🔧 Traverse - Spark Plug Replacement

On your Traverse’s 3.6L V6, the front 3 spark plugs are easy to reach, but the rear 3 sit under the upper intake manifold (the plastic/aluminum “air runner” on top of the engine). You’ll replace all 6 plugs, remove the ignition coils, and (for the rear bank) lift the upper intake to access the plugs.

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

Assumption: Factory-style 3.6L V6 with coil-on-plug; rear bank requires upper intake removal.

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and to protect aluminum threads.
• ⚠️ Disconnect the negative battery cable before unplugging throttle body/engine sensors.
• ⚠️ Keep dirt out of the intake ports—cover openings with clean rags as soon as the intake is lifted.
• ⚠️ Do not over-tighten spark plugs; the cylinder heads are aluminum.
• ⚠️ Do not use anti-seize on modern plated spark plug threads unless the plug maker specifically says to.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Scan tool (OBD-II) (specialty)
• 10mm socket
• 8mm socket
• Ratchet (3/8")
• Extension set (3/8")
• Wobble extension (3/8")
• Torque wrench (3/8", 5–80 Nm range)
• Spark plug socket 5/8" (16mm) with rubber insert
• Flat trim tool
• Needle-nose pliers
• Compressed air blow gun
• Shop vacuum
• Clean shop rags
• Small flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (OEM-spec, iridium/platinum) - Qty: 6
• Upper intake manifold gasket set - Qty: 1
• Throttle body gasket - Qty: 1
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Open the hood and let the engine cool completely.
• Use a 10mm socket to disconnect the negative battery terminal and tuck it aside so it can’t spring back.
• Have clean rags ready to plug intake openings once the upper intake is removed.
• A wobble extension helps reach tight bolts. (It’s an extension with a slightly flexible head.)

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover and intake ducting

• Pull up on the engine cover to pop it off (some are retained by rubber grommets). Use a flat trim tool if needed.
• Loosen the air duct clamps using an 8mm socket.
• Disconnect any small breather/PCV hoses with needle-nose pliers (squeeze the clamp, slide it back, then twist the hose off gently).
• Remove the air duct and set it aside.

Step 2: Label and unplug coil connectors (front bank first)

• On the front bank (radiator side), locate the three ignition coils (one per cylinder).
• Unplug each coil electrical connector by lifting the lock tab (if equipped) and pulling the connector straight off by hand.
• Don’t pull on the wires—pull the connector body.

Step 3: Remove the front ignition coils

• Remove each coil retaining bolt using a 10mm socket.
• Pull the coil straight upward to remove it from the spark plug tube.
• Set coils in order so they go back to the same cylinder.

Step 4: Remove the front spark plugs

• Blow out the spark plug wells using a compressed air blow gun so dirt doesn’t fall into the engine.
• Remove each spark plug using a spark plug socket 5/8" (16mm), a ratchet (3/8"), and a 3/8" extension.
• If a plug feels stuck, tighten slightly then loosen again. Avoid forcing it.

Step 5: Install the new front spark plugs

• Start each new spark plug by hand using the spark plug socket 5/8" (16mm) and an extension (3/8") (no ratchet at first) to prevent cross-threading.
• Once seated, tighten with a torque wrench (3/8"): Torque to 18 Nm (13 ft-lbs).
• Apply a small dab of dielectric grease inside each coil boot (the rubber end). (Dielectric grease helps prevent moisture/corrosion.)

Step 6: Reinstall the front coils

• Push each coil straight down until fully seated on the plug.
• Install coil bolts with a 10mm socket, then tighten with a torque wrench (3/8"): Torque to 10 Nm (89 in-lbs).
• Reconnect coil electrical connectors until they click.

Step 7: Remove components needed to lift the upper intake (rear bank access)

• Unplug the throttle body connector and any sensor connectors attached to the upper intake using your hands (use a flat trim tool gently if a lock tab is stubborn).
• Disconnect vacuum/PCV hoses from the upper intake using needle-nose pliers for spring clamps.
• Remove the throttle body fasteners using a 10mm socket and set the throttle body aside carefully.
• Remove the upper intake manifold bolts using a 10mm socket, extensions (3/8"), and a wobble extension (3/8") as needed.

Step 8: Lift the upper intake and protect the engine

• Lift the upper intake straight up and off (it may need a gentle wiggle).
• Immediately cover the exposed intake ports with clean shop rags to keep bolts/dirt out.
• Remove the old intake gaskets and wipe the sealing surfaces clean with a clean shop rag.

Step 9: Remove the rear coils and rear spark plugs

• Remove rear bank coil bolts using a 10mm socket, then pull coils upward to remove.
• Blow out the plug wells using a compressed air blow gun.
• Remove the rear spark plugs using the spark plug socket 5/8" (16mm), ratchet (3/8"), and extensions (3/8").

Step 10: Install the new rear spark plugs and reinstall rear coils

• Start plugs by hand first using the spark plug socket 5/8" (16mm) and extension (3/8").
• Tighten with a torque wrench (3/8"): Torque to 18 Nm (13 ft-lbs).
• Add a small dab of dielectric grease inside each coil boot.
• Reinstall coils and tighten coil bolts: Torque to 10 Nm (89 in-lbs) using a torque wrench (3/8").
• Reconnect coil connectors until they click.

Step 11: Reinstall the upper intake manifold and throttle body

• Install new upper intake manifold gaskets into the intake (make sure they sit flat and fully seated).
• Remove the rags from the intake ports.
• Set the upper intake back in place carefully (don’t pinch wiring or hoses).
• Install intake bolts finger-tight using a 10mm socket, then tighten evenly in a crisscross pattern with a torque wrench (3/8"): Torque to 10 Nm (89 in-lbs).
• Install a new throttle body gasket, reinstall the throttle body using a 10mm socket, then tighten with a torque wrench (3/8"): Torque to 10 Nm (89 in-lbs).
• Reconnect throttle body/sensor connectors and all vacuum/PCV hoses.

Step 12: Reinstall the intake duct and engine cover

• Reinstall the air intake duct and tighten clamps using an 8mm socket.
• Reconnect any breather hoses using needle-nose pliers to reposition clamps.
• Reinstall the engine cover by pressing it down onto its grommets.

Step 13: Reconnect battery

• Reconnect the negative battery cable using a 10mm socket.

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✅ After Repair

• Start the engine and let it idle for 2–3 minutes. A slightly rough idle for the first few seconds can be normal after reconnecting the battery/throttle body.
• Listen for hissing (vacuum leak). If you hear one, recheck every hose and the intake seating.
• Use a scan tool (OBD-II) to check for stored codes and clear any that were set during unplugging.
• Road test: light acceleration first, then normal driving. Make sure there’s no misfire, flashing check engine light, or fuel smell.

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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 2.5–4.0 hours.

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