🔧 Blazer - Spark Plug Replacement

On your Blazer, the front spark plugs are easy to reach, but the rear bank sits against the firewall and usually requires removing the upper intake manifold to access the coils and plugs. Replacing spark plugs restores smooth idle, power, and fuel economy, and helps prevent misfires.

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

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and damaged threads.
• ⚠️ Disconnect the negative battery cable before unplugging ignition coils.
• ⚠️ Keep dirt out of the intake ports; cover openings immediately.
• ⚠️ Do not use anti-seize on coated spark plug threads unless the plug maker specifies it.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 3/8" drive ratchet
• 3/8" drive torque wrench (10-30 Nm range)
• 1/4" drive ratchet
• 1/4" drive torque wrench (5-15 Nm range)
• 10mm socket (1/4" drive)
• 8mm socket (1/4" drive)
• 13mm socket
• 5/8" spark plug socket (rubber insert or магнит insert)
• 3/8" drive extension set (3", 6", 10")
• 3/8" drive swivel/universal joint
• Flat trim tool
• Pick tool
• Compressed air blow gun
• Shop vacuum
• Clean shop towels
• Painter’s tape and marker

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (iridium, OEM-equivalent) - Qty: 6
• Upper intake manifold gasket set - 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 cable and isolate it so it can’t spring back.
• Label hoses/connectors with painter’s tape as you unplug them. Prevents mix-ups on reassembly.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover and intake duct

• Pull up to remove the engine appearance cover (it’s press-fit).
• Use an 8mm socket to loosen the air intake hose clamps.
• Unclip/unplug any sensors on the duct as needed, then remove the duct.

Step 2: Replace the FRONT bank spark plugs (radiator-side)

• Unplug one ignition coil electrical connector at a time (press the lock tab, then pull). A “coil” is the stick-shaped part that creates spark for the plug.
• Use a 10mm socket to remove the coil retaining bolt.
• Twist the coil boot gently to break it loose, then pull the coil straight up.
• Blow out the plug well with compressed air blow gun so dirt can’t fall into the cylinder.
• Remove the spark plug using a 5/8" spark plug socket with a 3/8" ratchet and the needed extensions.
• Install the new plug by hand first using the spark plug socket/extension (no ratchet) to avoid cross-threading.
• Tighten with a 3/8" torque wrench: Torque to 18 Nm (13 ft-lbs).
• Apply a small dab of dielectric grease inside the coil boot.
• Reinstall the coil and bolt with a 10mm socket: Torque to 10 Nm (89 in-lbs).
• Reconnect the coil connector until it clicks.
• Repeat for the remaining front bank cylinders, one at a time.

Step 3: Remove the upper intake manifold to access the REAR bank (firewall-side)

• Disconnect the electrical connectors and hoses attached to the upper intake manifold (label with tape as you go).
• Use a flat trim tool and pick tool as needed to release hose locks without breaking them.
• Use a 10mm socket to remove the upper intake manifold bolts.
• Lift the manifold up and off carefully.
• Immediately place clean shop towels over the intake openings to prevent anything from falling in.

Step 4: Replace the REAR bank spark plugs (firewall-side)

• Remove each rear bank coil the same way as the front: unplug, then use a 10mm socket to remove the coil bolt, then pull the coil out.
• Blow out each plug well using the compressed air blow gun.
• Remove and replace each plug using the 5/8" spark plug socket, extensions, and a swivel/universal joint as needed.
• Tighten each new plug with a 3/8" torque wrench: Torque to 18 Nm (13 ft-lbs).
• Reinstall coils and tighten the coil bolts: Torque to 10 Nm (89 in-lbs).

Step 5: Reinstall the upper intake manifold

• Remove the shop towels and inspect to confirm nothing fell into the intake.
• Install the new upper intake manifold gaskets (or replace any that are flattened/torn).
• Set the manifold back into place without pinching any wiring or hoses.
• Hand-start all bolts, then tighten evenly using a 10mm socket.
• Tighten with a 1/4" torque wrench: Torque to 10 Nm (89 in-lbs).
• Reconnect every hose and electrical connector you labeled.

Step 6: Reinstall intake duct and engine cover

• Reinstall the intake duct and tighten the clamps using an 8mm socket.
• Reinstall the engine cover by aligning the grommets and pressing down firmly.
• Reconnect the negative battery cable using a 10mm socket.

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✅ After Repair

• Start the engine and let it idle for 1-2 minutes; it should run smooth with no flashing check engine light.
• Listen for vacuum leaks (hissing) around the upper intake manifold area.
• If you get a misfire code afterward, recheck coil connectors and that each coil is fully seated on the plug.
• Take a short test drive, then recheck for any stored codes if you have a scan tool.

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💰 DIY vs Shop Cost

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

DIY Cost: $70-$160 (parts only)

You Save: $280-$490 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2.0-3.5 hours.

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🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.