Holden Commodore V6 Timing Chain Rattle and Stretch (Australia)

The 3.6-litre Alloytec V6 was fitted to a huge number of VZ and VE Commodores, as well as Calais, Statesman, Caprice and Ute models. It's a smooth engine, but it's well known for timing chain stretch, especially in early VE models. The timing chains keep the camshafts in step with the crankshaft. When they stretch, the timing drifts, the engine computer notices, and you get a check-engine light and, often, a rattle.

If you'd like a ranked list of likely causes for your exact Commodore and symptoms, the DIY Mechanic app can work through it with you. The basics are below.

What causes Commodore timing chain stretch?

In January 2006, Holden changed the Alloytec's timing chains from a roller type to a narrower inverted-tooth design. According to a GM service bulletin, some of the new chains, built into engines from early 2006 to around May 2007, were made with links that didn't meet specification and could elongate. Later engines can stretch their chains too, and missed oil changes, the wrong oil and long service intervals are widely blamed for making it worse. Not every Commodore has the problem, but it's common enough that it's the first thing many mechanics check on a V6 with a check-engine light.

What are the signs of a stretched timing chain?

• Check-engine light: the most common first sign, often before any noise.
• Fault codes P0008, P0009, P0016, P0017, P0018 or P0019: these point to the camshafts and crankshaft being out of alignment.
• Rattle at start-up: a rattle or chatter from the front of the engine for a few seconds after a cold start that gets longer over time.
• Rough idle or hesitation: as the timing drifts further, the engine can run less smoothly.
• Loss of power and fuel economy: the engine can't run efficiently with incorrect cam timing.

Commodore V6 symptoms and what they usually point to

Can I keep driving with a stretched timing chain?

It's not a good idea for long. Early stretch might only cause a warning light, but chains keep wearing, and if a chain jumps a tooth or fails, the valves and pistons can collide, causing serious engine damage that often costs more than the car is worth. If you have timing-related codes or a rattle that's getting worse, keep driving to a minimum and get a quote.

How much does it cost to fix?

The repair involves replacing the timing chains and, usually, the guides and tensioners. It's a big job on this engine, and pricing commonly runs into the thousands depending on the workshop, parts used and what else needs doing while it's apart. Get a written quote, ask what's included, and ask whether they've done this job on an Alloytec before, since experience counts on this engine.

When should I see a mechanic?

Have the code read as soon as the check-engine light comes on, and book an inspection if you hear a rattle. A mechanic can check cam timing data with a scan tool to confirm whether the chains have stretched before anything is pulled apart. Keeping up with oil changes using the correct oil is the best way to look after the chains you have.

To work out the most likely cause for your Commodore before you book it in, start a free diagnosis preview below.