Is there any way to determine whether a water pump needs to be replaced before it fails completely? I realize that if it dies, then I'm not going to get far. Am I better off waiting until it does than trying to replace it before that happens? I know it's going to be a fairly expensive repair.
I have a Corolla with 125,000 miles. Could the water pump last another 125,000 miles? I realize that it could die tomorrow, but how likely is that?
It sounds like you're asking several questions at the same time.
In terms of the symptoms of failure, you don't give a lot of information about your specific car. However, some basics always apply: leaks (especially at the bottom of the timing belt cover) and basic failure to move the coolant (are you overheating this summer?).
In terms of cost, you're looking at a fairly labor-intensive replacement. Have you already replaced the timing belt? That is in the same vicinity as the water pump and, if the mechanic is already replacing the timing belt, that's a good time to take care of the water pump itself.
Finally, in terms of consequences, this part is in the category of things that can bring your trip to a halt. No water pump = no coolant = no driving.
Of course, water pumps generally don't fail catastrophically, exploding in a cloud of coolant vapor. That said, it's going to go eventually. If you're lucky it will last for a while. Time to start setting a little cash aside for the eventual replacement?
Impossible to say. I can only offer my own anecdotal Toyota experience. I had to have the engine rebuilt on my MR2 at 180,000 miles (due to oil pump failure). The original water pump was still working fine, no leaks, no problems at all at that point. However, since the whole engine was out and being rebuilt, we replaced it. At my 240,000 mile timing belt change, my mechanic (very experienced, and a friend as well) went ahead and replaced the water pump again as a preventative measure as he says that it's rare for Toyota water pumps to make it past 90,000 miles... YMMV I guess. :-)
I drive a 2006 Camry, and just crossed 95K miles. Although the pump did not fail, it did start foaming around the gasket so I had that taken care of before it got bad. I foresee seals, and gasket failing before the pump does.
