Of course not, but perhaps the other way around.
If the water pump is driven by the timing belt and you are changing the timing belt, yes you change the water pump at the same time. It's alabor saving thing. It takes a lot of time to get to the timing belt and the water pump is right there.
If the water pump is driven by the serpentine belt, no, you don't change the water pump until you have problem with the water pump as it isn't that difficult to get to it.
On my Honda, timing belt and water pump both get changed.
For $26 extra for the water pump, it is a no-brainer to change it when you do the timing belt.
It depends upon the car, and upon which belts you mean. If you are talking about fan belts and accessory belts or the single serpentine belt that replaces multiple fan belt/accessory belt combinations, then no. These are easily accessible and do not require significant labor to change.
On the other hand, if you are talking about the timing belt on a car whose timing belt also drives the water pump, the answer is most likely yes.
Changing the timing belt generally requires several hours of labor, and in the process of changing it, the mechanic is afforded access to the water pump. Although the water pump may be operating fine at the service interval for changing the timing belt, it may well fail within 10-20K miles, causing you to pay for the same labor to remove the new belt to access it. Accordingly, while it may seem unnecessary at the time, it is generally cost-effective to do both at once.
It depends on the engine. If the water pump is timing belt driven it is often changed with the water pump, but when I did the timing belt on my daughter's 2002 Sienna last month I left the water pump alone - it took special tools. In the 2007 and later Sienna with the 3.5L V6 the water pump is driven by the serpentine belt but the engine/transaxle has to be removed from the vehicle to replace the water pump.
only if you can afford that preventive maintenance would i do that and only if the manufacturer recommends it.
