What mileage do you replace timing chain on 2004 Chevy classic?

There's no set mileage interval for replacing a timing chain on a 2004 Chevy Classic (which used either a 2.2L Ecotec or a 3.5L V6). Unlike timing belts which have a recommended replacement interval (usually around 100,000 miles), timing chains are designed for much longer life and are often considered "lifetime" components.

However, "lifetime" doesn't mean they never need replacing. Chains can stretch, wear out, and eventually fail, even without reaching a specific mileage. The failure point is dependent on several factors:

* Driving style: Aggressive driving and frequent hard acceleration put more stress on the chain.

* Maintenance: Proper oil changes using the recommended viscosity are critical to chain lubrication.

* Engine conditions: Other engine issues can indirectly affect the chain's life.

Instead of a mileage-based replacement, focus on these:

* Listen for unusual noises: A rattling or slapping sound from the engine could indicate chain stretch or wear.

* Regular inspections: Have a mechanic inspect the timing chain during routine maintenance, especially if you notice any unusual noises. They can assess its condition and suggest replacement if needed.

* Oil analysis: Advanced oil analysis can sometimes detect metal particles from a wearing chain before it fails completely.

In short, there's no magic mileage number. Regular maintenance, attention to engine sounds, and professional inspection are far more important than relying on a mileage-based replacement schedule for a timing chain.