There are alignment ridges on the belts that keep the pulleys synchronized, the same way a timing chain or timing gear would work in other engines. Every ridge on the timing belts must hold to the pulley's to keep the camshafts and crankshaft synchronized.
However, on a worn timing belt the ridges start to round over and flatten. Once the integrity of the timing belt is worn enough to allow the camshaft to skip a link, the engine will be destroyed and no longer run.
Saturn engineers have determined the best time to replace the timing belt, and it's best to follow those recommendations. When the belt is functioning properly, the engine runs. Once the belt reaches that critical point of wear, the belt is no longer reliable and should be repaired.
Timing belts technically aren't "bad" until the camshaft starts to skip, at which point you buy an entire engine. When the camshaft skips a tooth on the belt, valves will impact with the piston and the engine will be completely destroyed.
Chain
The SC2 is an 'S' series Saturn, and all 4 cylinder engines of the S series Saturn's used a timing CHAIN rather than a timing belt.
The 4 cylinder Saturn engines used an "Oil bath" timing chain. The V6 Saturn engines used an "external" timing belt.
The V6 engine in a LS2 has a timing belt with replacement intervals at 100k miles
There is no timing belt. Saturn Ion's use a timing chain.
All of the Saturn 4 cylinder engines used a timing chain. The V6 Saturn's used a timing belt.
The V6 Saturn used a timing belt. The 4 cylinder's used a timing chain.
All Saturn 4 cylinder engines have an internal timing chain. All Saturn V6 engines have a timing belt.
All of the 4 cylinder Saturn vehicles used a timing chain. Only the V6 Saturn's used a timing belt.
All of the 4 cylinder Saturn's used a timing chain. All of the V6 Saturn's used a timing belt.
The Saturn sl2 does not have a timing belt, it has a timing chain. And under most conditions it does not need replacing.
The S series Saturn does not use a timing belt; all four cylinder Saturn's use a timing chain.