🔧 Cherokee - Spark Plug Replacement

On your Cherokee’s 3.2L V6, you’ll replace 6 spark plugs (one per cylinder). The front bank is straightforward; the rear bank is tight and is typically accessed by removing the upper intake manifold so you can safely remove the coils and plugs.

Difficulty Level: Intermediate | Estimated Time: 2.5-4.0 hours

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⚠️ Safety & Precautions

• ⚠️ Let the engine cool fully before starting (hot aluminum threads can be damaged).
• ⚠️ Disconnect the negative battery cable before unplugging coils/sensors.
• ⚠️ Cover the intake ports as soon as the intake is lifted so nothing can fall inside.
• ⚠️ Use a torque wrench on spark plugs—over-tightening can strip the cylinder head.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 10mm wrench
• 1/4" drive ratchet
• 3/8" drive ratchet
• 8mm socket
• 10mm socket
• 5/8" spark plug socket
• 6" extension (3/8")
• 12" extension (3/8")
• Universal joint wobble adapter (3/8")
• 3/8" torque wrench (10–30 ft-lbs range)
• 1/4" torque wrench (50–200 in-lbs range)
• Flat trim tool
• Pick tool
• Compressed air blow gun
• Shop towels
• Flashlight
• Dielectric grease

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (OE-spec iridium) - Qty: 6
• Upper intake manifold gasket set - Qty: 1
• Throttle body gasket - 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 wait until the engine is completely cool to the touch.
• Disconnect the negative battery cable using a 10mm wrench.
• Lay out 6 new plugs and keep parts from each cylinder together. One cylinder at a time avoids mix-ups.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Pull upward on the engine cover to pop it off the rubber mounts.
• If it’s stuck, gently pry upward with a flat trim tool.

Step 2: Remove the air intake tube (for access)

• Loosen the intake clamps using an 8mm socket and a 1/4" drive ratchet.
• Unplug any sensor connector(s) on the tube using a pick tool to lift the lock tab.
• Remove the intake tube and set it aside.

Step 3: Disconnect throttle body and intake electrical connectors

• Unplug the throttle body connector using a pick tool to release the red/secondary lock (if equipped), then press the release and pull off.
• Unplug the intake sensor connectors you can see on/near the upper intake using a pick tool.

Step 4: Remove the throttle body

• Remove the throttle body bolts using a 10mm socket and a 1/4" drive ratchet.
• Remove the throttle body and old gasket; wipe the sealing surface with shop towels.
• Set the throttle body on a clean towel (don’t drop it).

Step 5: Remove the upper intake manifold

• Disconnect vacuum/PCV hoses from the upper intake by hand; use a flat trim tool only if needed.
• Remove the upper intake bolts using a 10mm socket and a 3/8" drive ratchet.
• Lift the upper intake manifold off.
• Immediately cover the intake ports with shop towels.

Step 6: Remove an ignition coil

• Pick one cylinder to start with.
• Unplug the coil connector using a pick tool.
• Remove the coil retaining bolt using a 10mm socket.
• Twist the coil slightly and pull it straight up to remove.
• Ignition coil bolt: Torque to 9 Nm (80 in-lbs)

Step 7: Remove the old spark plug

• Blow out the spark plug well using a compressed air blow gun so grit doesn’t fall into the cylinder.
• Remove the spark plug using a 5/8" spark plug socket, 12" extension (3/8"), and a 3/8" drive ratchet.
• If it feels stuck, stop and work it back and forth gently. Forcing can strip threads.

Step 8: Install the new spark plug

• Place the new plug in the 5/8" spark plug socket (the rubber insert holds it).
• Thread it in by hand using only the extension (no ratchet) until it seats.
• Tighten with a 3/8" torque wrench: Torque to 18 Nm (13 ft-lbs)
• Put a small dab of dielectric grease inside the coil boot (dielectric grease is a non-conductive silicone grease that helps keep moisture out and makes removal easier).

Step 9: Reinstall the ignition coil

• Push the coil down until it fully seats on the plug.
• Install the coil bolt with a 10mm socket, then torque with a 1/4" torque wrench: Torque to 9 Nm (80 in-lbs)
• Reconnect the coil connector until it clicks.

Step 10: Repeat for the remaining 5 cylinders

• Repeat Steps 6–9 for each cylinder.
• Use the universal joint wobble adapter (3/8") with your extension for the tight rear-bank angles.

Step 11: Reinstall the upper intake manifold with new gaskets

• Remove the shop towels from the intake ports.
• Install the new upper intake manifold gaskets in their grooves.
• Set the upper intake manifold in place and start all bolts by hand.
• Tighten bolts evenly with a 10mm socket, then final torque with a 1/4" torque wrench: Torque to 12 Nm (105 in-lbs)

Step 12: Reinstall the throttle body

• Install a new throttle body gasket.
• Install throttle body bolts using a 10mm socket, then torque with a 1/4" torque wrench: Torque to 12 Nm (105 in-lbs)
• Reconnect the throttle body electrical connector by hand until it clicks.

Step 13: Reinstall the intake tube and engine cover

• Reinstall the intake tube and tighten clamps using an 8mm socket.
• Reconnect any intake tube sensor connectors by hand until they click.
• Press the engine cover back onto its mounts.

Step 14: Reconnect the battery

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

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✅ After Repair

• Start the engine and let it idle 1–2 minutes.
• If the idle is rough or you hear a whistle/hiss, shut it off and recheck intake seals, hoses, and connectors.
• Take a short test drive, then recheck for warning lights.

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💰 DIY vs Shop Cost

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

DIY Cost: $60-$160 (parts only)

You Save: $290-$490 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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🎯 Ready to get started?

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