Autopapyrus · Chevrolet TrailBlazer (2nd generation, 2012)
https://autopapyrus.com/guides/chevrolet/trailblazer/camshaft-replacement/

Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Chevrolet TrailBlazer (2nd generation, 2012): Camshaft Replacement

Replacing the camshafts on this SUV requires removing the valve cover and the timing drive, and on diesel versions also the components covering the cylinder head. The exact procedure and torque values depend on the engine (gasoline or Duramax diesel), and for your configuration they are not documented in publicly available service materials. Below is the general procedure. Check all torque values against the manufacturer's specifications for your engine.

Difficulty: Hard Time: 8-14 hours (depends on the engine and the condition of the timing drive) Steps: 14 Tools: torque wrench, socket and box-end wrench set, timing locking tool set (pins) for setting cam timing and locking the camshafts, gear and sprocket puller, flywheel holder, assembly lube, gasket sealant for mating surfaces, containers for draining oil and coolant, marker and bags for sorting parts

Part

🔩 intake and exhaust camshafts (set for your engine), camshaft and crankshaft seals, valve cover gasket, timing drive kit (chain/belt, tensioners, guides, rollers), cylinder head bolts and camshaft and gear mounting bolts if the manufacturer specifies them as single-use, engine oil and filter, coolant. Camshaft set pricing depends on the engine, so check with your parts supplier

There's a full repair manual for this car Every system, wiring diagrams and torque specs — not just this job. Haynes AutoFix (online). See manuals →

Step by step

14 steps

Determine the reason for replacement: cam lobe wear (scoring, pitting), lifter or tappet noise, or low oil pressure. Inspecting the camshafts and bearing journals often shows that the lifters or hydraulic lash adjusters need replacing too. Replace them together with the camshafts.
Shut off the engine, let it cool, and disconnect the negative battery terminal. Drain the oil and, if necessary, part of the coolant.
Remove everything that blocks access to the valve cover: air ducts, intercooler pipes (on the diesel), engine cover, wiring harnesses, ignition coils or injector lines, and crankcase ventilation. Label and photograph the connectors and hoses.
Set the crankshaft to TDC on cylinder 1 using the marks. Lock the cam timing with the special locking tools, and before disassembly mark the position of the chain or belt relative to the gears with paint.
Remove the valve cover, first loosening the bolts in a crisscross pattern over several passes.
Release the timing drive tensioner and remove the camshaft gears (on chain-driven engines, keep the chain from falling into the crankcase by tying it up with wire). Loosen the gear bolts while holding the camshaft by its hex section or flats.
Remove the camshaft bearing caps. They are numbered and directional, so lay them out in order. Loosen them evenly, in several passes, from the outside toward the center so the camshaft does not bind or warp.
Lift out the camshafts and check the bearing journals in the head for scoring. Measure the bearing clearances according to the specifications. If the journals are worn, the cylinder head must be repaired or replaced, not just the camshafts.
Lubricate the new camshafts and journals with assembly lube and clean engine oil. Lay the camshafts in place according to the marks, install the caps in their original positions, and tighten them evenly in several passes to the specified torque (look up the value for your engine, and do not tighten by feel).
Install new camshaft seals, fit the gears, set the timing using the locking tools and marks, and tension the timing drive according to the specifications. Replace the chain, tensioner, and guides if they show wear.
Remove the locking tools, turn the crankshaft by hand through two full revolutions, and make sure the marks line up again and the engine turns without binding or skipping.
Apply sealant to the joints indicated in the specifications, install a new valve cover gasket, and tighten the bolts in a crisscross pattern to a low torque (usually just a few N·m, with the exact value per the specifications).
Reassemble everything you removed, add fresh oil and a new filter, and top off the coolant. Before the first start, prime the oil system by cranking the engine with the starter with the fuel supply disabled, if the manufacturer allows it.
Start the engine and let it run, then check oil pressure, leaks, and that there are no error codes. After 500-1,000 km (300-600 miles), check the oil level and the valve cover bolt torque.

Common mistakes and warnings

A mistake in setting the cam timing on this engine can cause the valves to hit the pistons, leading to costly repairs. If you do not have experience with timing work and a set of locking tools, do not attempt this job yourself. Take it to a repair shop. The engine is not specified in the guide, so before buying parts, confirm which engine is in your vehicle (the marking on the block and in the vehicle documents). Camshafts for different versions are not interchangeable.