[ganda1f]

I replaced the water pump on a friend's '94 Corolla at 144k miles due to a slight leak. But on my '95 Corolla it is still good at 171k miles. No leaks, no noise. But I will certainly replace it at next timing belt at 180k miles.
What is more likely to fail is the o-ring between the pump and the engine block. At 144k miles it was hard as rock and I had to carefully dig it out with a screwdriver, watching not to scratch the surface.

On the 4AFE the water pump is not that critical, even if it seizes, because it is not driven by the timing belt. On engines with timing-belt driven water pump, the pump is usually changed at every timing belt change in order not to risk breaking the timing-belt if the pump happens to seize. It is the same principle as with timing-belt tensioner which is also changed with the belt.

 

[1jzdreamer]

For the timing belt, no seals need to be replaced. anything you replace you do so by choice and risk not seating the new gasket right or creating a leak. I never changed any seals on my 4afe until they leaked.
The stock water pump for me have been good for 90-120 miles if not run dry, with regular coolant changes.

Id just do the belt, but remember, if the belt breaks, nothing happens on the 4af motor. Itll just stop running. Its a non interference motor. I changed my first timing belt at 105 miles and it still looked fine and would have gone another 25.

 

[speedy25]

Anything rubber with hot oil behind it will be hard as a rock by 100K miles. Although most just want to ignore seals until they leak, the OP's idea to be pro active for keeping the oil INSIDE the engine is a good thing. I also did a car recently that did not ever have the cam seals replaced and at 200k the seals had made a nasty score line on the sealing surface. Change the crank and cam seals for easy insurance. Its NOT a hard job. and certainly easier than replacing it later, along with your timing belt if it does leak.

-SP

 

[1jzdreamer]

I guess its dependant on if you have done regular service on the car. My seals were still soft with no marring, and were the originals. I just have seen too many cases where someone without the proper seal tools buggered the seal during install or installed it improperly and only created headaches.

To each there own.