🔧 Spark Plugs - Replacement

Your Silverado’s 4.8L uses 8 spark plugs, one for each cylinder. This job is straightforward, but you need to work carefully so you do not crack a coil connector, strip a plug hole, or cross-thread the new plugs.

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

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⚠️ Safety & Precautions

• Let the engine cool completely before starting. Hot aluminum cylinder heads can damage plugs and threads.
• Disconnect the negative battery cable before removing coils or plug wires.
• Keep dirt out of the spark plug wells. Debris can fall into the cylinder when the plug is removed.
• Do not pull on the plug wires. Grab the boot, not the wire. A boot is the thick rubber end that slips over the plug.
• Do not use compressed air aggressively near open plug holes if debris could blow inside.

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🔧 Required Tools

You'll need the following tools for this repair:

• 3/8-inch drive ratchet
• 5/8-inch spark plug socket
• 3-inch extension
• 6-inch extension
• Torque wrench
• 10mm socket
• Flat blade trim tool
• Pick tool
• Dielectric grease
• Compressed air
• Safety glasses
• Mechanic gloves

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs - Qty: 8

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Let the engine cool fully.
• Disconnect the negative battery cable with 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: Disconnect power

• Use a 10mm socket to remove the negative battery cable.
• Move the cable aside so it cannot spring back and touch the terminal.

Step 2: Access the first bank

• Open the hood and locate the plug wires running from the coils to the plugs.
• If the engine cover or intake duct blocks access, remove it with the appropriate flat blade trim tool or ratchet and socket as needed.
• Labeling wires helps avoid mix-ups.

Step 3: Remove one plug wire and coil connection

• Use your hands and a pick tool if needed to release the connector lock on the coil.
• Pull the plug wire boot straight off the spark plug. Do not yank the wire.
• If equipped with a coil bolt, remove it with a 10mm socket.

Step 4: Clean the plug well

• Use compressed air to blow dirt away from the plug well.
• Make sure no debris falls into the cylinder when the plug is removed.

Step 5: Remove the old spark plug

• Use a 5/8-inch spark plug socket, extension, and ratchet to loosen and remove the plug.
• Turn slowly at first. If it feels stuck, stop and work it back and forth carefully.

Step 6: Install the new spark plug

• Check the new plug gap if it is not pre-gapped.
• Thread the plug in by hand first using the spark plug socket and extension.
• Once seated, use a torque wrench to tighten to 25 Nm (18 ft-lbs).
• Hand-thread first to avoid cross-threading.

Step 7: Reinstall the wire and coil

• Add a small amount of dielectric grease inside the plug boot.
• Push the boot onto the plug until it fully seats.
• Reinstall the coil bolt with a 10mm socket if removed.

Step 8: Repeat for all 8 plugs

• Repeat Steps 3 through 7 for each cylinder, one at a time.
• Keep the plug wires in their original positions.

Step 9: Reconnect power

• Reconnect the negative battery cable using a 10mm socket.
• Make sure the terminal is snug and secure.

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✅ After Repair

• Start the engine and listen for a smooth idle.
• Check that no plug wires are loose.
• If the check engine light is on, scan for misfire codes.
• Take a short test drive and make sure acceleration is smooth.

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💰 DIY vs Shop Cost

Shop Cost: $240-$480 (parts + labor)

DIY Cost: $40-$120 (parts only)

You Save: $200-$360 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?

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