Timing Chain Service

What is service internal on the timing chain kit in terms of miles or years?

Matt There isn’t a strict factory “mile/year” service interval for the timing chains — they’re intended to be a lifetime item — but in practice you should treat them as a wear item and check/replace them proactively.

Quick summary:

• Inspect from about 80k miles (or sooner if the car is noisy).
• Consider replacement around 100–120k miles, or by about 8–10 years if the car’s older.
• Replace sooner if you get rattling on cold start, cam/crank correlation DTCs, rough running, or metal in the oil.
• Don’t just fit new tensioners alone — it’s usually false economy; replace chains, guides, tensioners and the modified oil jet as a kit.

Useful parts mentioned in other posts:

• Timing chain kit (GM): 55570337 (includes updated tensioner and oil jet)
• Balance chain kit (GM): 55563405
• Z20NET tensioner reference: 12608580

If you want I can recommend a checklist for symptoms to watch for, or help find local shops in Bridlington/Beverley that do the full kit replacement.

Z22SE Bot I thought it was supposed to be 10 years or 100,000 miles?

Matt Short answer: manufacturers usually call the chain “lifetime” (no hard interval), so there isn’t a strict factory 10 years / 100k mile service. People commonly use ~100–120k miles or ~8–10 years as a practical guideline because the guides/tensioners wear by then.

Why that number:

• No official interval — factory says lifetime, but in-service experience shows wear.
• Wear factors — age, miles, oil quality, and cold-starts accelerate guide/tensioner wear.
• Failure signs — rattling on cold start, cam/crank correlation DTCs, rough running or metal in the oil mean replace immediately.

What I’d recommend:

• Inspect from ~80k miles or earlier if noisy.
• Plan full kit replacement around 100–120k miles or ~8–10 years as a precaution.
• Don’t fit tensioners alone — replace chains, guides, tensioners and the updated oil jet as a kit (GM timing chain kit 55570337; balance chain kit 55563405; tensioner ref 12608580).

If you’re under 100k with no symptoms and good oil/service history you can monitor, but don’t ignore any of the failure signs. Want me to suggest a checklist for inspection or local garages in Bridlington/Beverley who’ll do the full kit?