🔧 2500 - Thermostat Replacement

Your 2500’s thermostat controls coolant flow to keep engine temperature stable. If it sticks open you may get low heat and poor warm-up; if it sticks closed you can overheat. The job is mostly access + careful coolant handling.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.0 hours

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⚠️ Safety & Precautions

• ⚠️ Never open the coolant cap hot—pressurized coolant can burn you.
• ⚠️ Keep hands/tools away from the fan and belt area.
• ⚠️ Catch all coolant and dispose of it properly (it’s toxic to pets).
• 🔋 Battery disconnect is not required, but keep the key off while working.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Drain pan (at least 3-gallon)
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• 1/4" drive ratchet
• 3/8" drive ratchet
• 3" extension
• 6" extension
• 10mm socket
• 8mm socket
• Flathead screwdriver
• Hose clamp pliers
• Trim clip tool
• Plastic scraper
• Torque wrench (in-lb)
• Shop rags
• Funnel

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Engine thermostat - Qty: 1
• Thermostat seal / O-ring - Qty: 1
• Engine coolant (Mopar OAT 50/50 premix) - Qty: 2-3 gallons
• Upper/lower radiator hose clamp - Qty: 1-2 (optional if originals are weak)

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📋 Before You Begin

• Park on level ground, set the parking brake, and chock the rear wheels.
• Let the engine cool fully (radiator hoses should feel cool).
• Set the HVAC to full heat before you start refilling later (this helps coolant move through the heater circuit).
• If you need more room, raise the front with a floor jack and support it with jack stands.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Relieve pressure safely

• Put on safety glasses and nitrile gloves.
• Slowly loosen the coolant reservoir cap by hand (only when cold) to release any leftover pressure, then remove it.

Step 2: Drain enough coolant to drop the level below the thermostat

• Place a drain pan (at least 3-gallon) under the radiator drain area.
• Open the radiator drain (petcock) using a flathead screwdriver if needed.
• Drain until coolant flow slows, then close the drain.

Step 3: Locate the thermostat housing

• Follow the lower radiator hose by hand (engine off) to where it connects at the front of the engine—this connection point is the thermostat housing/water inlet.
• Tip: Lower hose usually goes to the thermostat.

Step 4: Remove intake ducting for access (if needed)

• Loosen intake tube clamps with an 8mm socket (or use a flathead screwdriver if it’s a screw clamp).
• Release any clips with a trim clip tool and move the intake tube/air ducting out of the way.

Step 5: Disconnect the hose at the thermostat housing

• Move the spring clamp back using hose clamp pliers. (Hose clamp pliers are special pliers that lock onto spring clamps so they don’t slip.)
• Twist the hose gently to break it loose, then pull it off.
• Catch any spill with shop rags and your drain pan.

Step 6: Remove the thermostat housing

• Remove the housing bolts using a 10mm socket with a 3" extension or 6" extension.
• Lift the housing off carefully and remove the thermostat and seal.

Step 7: Clean the mating surfaces

• Use a plastic scraper and shop rags to clean the housing and engine sealing surfaces.
• Do not gouge the aluminum surface.

Step 8: Install the new thermostat and seal

• Install the new thermostat seal / O-ring onto the thermostat (or into the housing—match how the old one was installed).
• Install the thermostat into position.
• If the thermostat has a small bleed/vent, position it at the top (12 o’clock) so air can escape.

Step 9: Reinstall the thermostat housing

• Set the housing in place and hand-thread the bolts to avoid cross-threading.
• Tighten bolts evenly using a 10mm socket.
• Torque to 12 Nm (106 in-lbs) using a torque wrench (in-lb).

Step 10: Reconnect the hose and reassemble

• Push the hose fully onto the housing, then move the clamp back into its original position using hose clamp pliers.
• Reinstall intake ducting and tighten clamps with an 8mm socket.

Step 11: Refill coolant

• Using a funnel, refill with Engine coolant (Mopar OAT 50/50 premix) at the coolant reservoir until it reaches the proper level.
• Leave the cap off for the initial warm-up.

Step 12: Bleed air and verify thermostat operation

• Start the engine and let it idle.
• Set the heater to max heat and medium fan.
• Watch the coolant level and top off as it drops (use your funnel).
• As the engine warms up, the upper radiator hose should get hot when the thermostat opens.
• Once bubbles reduce and the level stabilizes, install the reservoir cap by hand.

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✅ After Repair

• Let the engine reach normal operating temperature, then check for leaks around the thermostat housing and hose connection.
• Shut it off, let it cool fully, and recheck the coolant level; top off if needed.
• Over the next 1–2 drives, recheck coolant level and look for any dried coolant residue (a sign of a small leak).

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💰 DIY vs Shop Cost

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

DIY Cost: $60-$180 (parts only)

You Save: $170-$590 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-3.0 hours.

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🎯 Ready to get started?

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