Q&A

Yes putting in a new belt will change the tension on all attached parts. The question is how old is the present water pump, and in what codition is it?

On many front front wheel drive cars there is a lot of labor involved to remove other engine parts and brakets to get into the place where the timing belt goes, and putting them back into place after the new timing belt is placed into position. Thus the price for having a new timing belt installed is mostly LABOR.

WATER PUMP. All the same labor for the timing belt has to be repeated to get to the place where a water pump is to be installed. It takes just a little more LABOR to replace the water pump at the same time it is apart for the timing belt.

YES AND NO.
Yes it is usually a good practice to replace a water pump when the timing belt is replaced.

No it probably does not put more tension on the water pump. There is a spring loaded belt tensioning device separate to maintain the belt tension whether a new or old belt.
that maintains the same tension

My experience. This turneed out to be dangerous. I bought the car with 76,000 miles on it. I did not know whether or not the timing belt had been replaced. The car appeared to have been well maintained.

The book said replace the belt at 90,000 miles if not done at 60,000 miles. I was expecting to replace the water pump when the belt was replaced.

I checked the belt condition periodically. It kept on looking good and the water pump had not leaked.

My daughter was driving on a freeway in a busy city with heavy speeding traffic and no extra side of road to park. Engine quit, she was able to steer into a tight space just past a turn off.

Car now had 150,000 miles on it, water pump shaft froze up, meaning it would not turn. This belt friction immediatly burned through the timing belt and broke it.

This could easily have been a serious accident totaling the car and injuring or killing my daughter.

Some engines have very serious damage to valves and other parts if the timing belt breaks, This engine was OK
She got it towed and we had a new water pump and timing belt installed.

Another possible reason to replace your water pump now, even though it is not worn out yet. It could fail with a gradual leak trhat is undetected at first, then when enough coolent has leaked the engine would overheat. Some drivers would not know how serious this can be and keep driving with a result of ruining the engine.

Therefore it is wise to heed the advice and get the new water pump at the same time as the new timing belt.

how can i install a timing belt