🔧 Spark Plugs - Replacement

The 3.5L V6 in your Explorer uses coil-on-plug ignition, so each plug is accessed one cylinder at a time after removing the ignition coils. This is a straightforward job, but clean work matters because dirt in the plug wells can fall into the cylinders.

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

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⚠️ Safety & Precautions

• Let the engine cool fully before starting. Hot aluminum threads can be damaged easily.
• Disconnect the negative battery cable before removing coils to reduce the chance of a misfire or accidental start.
• Keep debris out of the spark plug wells. Clean around each coil before removal.
• Do not overtighten the spark plugs. The cylinder head threads can strip.
• Use care with coil connectors. The plastic locks can break if forced.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 8mm socket
• 5/8" spark plug socket
• 1/4" drive ratchet
• 3" extension
• 6" extension
• Torque wrench
• Flat-blade trim tool
• Needle-nose pliers
• Compressed air
• Safety glasses
• Mechanic gloves

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plug set - Qty: 6

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Let the engine cool down completely.
• Disconnect the negative battery cable using a 10mm socket.
• Work on one cylinder at a time.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove engine cover and intake ducting

• Use a flat-blade trim tool to lift off the engine cover if equipped.
• Use an 8mm socket to loosen the air intake duct clamps.
• Remove any duct or tube that blocks access to the ignition coils.
• Set every clamp aside in order.

Step 2: Disconnect the battery

• Use a 10mm socket to remove the negative battery cable.
• Move the cable aside so it cannot spring back.
• This helps prevent accidental shorts and misfire codes.

Step 3: Remove the ignition coils

• Use an 8mm socket and 1/4" ratchet to remove each coil hold-down bolt.
• Press the connector tab and unplug each coil electrical connector.
• Twist the coil gently, then pull it straight out.
• Do not pry on the coil body.

Step 4: Clean the spark plug wells

• Use compressed air to blow debris away from each plug well.
• Make sure no dirt falls into the cylinder after the plug comes out.
• Clean first, remove second.

Step 5: Remove the old spark plugs

• Use a 5/8" spark plug socket with a 3" or 6" extension to remove each plug.
• Turn slowly and feel for resistance.
• If a plug feels tight, work it back and forth gently rather than forcing it.

Step 6: Install the new spark plugs

• Verify the plugs are correct for your Explorer and do not force the gap if they are pre-gapped.
• Start each plug by hand using the spark plug socket and extension only.
• Tighten each plug with a torque wrench to 15 Nm (11 ft-lbs).
• Hand-start every plug.

Step 7: Reinstall the ignition coils

• Push each coil straight down onto its spark plug until fully seated.
• Reconnect each electrical connector until it clicks.
• Install the coil bolts using an 8mm socket and tighten to 8 Nm (71 in-lbs).

Step 8: Reassemble the intake and engine cover

• Reinstall any intake ducting removed earlier.
• Tighten the duct clamps with an 8mm socket.
• Reinstall the engine cover if equipped.
• Reconnect the negative battery cable with a 10mm socket and tighten snugly.

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✅ After Repair

• Start the engine and let it idle smoothly.
• Listen for misfires, ticking, or vacuum leaks.
• Check the dashboard for a check engine light.
• If the engine runs rough, recheck each coil connector and plug torque.
• Take a short test drive and confirm normal acceleration.

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💰 DIY vs Shop Cost

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

DIY Cost: $70-$180 (parts only)

You Save: $280-$470 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-2.5 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.