to 12 Nm (106 in-lbs) using a torque wrench (3/8" drive, inch-pound or low Nm capable).

Step 9: Reconnect the hose and reinstall the alternator and belt

• Reinstall the upper radiator hose and clamp using hose clamp pliers.
• Reinstall the alternator and mounting bolts using a 13mm socket.
• Torque to 54 Nm (40 ft-lbs) for alternator mounting bolts.
• Reconnect the alternator power cable using a 10mm socket and reconnect the electrical plug.
• Route the belt correctly and use the serpentine belt tool (specialty) to slip the belt back onto the alternator pulley.

Step 10: Refill and bleed the cooling system

• Lower the Durango to the ground (remove jack stands (rated 3-ton minimum) and lower with the floor jack (rated 3-ton minimum)).
• Fill the coolant reservoir using a spill-free coolant funnel kit (specialty) and a funnel as needed.
• Use Engine coolant (Mopar OAT compatible 50/50 premix). If mixing concentrate, use distilled water.
• Start the engine and set the heater to max heat, fan on low.
• Let it idle until the engine reaches operating temp and you feel steady heat from the vents.
• Watch the coolant level and add as it drops (air is purging). Squeeze the upper radiator hose carefully to help burp air.
• Shut the engine off, let it cool, then recheck and top off the reservoir to the correct mark.

Assumption: Access requires alternator removal (common on the 3.6L); your layout may vary slightly.

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✅ After Repair

• Start the engine and check for leaks around the thermostat housing and hose connection.
• Road test 10–15 minutes, then recheck coolant level after a full cool-down.
• Confirm the temperature gauge stays normal and cabin heat works.
• If you get a check-engine light, scan for codes (overheat/thermostat rationality codes can set if air is trapped).

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💰 DIY vs Shop Cost

Shop Cost: $350-$650 (parts + labor)

DIY Cost: $60-$140 (parts only)

You Save: $210-$590 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2-4 hours.

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🎯 Ready to get started?

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