When you replace your timing belt, your mechanic might recommend replacing your water pump and other components along with it.
The reason many mechanics recommend replacing these parts at the same time is that a lot of them tend to have similar life spans. In other words, if your belt is failing at 80,000 miles, your water pump might be on its way out, too.
Sure, you could always replace your timing belt and water pump separately, but if you do them at the same time, you could save around $400 in labor costs. Your mechanic has to dig pretty deep to replace your timing belt or your water pump, “and we might as well replace both while we’re in there,” said Sean Kim, an experienced Atlanta-area mechanic.
That being said, any time a shop insists that you have to replace multiple parts at once, it’s best to get a second opinion before paying. Per Kim, “I’d always check for validity unless it's a reputable shop that you're familiar with.”