The manual for my 1999 Volvo S70 sedan says that the timer belt should be replaced at 100,000 miles. My car has but 60,000 miles but the dealership tells me that the belt should be replaced now as the car is 10 years old.
I wonder which is the operative function: age or use?
Whichever comes first…If the belt breaks, your car is salvage. An independent shop will replace the belt for somewhat less than a dealership…
Both. 10 years is too long for that belt. It should be replaced. Doesn’t your manual also have a time interval? Most do. My Toyota manual specifies 60,000 miles or 7 years. Typically it is whatever comes first.
Age is as much a killer as use. The rubber breaks down through use and age. Once the rubber has broken down below a certain tensile strength, failure will happen.
…VDC heaves a heavy sigh…
As the maintenance schedule in your glove compartment will verify, virtually all maintenance requirements have both an odometer mileage value and an elapsed time value, with the proviso, "whichever comes first.
Thus, your low mileage car is due for a timing belt replacement. Truthfully, I suspect that it is overdue for this service, and that the replacement of the belt was called for at ~8 years of elapsed time. You could double-check my estimate by simply referring to the Volvo Maintenance Schedule that should be sitting in your glove compartment.
Failure to replace the timing belt promptly will expose you to an incredibly high repair bill when the belt snaps. Please note that you will have no warning before the belt snaps. And, since this failure is unlikely to take place in your driveway, please consider what a totally “dead” engine, loss of power steering, and loss of power brake boost would be like when driving at highway speeds.
You could probably replace the timing belt, water pump, serpentine belt, and all belt tensioners now for ~$500-$700. Or, you could wait until the belt snaps and pay somewhere north of $3,000 for the above-noted procedures + repairs to piston and valves that were damaged by the belt failure. (Since it is a Volvo, my maintenance/repair figures could be unrealistically low.)