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You are watching: How to change spark plugs on 2004 chevy trailblazer

As this forum gave me so lot in learning about my vehicle, I believed I"d walk ahead and also give other back, and document my brand-new found knowledge and also show friend the measures on just how to adjust your 4.2L I-6 Spark Plugs.Note: typical sense would dictate the you go ahead and do a throttle body clean in conjunction v the spark plug replacement; only 4 bolts and 2 connectors continue to be to remove the throttle body indigenous the manifold, and the effort is well worth the time.Tools Needed:8 mm Socket10 mm SocketRegular flat Blade screwdriver (Optional)3/8" Spark Plug WrenchSocket ExtensionsSupplies Needed:Throttle Body and Carb Cleaner (CRC or Equivalent)Shop RagsAnti-Sieze compound (Loctite or Equivalent)Parts Needed:6 AC-Delco Iridium (PN 41-103) Spark Plugs (As per AC Delco service Bulletin, 103"s room pregapped in ~ manufacturer, and also do not need gapping)InstructionsSpark Plugs room accessed by remove the Resonator / Pre-Plenum (Marked Vortec 4200), located at the height of your engine.


Then, eliminate the Air crate Hose Clamp, making use of an 8 mm socket, or optionally, a regular flat tongue screwdriver.

Next, eliminate the throttle body water tap clamp, using the same socket or screwdriver.

Remove the forward Resonator connect bolt, utilizing a 10 mm socket.

Followed through the aft Resonator attach bolt, with exact same 10 mm socket.
After removing the wire loom clamp located simply aft the the rear Resonator attach bolt, you deserve to now lift and also remove the resonator; please an alert the Crankcase vent hose under the Resonator attached come the valve cover; this just slides off.You will now see the 6 coil package exposed; Cylinders are numbered 1 with 6, v Cylinder 1 situated at the radiator side, Cylinder 6 at the firewall side.
Using slim upward pressure while rocking next to side, pull the coil fill up and also out of the spark plug well, and also lay it come the side.
You have the right to now check out the spark plug in ~ the bottom that the well; using a 3/8 spark plug socket, remove and replace each of the 6 spark plugs. Prior to inserting the brand-new spark plugs, apply anti-seize link to the object of the brand-new plug; this will aid in removal throughout your next plug change.Here’s a picture of the old spark plug (not come bad, considering lock have about 180K miles on them)
As noted; provided you have actually the Resonator / Plenum currently removed, friend really must go ahead and clean her Throttle Body. Accuse on cleaning our throttle body deserve to be uncovered here: note: that is most basic to perform this with Cylinders 3 and also 4 coil package removed; it makes accessing the bottom accelerator body bolts lot easier. Right here is a picture of the manifold side of the throttle body pre-cleaning.

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Just retrace your measures to reassemble; details to remember space to remember to reattach the Crankcase Vent water tap under the Resonator, and also don"t forget your two connectors on her throttle body.Hope this helps any of girlfriend contemplating law the project yourself; with a quote of $130 come $180 native my local dealer to readjust plugs, I conserve myself close come $100 by doing it myself.