Replacing water pump - what about idler pulley?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ozymandias, May 6, 2012.

  1. ozymandias

    ozymandias Junior Member

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    The water pump on my 04 with 132k miles is rattling / wobbling (but surprisingly, not leaking). So I am going to replace the water pump, serpentine belt, and thermostat. The idler pulley seemed fine so I am wondering if I should replace it. What is the failure mode on the idler pulley and how will I know it is going bad without having to check it? Or should I just go ahead and replace it?
     
    #1 ozymandias, May 6, 2012
  2. Munpot42

    Munpot42 Senior Member

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    You are in there anyway so why not replace it to be on the safe side. For me, I'd hate to do that work and go back in there 6 months later to replace a pulley.
     
    #2 Munpot42, May 6, 2012
  3. ozymandias

    ozymandias Junior Member

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    Replacing the pulley would take less than 5 minutes.
     
    #3 ozymandias, May 6, 2012
  4. css28

    css28 Senior Member

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    The absolute failure mode would be bearing seizure which would result in it throwing or destroying the belt. The way that you'd know it is going bad would be noise (high pitched bearing squealing at first, harsher, more grindy noise later). Given the isolation of the engine compartment from the cabin, you'd probably notice it as reflected noise off of buildings or other vehicles. The noise can continue for a long time before the pulley seizes though. Listen under the hood every 6 months or so and you should be good.

    - Chris
     
    #4 css28, May 6, 2012
  5. ozymandias

    ozymandias Junior Member

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    Thanks...that's what I needed to know...I'll save the $45 for now and replace it when I hear it start to go bad. The car is parked in a garage so I should hear it pretty easily....that is how I found out the water pump was on it's way out.
     
    #5 ozymandias, May 6, 2012
  6. ozymandias

    ozymandias Junior Member

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    Hmm, I just realized that Rock Auto sells Bosch water pumps for half the cost of OEM...I assume they are just as good?
     
    #6 ozymandias, May 6, 2012
  7. css28

    css28 Senior Member

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    Bosch is as good a name as any, though I don't usually think of them for water pumps.
     
    #7 css28, May 6, 2012
  8. kohnen

    kohnen Grumpy, Cranky Senior Member

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    1 - Replacing the idler pulley is really REALLY easy on the Prius. About 5 minutes - you don't have to mess with the water pump or the belt.

    2 - The thing that fails on the pulley is the bearing. That bearing is a 6301 size bearing - really pretty stout for what it does. If you're handy, you can simply replace the bearing - for example: 6301-2RS Bearing 12x37x12 Sealed Ball Bearings

    3 - If you simply replace the bearing, it will cost you ~$10 for a high quality bearing.
     
    #8 kohnen, May 7, 2012
  9. ozymandias

    ozymandias Junior Member

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    Hmm, that's interesting. Thanks for the info! Unfortunately I don't have a press to replace the bearing. Anyway, it sounds like I might never have to replace the idler pulley anyway. So I'll cross that bridge when I get to it! :)

    After shipping costs and all the other parts (thermostat, gasket, belt), RockAuto wasn't a whole lot cheaper so I just went with the OEM water pump.
     
    #9 ozymandias, May 7, 2012
  10. Mike Mc

    Mike Mc '16 Prius 4, '13 Prius 3

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    OZ- I replaced the water pump in our '06 last year. Not a difficult job but it does require you to get into some tight spots. You should take off the pulley to gain easier access to the water pump anyway, so i say change it while you have it off. I would also recommend changing the thermostat while you're there for <$15 and the serpentine belt(if you haven't changed it yet). Oddly enough the pulley is the most expensive replacement part in this group. As for the Bosch water pump it is probably just as good as the original. I think you be amazed as I was about how small the water pump actually is. I took pictures of the process when I did the water pump replacement with the intention of putting a sticky on the site...but life has gotten in the way. I will make an effort to get it done in the next day or so.
     
    #10 Mike Mc, May 7, 2012
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