🔧 Express 3500 - Water Pump Replacement

The water pump circulates coolant through your engine and radiator. When it leaks or the bearing wears out, you can get coolant loss, overheating, or a squealing/grinding noise. Replacing it restores proper cooling and prevents engine damage.

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

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⚠️ Safety & Precautions

• ⚠️ Work on a cold engine only; hot coolant can cause severe burns.
• ⚠️ Support the van securely if you lift it; never rely on a jack alone.
• ⚠️ Keep hands/tools clear of the fan and belt path.
• ⚠️ Coolant is toxic; catch it in a drain pan and dispose of it properly.
• ⚠️ Do not mix coolant types; this system uses Dex-Cool.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Drain pan (at least 4-gallon)
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• 3/8" drive ratchet
• 1/2" drive breaker bar
• 3/8" drive torque wrench (10-80 ft-lbs)
• 1/2" drive torque wrench (50-250 ft-lbs)
• Socket set (8mm, 10mm, 13mm, 15mm)
• Serpentine belt tool (specialty)
• Fan clutch wrench set, 36mm (specialty)
• Flat-blade screwdriver
• Hose clamp pliers (specialty)
• Trim clip remover
• Plastic gasket scraper
• Shop rags
• Funnel

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Water pump assembly - Qty: 1
• Water pump gaskets (pump-to-block) - Qty: 2
• Thermostat housing gasket/O-ring - Qty: 1
• Dex-Cool coolant (50/50 premix) - Qty: 4-5 gallons
• Serpentine belt - Qty: 1 (recommended if belt is cracked/glazed)
• Upper radiator hose clamp - Qty: 1 (only if old clamp is weak)
• Lower radiator hose clamp - Qty: 1 (only if old clamp is 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 completely (ideally overnight).
• Set the HVAC to HEAT before you start (this helps coolant flow through the heater core during refill).
• Optional but helpful: disconnect the negative battery cable using an 10mm socket to prevent accidental fan/engine cranking.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Drain the coolant

• Place a drain pan (at least 4-gallon) under the radiator drain.
• Open the radiator drain cock by hand or with a flat-blade screwdriver (gentle pressure).
• Remove the coolant reservoir cap to help it drain faster.

Step 2: Remove the radiator fan shroud (if equipped)

• Use a trim clip remover and/or 10mm socket to remove the shroud fasteners.
• Lift the shroud up and back to create room. More room = easier fan removal.

Step 3: Remove the engine cooling fan (mechanical fan setup)

• Use a fan clutch wrench set, 36mm (specialty) to loosen the fan clutch nut.
• Turn the nut counterclockwise to loosen (normal threads).
• Lift the fan and clutch out carefully without hitting the radiator fins.
• Fan clutch wrench = holds pulley while turning nut.

Step 4: Remove the serpentine belt

• Use a serpentine belt tool (specialty) (or a 1/2" drive breaker bar if it fits) to rotate the belt tensioner and release tension.
• Slip the belt off and note the routing before fully removing it. Take a quick photo.

Step 5: Disconnect hoses from the water pump

• Use hose clamp pliers (specialty) to compress the spring clamps and slide them back on the hose.
• Twist the hose gently to break it free, then pull it off.
• Expect more coolant to drain—keep the drain pan under the pump area.

Step 6: Remove the water pump bolts

• Use a 13mm socket with a 3/8" drive ratchet to remove the water pump bolts.
• Keep track of bolt locations (some are different lengths). Lay them out in a pattern on the floor or cardboard.

Step 7: Remove the water pump

• Pull the pump straight forward off the engine.
• If it’s stuck, tap gently with the palm of your hand—do not pry hard against the aluminum surfaces.
• Remove the old pump gaskets and discard them.

Step 8: Clean the gasket surfaces

• Use a plastic gasket scraper to clean the engine sealing surfaces.
• Wipe clean with shop rags until dry and smooth.
• No gouges—aluminum scratches can cause leaks.

Step 9: Install the new water pump and gaskets

• Place the new water pump gaskets onto the pump (or onto the engine) in the correct position.
• Set the new water pump assembly in place.
• Hand-thread all bolts first using your fingers to prevent cross-threading.
• Tighten bolts evenly using a 13mm socket.
• Torque to 30 Nm (22 ft-lbs) using a 3/8" drive torque wrench.

Step 10: Reconnect hoses

• Push hoses fully onto their fittings.
• Use hose clamp pliers (specialty) to move clamps back into their original positions.
• Confirm clamps sit behind the raised bead on the fitting.

Step 11: Reinstall the serpentine belt

• Route the belt correctly around all pulleys.
• Use the serpentine belt tool (specialty) to rotate the tensioner and slide the belt on.
• Visually verify the belt is centered on every pulley groove.

Step 12: Reinstall the fan and shroud

• Install the fan/clutch assembly by hand-threading the nut first.
• Snug it using the fan clutch wrench set, 36mm (specialty) (it will self-tighten more during operation).
• Reinstall the shroud using the 10mm socket and trim clip remover as needed.

Step 13: Refill coolant

• Close the radiator drain cock.
• Use a funnel to fill the system with Dex-Cool coolant (50/50 premix).
• Fill the reservoir to the correct mark.

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✅ After Repair

• Start the engine and let it idle with the reservoir cap off for a few minutes.
• Turn the heat to full hot and confirm you get steady warm air (this helps purge air).
• Watch for leaks at the pump and hose connections.
• As the engine warms up, add coolant as the level drops.
• When the thermostat opens (upper hose gets hot), verify the coolant level stabilizes, then install the reservoir cap.
• After a full cool-down, recheck the reservoir level and top off if needed.

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💰 DIY vs Shop Cost

Shop Cost: $650-$1,050 (parts + labor)

DIY Cost: $140-$320 (parts only)

You Save: $330-$910 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?

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.