🔧 Grand Cherokee - Thermostat Replacement

Replacing the thermostat on your Grand Cherokee means draining some coolant, removing the thermostat housing at the front of the 5.7L HEMI engine, installing a new thermostat and seal, then refilling and bleeding the cooling system. A stuck thermostat can cause overheating, slow warm-up, or incorrect engine temperature readings.

Difficulty Level: Beginner-Intermediate | Estimated Time: 1.5-2.5 hours

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⚠️ Safety & Precautions

• ⚠️ Only work on the cooling system when the engine is completely cold. Hot coolant can cause severe burns.
• 🧤 Wear gloves and safety glasses because coolant is toxic and irritating to skin and eyes.
• 🐾 Keep drained coolant away from children and pets. It tastes sweet but is poisonous.
• 🔋 Battery disconnect is not required for this repair.
• 🌡️ Do not open the coolant reservoir cap while the engine is hot.

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🔧 Required Tools

You'll need the following tools for this repair:

• 8mm socket
• 10mm socket
• 13mm socket
• 3/8-inch drive ratchet
• 3/8-inch drive extension set
• Torque wrench rated 10-80 ft-lbs
• Flat-blade screwdriver
• Hose clamp pliers
• Plastic trim clip remover
• Drain pan rated 2-gallon minimum
• Clean funnel
• Shop towels
• Plastic scraper
• Safety glasses
• Nitrile gloves

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Engine coolant thermostat - Qty: 1
• Thermostat seal - Qty: 1
• OAT coolant premix compatible with Chrysler MS-12106 - Qty: 1-2 gallons

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📋 Before You Begin

• 🅿️ Park your Grand Cherokee on level ground and set the parking brake.
• ❄️ Let the engine cool for at least 3-4 hours if it was recently driven.
• 🧴 Confirm you have the correct orange/purple OAT coolant type compatible with Chrysler MS-12106. Do not mix coolant types.
• 🪣 Place a drain pan under the front of the vehicle before opening any cooling system connection.
• 📌 A thermostat controls coolant flow so the engine warms up quickly and stays at the correct temperature.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the Engine Cover

• Use your hands to lift the plastic engine cover straight upward from the rubber mounting grommets.
• Set the cover aside in a safe place.
• Lift evenly to avoid cracking it.

Step 2: Remove the Intake Tube for Access

• Use a flat-blade screwdriver or 8mm socket to loosen the air intake tube clamp at the throttle body.
• Use the 8mm socket to loosen the clamp at the air filter box side.
• Disconnect any small breather hose from the intake tube by hand.
• Lift the intake tube out and set it aside.

Step 3: Slowly Open the Coolant Reservoir Cap

• Make sure the engine is cold.
• Use a shop towel over the coolant reservoir cap.
• Turn the cap slowly counterclockwise by hand to release any leftover pressure.
• Remove the cap fully once pressure is gone.

Step 4: Drain Some Coolant

• Place a drain pan rated 2-gallon minimum under the lower radiator area.
• If accessible, use your hand or pliers carefully on the radiator drain petcock and drain about 1 gallon of coolant.
• If the drain petcock is difficult to access, use hose clamp pliers to loosen the lower radiator hose clamp slightly and drain coolant carefully into the pan.
• Retighten the drain petcock by hand or reinstall the hose clamp with hose clamp pliers.
• Do not overtighten plastic drain fittings.

Step 5: Locate the Thermostat Housing

• Find the upper radiator hose where it connects to the front of the engine.
• The thermostat housing is the metal outlet that the hose attaches to.
• Use shop towels around the area to catch spilled coolant.

Step 6: Remove the Upper Radiator Hose from the Housing

• Use hose clamp pliers to squeeze the spring clamp on the upper radiator hose.
• Slide the clamp back along the hose.
• Twist the hose gently by hand to break it loose.
• Pull the hose off the thermostat housing.
• If stuck, use a flat-blade screwdriver gently between the hose and housing, but do not cut or gouge the hose.

Step 7: Remove the Thermostat Housing Bolts

• Use a 13mm socket, 3/8-inch drive ratchet, and 3/8-inch drive extension to remove the thermostat housing bolts.
• Keep the bolts together so they do not get lost.
• Pull the housing away from the engine by hand.
• Some coolant will spill, so keep the drain pan and shop towels in place.

Step 8: Remove the Old Thermostat and Seal

• Pull the old thermostat out by hand.
• Remove the old rubber seal by hand or with a plastic scraper.
• A plastic scraper removes old sealing material without scratching the aluminum surface.
• Clean the thermostat housing and engine mating surfaces with shop towels and the plastic scraper.
• Do not use metal scrapers because they can damage the sealing surface.

Step 9: Install the New Thermostat

• Install the new engine coolant thermostat into the engine opening in the same direction as the old one.
• Install the new thermostat seal so it sits flat and fully seated.
• If the thermostat has a small jiggle pin or bleed hole, position it at the top.
• Match the old thermostat orientation.

Step 10: Reinstall the Thermostat Housing

• Place the thermostat housing back onto the engine by hand.
• Start both bolts by hand first to avoid cross-threading.
• Use the 13mm socket and 3/8-inch drive ratchet to snug the bolts evenly.
• Use a torque wrench rated 10-80 ft-lbs to tighten the thermostat housing bolts to Torque to 28 Nm (21 ft-lbs).

Step 11: Reconnect the Upper Radiator Hose

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

Step 12: Reinstall the Intake Tube

• Set the intake tube back between the air filter box and throttle body.
• Use the 8mm socket or flat-blade screwdriver to tighten both intake tube clamps.
• Reconnect any breather hose by hand.
• Make sure the intake tube is fully seated with no gaps.

Step 13: Refill the Cooling System

• Use a clean funnel to add OAT coolant premix compatible with Chrysler MS-12106 into the coolant reservoir.
• Fill to the COLD FILL line on the reservoir.
• Leave the reservoir cap off for the initial warm-up.

Step 14: Bleed Air from the Cooling System

• Start the engine and let it idle with the heater set to full hot and the blower on low.
• Watch the coolant level in the reservoir.
• Add coolant with the clean funnel as the level drops.
• Let the engine warm up until the upper radiator hose gets hot, which means the thermostat has opened.
• Squeeze the upper radiator hose gently by hand a few times to help move trapped air.
• Do not put your hands near the belt, fan, or pulleys while the engine is running.

Step 15: Final Coolant Level Check

• Once the engine reaches normal temperature and the heater blows warm air, install the coolant reservoir cap by hand.
• Shut the engine off and let it cool completely.
• Use the clean funnel to top off the coolant to the COLD FILL line if needed.
• Use shop towels to wipe any spilled coolant from the engine bay.

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✅ After Repair

• ✅ Start the engine and check around the thermostat housing and upper radiator hose for leaks.
• 🌡️ Watch the temperature gauge during the first drive. It should rise steadily and stay near normal.
• 🔥 Confirm the cabin heater blows hot air once the engine is warm.
• 🧊 After the first full cool-down, recheck the coolant level and top off if needed.
• ♻️ Dispose of old coolant properly at a recycling or hazardous-waste facility. Do not pour it on the ground or into a drain.

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💰 DIY vs Shop Cost

Shop Cost: $220-$420 (parts + labor)

DIY Cost: $45-$110 (parts only)

You Save: $175-$310 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.5 hours.

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🎯 Ready to get started?

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