🔧 QX60 - Spark Plug Replacement

On your QX60, the front 3 spark plugs are easy to reach, but the rear 3 sit under the upper intake manifold (plenum), so you’ll remove the intake ducting and plenum to access them. Replacing worn plugs restores smooth idle, fuel economy, and helps prevent misfires and catalytic converter damage.

Difficulty Level: Intermediate | Estimated Time: 2.5-4.5 hours

Assumption: Factory V6 layout with rear plugs under the plenum.

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and stripped threads.
• ⚠️ Disconnect the negative battery terminal to prevent accidental shorts.
• ⚠️ Keep dirt out of the intake ports; cover openings immediately.
• ⚠️ Do not over-tighten spark plugs; aluminum heads strip easily.
• ⚠️ Use only a torque wrench for final tightening.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 3/8" drive ratchet
• 1/4" drive ratchet
• 3/8" drive torque wrench (10-40 ft-lbs range)
• 1/4" drive torque wrench (in-lb range)
• 5/8" spark plug socket (rubber insert or magnetic)
• 3/8" drive extension set (3", 6", 10")
• 3/8" drive wobble extension
• 3/8" drive universal joint
• 10mm socket
• 12mm socket
• 8mm socket
• Phillips screwdriver
• Flathead screwdriver
• Trim clip removal tool
• Needle-nose pliers
• Pick tool
• Compressed air blow gun
• Shop vacuum
• Clean shop rags
• Painter’s tape and marker
• Flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (OEM-type) - Qty: 6
• Upper intake manifold (plenum) gasket set - Qty: 1
• Throttle body gasket - Qty: 1
• Dielectric grease - Qty: 1
• Brake cleaner or throttle body safe cleaner - 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 (at least 1-2 hours after driving).
• Disconnect the negative battery cable using a 10mm socket and isolate it so it can’t spring back.
• Use painter’s tape and marker to label any vacuum hoses and connectors you unplug (this prevents mix-ups).
• Have clean shop rags ready to plug intake openings as soon as the plenum comes off.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Pull up on the cover (some are grommet-mounted) or remove fasteners using a 10mm socket.
• Set the cover aside.

Step 2: Remove the air intake duct

• Loosen the hose clamps using an 8mm socket or flathead screwdriver.
• Unplug the intake sensor connector(s) using a pick tool to gently lift the lock tab if needed.
• Remove the duct and set it aside.
• Tip: Don’t yank connectors; unlock them first.

Step 3: Unplug and label plenum-area connectors and vacuum lines

• Use painter’s tape and marker to label hoses before removal.
• Use needle-nose pliers to slide spring clamps back on vacuum hoses.
• Unplug any electrical connectors on/near the throttle body and plenum.

Step 4: Remove (or move) the throttle body

• Unplug the throttle body connector by hand; use a pick tool only if the lock is stubborn.
• Remove throttle body bolts using a 10mm socket.
• Lift the throttle body off and remove the old gasket.
• Cover the opening with a clean shop rag.
• When reinstalling later: Torque to 10 Nm (7 ft-lbs).
• Tip: Don’t push on the throttle plate.

Step 5: Remove the upper intake manifold (plenum)

• Double-check that all hoses and connectors to the plenum are disconnected.
• Remove plenum mounting bolts using a 10mm socket (and a 12mm socket if your bracket hardware uses it).
• Lift the plenum straight up and off.
• Immediately stuff each exposed intake port with a clean shop rag so nothing can fall in.
• Remove and discard the old plenum gaskets.
• When reinstalling later: Torque plenum bolts to 25 Nm (18 ft-lbs).

Step 6: Access the ignition coils

• You will see one ignition coil per cylinder (6 total). An ignition coil is the “stick” that plugs into the spark plug.
• Unplug each coil connector by hand.
• Remove each coil hold-down bolt using a 10mm socket.
• Pull the coil straight up and out. If it’s stuck, twist gently while pulling.
• When reinstalling later: Torque coil bolts to 7.2 Nm (64 in-lbs).

Step 7: Clean the spark plug wells

• Before removing plugs, blow out each spark plug well using a compressed air blow gun.
• Use a shop vacuum to catch loosened debris if needed.
• Tip: Dirt in the cylinder can damage the engine.

Step 8: Remove the old spark plugs

• Use a 5/8" spark plug socket with a 3/8" drive extension and 3/8" drive ratchet to loosen each plug.
• Turn counter-clockwise until fully removed, then lift out carefully.
• If one feels extremely tight, stop and work it back and forth gently to reduce thread damage risk.

Step 9: Install the new spark plugs

• Check each new plug for damage. Do not change the factory gap unless the plug maker specifically instructs it.
• Thread each plug in by hand first using the 5/8" spark plug socket and an extension (no ratchet at first) to avoid cross-threading.
• Final tighten using a 3/8" drive torque wrench: Torque to 25 Nm (18 ft-lbs).
• Tip: Hand-threading prevents expensive head damage.

Step 10: Reinstall ignition coils

• Apply a tiny amount of dielectric grease inside each coil boot (dielectric grease helps prevent moisture and makes future removal easier).
• Push each coil straight onto its plug until fully seated.
• Install coil bolts using a 10mm socket, then torque to 7.2 Nm (64 in-lbs).
• Reconnect each coil electrical connector.

Step 11: Reinstall the plenum with new gaskets

• Remove the clean shop rags from the intake ports.
• Place the new plenum gaskets correctly on the lower intake.
• Set the plenum in place carefully.
• Install bolts finger-tight first, then tighten evenly using a 10mm socket.
• Final tighten with a 3/8" drive torque wrench: Torque to 25 Nm (18 ft-lbs).

Step 12: Reinstall the throttle body and intake duct

• Install a new throttle body gasket, then reinstall the throttle body using a 10mm socket.
• Final tighten: Torque to 10 Nm (7 ft-lbs).
• Reconnect the throttle body connector.
• Reconnect all vacuum hoses and electrical connectors you labeled.
• Reinstall the intake duct and tighten clamps using an 8mm socket or flathead screwdriver.

Step 13: Reconnect the battery and reinstall the engine cover

• Reconnect the negative battery terminal using a 10mm socket.
• Reinstall the engine cover.

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✅ After Repair

• Start the engine and let it idle for 2-3 minutes. It may idle slightly rough for a short time after battery disconnect.
• Listen for hissing (vacuum leak) around the plenum and intake duct.
• Check that the check engine light stays off.
• If idle is unstable after warm-up, perform an idle relearn with a capable scan tool (a scan tool can command the idle learning procedure).
• Do a short test drive, then re-check for any loose clamps or fuel/air smells.

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💰 DIY vs Shop Cost

Shop Cost: $450-$900 (parts + labor)

DIY Cost: $90-$220 (parts only)

You Save: $360-$680 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2.5-4.5 hours.

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