🔧 Expedition - Spark Plug Replacement

Replacing spark plugs restores strong ignition, smooth idle, and fuel economy. On your Expedition’s 3.5L turbo engine, plugs wear faster than non-turbo engines, so fresh plugs help prevent misfires under boost.

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

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and stripped threads.
• ⚠️ Keep dirt out of the spark plug holes; debris can damage the engine.
• ⚠️ Do not use anti-seize on modern plated spark plug threads unless the plug maker specifically says to.
• ⚠️ If you disconnect the battery, use a 10mm socket and remove the negative terminal first.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 1/4" drive ratchet
• 3/8" drive ratchet
• 3/8" drive torque wrench (50-250 in-lb range)
• 7mm socket
• 8mm socket
• 10mm socket
• 5/8" spark plug socket
• 3/8" drive extension set (3", 6", 12")
• 3/8" drive universal joint swivel
• Trim clip removal tool
• Flathead screwdriver
• Compressed air blow gun
• Feeler gauge set
• Small pick tool
• Flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (OEM-spec for 3.5L turbo) - Qty: 6
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Let the engine cool completely (cold to the touch).
• Pop the hood and remove loose items from the engine bay.
• Tip: Take a quick photo of hose routing.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Lift the engine cover straight up (it’s held by rubber grommets).
• Use a flashlight to locate all six ignition coils (one per cylinder).

Step 2: Create working room at the front bank (easy side)

• If the air inlet tube blocks access, loosen the clamp(s) with a flathead screwdriver or 7mm socket and move the tube aside.
• Use an 8mm socket or 10mm socket to remove any small brackets that limit access (set bolts aside in a tray).

Step 3: Unplug and remove one ignition coil

• Work one cylinder at a time so parts don’t get mixed up.
• Press the coil connector tab and unplug it. If it’s stubborn, use a small pick tool gently (do not break the tab).
• Remove the coil hold-down bolt with an 8mm socket.
• Twist the coil boot slightly, then pull the coil straight up and out.
• Ignition coil = the “stick” that snaps onto the plug.

Step 4: Clean the spark plug well

• Blow out the plug hole using a compressed air blow gun so dirt can’t fall into the cylinder.

Step 5: Remove the old spark plug

• Use a 5/8" spark plug socket, 3/8" drive extension, and 3/8" drive ratchet to loosen and remove the plug.
• If it feels extremely tight, stop and re-check that the engine is cold.

Step 6: Check and prepare the new spark plug

• Verify the new plug gap using a feeler gauge set. (Many OEM-style plugs come pre-gapped, but you still verify.)
• Do not apply anti-seize unless the plug manufacturer instructs it.
• Put a tiny smear of dielectric grease inside the coil boot (not on the plug threads).
• Dielectric grease helps prevent moisture and sticking.

Step 7: Install the new spark plug (don’t cross-thread)

• Place the new plug into the 5/8" spark plug socket.
• Start threading it by hand using only the extension (no ratchet at first). It should spin in smoothly.
• Once seated, tighten with a 3/8" drive torque wrench to Torque to 15 Nm (133 in-lb).

Step 8: Reinstall the ignition coil

• Push the coil straight down until it fully seats on the plug.
• Install the coil bolt using an 8mm socket, then torque with a 3/8" drive torque wrench to Torque to 5 Nm (44 in-lb).
• Reconnect the electrical connector until it clicks.

Step 9: Repeat for the remaining 5 cylinders (rear bank is tighter)

• Use a 3/8" drive universal joint swivel plus 6" and 12" extensions to access the rear bank plugs.
• If a plastic cowl/trim panel limits access, remove push-pins with a trim clip removal tool to gain room.
• Tip: Go slow; tight access is normal.

Step 10: Reassemble the intake tube and engine cover

• Reinstall any brackets with an 8mm socket or 10mm socket.
• Reinstall the air inlet tube and tighten clamps with a 7mm socket or flathead screwdriver.
• Press the engine cover back onto its grommets.

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✅ After Repair

• Start the engine and listen for a smooth idle (no shaking).
• If the check engine light comes on or it runs rough, re-check that every coil connector is fully clicked in.
• Test drive for 10 minutes with light acceleration first, then moderate acceleration.
• Re-check that the intake tube clamps are snug (no hissing/boost leak sounds).

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💰 DIY vs Shop Cost

Shop Cost: $350-$700 (parts + labor)

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

You Save: $170-$640 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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