One is a scheduled replacement you must not skip; the other lasts far longer. Getting it wrong can cost you an engine.
Buried inside your engine is one of two things keeping everything in sync: a timing belt or a timing chain. Which one you have changes your maintenance completely, and getting it wrong can mean a totaled engine.
A timing belt is made of reinforced rubber and must be replaced on a schedule, commonly every 60,000 to 100,000 miles depending on the vehicle. A timing chain is metal, runs in oil, and is designed to last far longer, often the life of the engine, though it's not entirely maintenance-free.
Most modern engines are "interference" designs, meaning the valves and pistons share the same space at different moments. If the timing belt snaps, that timing is lost, pistons slam into open valves, bending them and sometimes damaging more. The result is a repair that can cost several times what a scheduled belt replacement would have. That's why the interval is not a suggestion.
On many engines the water pump is driven by the timing belt and sits right behind it. Since the labor to get in there is the expensive part, replacing the water pump, tensioner, and idlers at the same time as the belt is the smart, economical move.
Tell us your year, make and model and we'll tell you exactly, and we won't sell you a belt job on a chain-driven engine. If you're near the interval or bought the car used with no records, get it checked. See our timing belt & ignition service, or call (703) 243-3080.
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