water pump tests once belt is off?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by pasadena_commut, Mar 14, 2026.

  1. pasadena_commut

    pasadena_commut Senior Member

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    If it isn't too hot (50:50 at this point, it was in the 90s today) I'm going to change the belt for the water pump this weekend. The pump is coming up on 60k miles according to Toyota's service records. (It was changed before we bought it.) Last time I looked it wasn't leaking at all and I have no reason to think it has an issue. Still, since the belt will be off, might as well take advantage of that to test it to the extent possible.

    Is there anything that I might deduce about the pump from futzing with the pump pulley once the belt is off? If a pump is sitting on a bench dry and its bearing is bad it will stop quickly when spun, but that test isn't going to work with the blades immersed in liquid. Maybe just turn it slowly and feel for grinding, places where it takes more force, clicks or the like? How much in/out play should there be? The pulley could be given a light pull out or push in, to see if it moves too much or not enough.

    Thanks.
     
    #1 pasadena_commut, Mar 14, 2026
  2. BiomedO1

    BiomedO1 Senior Member

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    Everything your describing here is by feel; so if you don't do this kind of work on a regular basis or have enough experience doing this type of work - How would you know?
    There shouldn't be any vertical or horizontal movement and the pulley should spin free - no rough spots. The dry spin test on the bench is invalid and highly subjective. I don't expect an old fashion 60K mile water pump to have issues, unless the belt has been over-tightened. If there's a bearing issue, the weep hole would be dripping. A bad bearing would cause the pulley to wobble a bit and cause the seal to leak. That's an objective test.

    Hope this helps......
     
    #2 BiomedO1, Mar 14, 2026
    Last edited: Mar 14, 2026
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