🔧 Spark Plugs - Replacement

Your F-150 uses eight spark plugs, one per cylinder. This job is straightforward, but access is tight on a V8 and the plugs should be swapped carefully to avoid damaging the aluminum cylinder heads.

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

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⚠️ Safety & Precautions

• Work on a cold engine only. Hot aluminum threads can strip easily.
• Disconnect the negative battery cable before starting. This helps prevent accidental starts and protects ignition components.
• Keep dirt out of the spark plug wells. Blow debris out before removing plugs.
• Do not use power tools to install spark plugs. Hand-start every plug to prevent cross-threading.
• Use a torque wrench. Overtightening can damage the cylinder head.

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🔧 Required Tools

You'll need the following tools for this repair:

• 8mm socket
• 10mm socket
• 1/4-inch ratchet
• 3/8-inch torque wrench
• 6-inch extension
• 8-inch extension
• 5/8-inch spark plug socket
• Spark plug gap tool
• Dielectric grease
• Compressed air
• Trim removal tool
• Safety glasses
• Mechanic gloves

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plug set - Qty: 8

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Let the engine cool fully.
• Open the hood and remove the engine cover if equipped.
• Disconnect the negative battery cable using the 10mm socket.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove engine cover and intake ducting

• Use the trim removal tool and 8mm socket to remove the engine cover and any intake tube pieces blocking access to the coil packs.
• Set all fasteners aside in order.

Step 2: Disconnect ignition coil connectors

• Use your fingers to release each coil electrical connector.
• Press the lock tab first, then pull straight off.
• Do not pry on the wires.

Step 3: Remove ignition coils

• Use the 8mm socket and 1/4-inch ratchet to remove each coil hold-down bolt.
• Twist each coil gently, then pull it straight up.
• Inspect the boots for oil, cracks, or burning.

Step 4: Clean the spark plug wells

• Use compressed air to blow dirt away from each plug well.
• This keeps debris from falling into the cylinder when the plug comes out.

Step 5: Remove the old spark plugs

• Use the 5/8-inch spark plug socket, 6-inch extension, and 1/4-inch ratchet to loosen each plug.
• Turn slowly and keep the socket straight.
• If a plug feels stuck, work it back and forth gently.

Step 6: Check and set the new plug gap

• Use the spark plug gap tool to verify the gap on each new plug.
• Set the gap only if needed. Some plugs come pre-gapped, but always check them.
• Check every plug before install.

Step 7: Install the new spark plugs

• Thread each plug in by hand first using the 5/8-inch spark plug socket and extension.
• If a plug does not turn easily, stop and back it out.
• Tighten each plug with the 3/8-inch torque wrench to 18 Nm (13 ft-lbs).

Step 8: Reinstall ignition coils

• Apply a small amount of dielectric grease inside each coil boot.
• Push each coil fully onto its plug.
• Install the coil bolts with the 8mm socket and tighten to 8 Nm (71 in-lbs).
• Reconnect each coil electrical connector until it clicks.

Step 9: Reassemble intake parts and cover

• Reinstall any intake ducting, brackets, and the engine cover using the 8mm socket and trim removal tool.
• Reconnect the negative battery cable with the 10mm socket.

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✅ After Repair

• Start the engine and listen for a smooth idle.
• Check for a flashing check-engine light or misfire.
• If the engine runs rough, recheck coil connectors and plug torque.
• Take a short test drive and confirm normal power delivery.

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💰 DIY vs Shop Cost

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

DIY Cost: $80-$220 (parts only)

You Save: $270-$430 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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