Water Pump question for all subaru owners

[0976]

My subaru has a water pump that does not have teeth on the pulley, it's just smooth, and is turned with the back of the timing belt.

I think that having teeth is a requirement, because what happens when that belt gets old and the rubber starts to harden, will it still turn that water pump just as good as if it had teeth. I would think it would slip.

What do you think? Is both ways just as good?

[RahX]

I'm pretty sure something like that is engineered properly as it is rather rare to have a bad water pump or one that doesn't pump enough on a Subaru. It is not a positive displacement pump so it is more like a fan which doesn't have nearly as much resistance.