Timing Belt

At what mileage is a timing belt replaced? My car is a Pontiac Grand Prix 2002 with 138,000 miles.

Are you sure that your car has a timing belt?
I seem to recall that GM engines, such as the ones in their mid-size & large cars, utilize timing chains. (Timing chains are essentially lifetime components, but if yours begins to approach the need for replacement, you will hear it making a metallic vibrating noise.)

However, rather than relying on my recollection, you can consult the ultimate source, namely GM.
Simply open your Owner’s Manual and find the section that shows the mfr’s maintenance schedule. If your car has a timing belt, that procedure will be listed for an interval such as every 105k miles or 8 years, whichever comes first, or…every 90k miles or 7 years, whichever comes first.

If there is no listing for timing belt replacement in the mfr’s maintenance schedule, that is your confirmation that this engine utilizes a timing chain, rather than a timing belt.

In the event that you don’t have an Owner’s Manual, this is just one example of why you need one. E-bay is a good source for low-cost copies of your Owner’s Manual.

Grand prix motor is 3.1 or 3.8 pushrod motor. No timing belt. There is a timing chain which is not serviced. Unless it breaks.

Where did you get the idea that you need to replace the timing belt?

Learning by osmosis. Any car over 100k miles needs a timing belt. Hmm, maybe my car has timing belt? It’s good that any car owner takes a little interest in maintenance. So now u learn that ur motor does not have belt.

@cavell, this newbie OP can probably do well without the sarcasm.
Also, “u” and “ur” are not words, they only serve to make my eyes hurt.

+1 for @circuitsmith.

Last year Pontiac Grand Prix that had a timing belt was the Quad 4 engine in 1996.