engine water pump failed to seal?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Chris77*, Mar 17, 2026 at 11:11 PM.

  1. Chris77*

    Chris77* Junior Member

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    I attempted diy engine pump. I followed instructions of sr member Tombukt2. He set me up with a repair that seemed straightforward and i found a place to work on it at a friend. Tombukt2 advised take the pump off without draining any fluid this was the correct method if fluid is still good as you loose the min about a quart as promised.

    I bought a aisin pump it was marked to me as 20$ cheaper and still oem. It came with a new metal gasket. I torqued bolts to (8lb-ft, 96 in-lb). The repair was tight and messy but otherwise I got it done. When I went to burp it i hear the coolant hit the pavement as the pump didn't seal. Hopefully someone knows how to remedy this?

    Also, I am concerned that the coolant needs changed. What came out of there was orange and murky. The previous owner told me dont worry about engine coolant as he had changed the thermostat the same yr i bought the car and had changed fluid.

    Any help remedy these problems is appreciated.
     
    #1 Chris77*, Mar 17, 2026 at 11:11 PM
    Last edited: Mar 18, 2026 at 12:56 AM
  2. Chris77*

    Chris77* Junior Member

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    I am going to add an update. From my personal research AI thinks this is a gasket issue and somewhat common on prius. It said that this is a case where one doesn't want to go oem because after market is more forgiving on old cars. AI recommended FEL-PRO. i will say i was having problems seeing what i was doing so i did bend the gasket a little when i was setting it up. Its a pain the metal gasket is this sensitive, if the culprit. How would you guess go about it if you agree this is a gasket issue?
     
    #2 Chris77*, Mar 18, 2026 at 1:02 AM
  3. Chris77*

    Chris77* Junior Member

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    also i am going to do a proper inspection on the fluid as i feel like this might be the most important part.
     
    #3 Chris77*, Mar 18, 2026 at 3:16 AM
  4. xw20_driver

    xw20_driver Member

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    This is good to know. My 2007 has a weepy and crusty WP and I also have a new AISIN pump from Rockauto that I hope to tackle in the upcoming weeks. I plan to replace the thermostat as well and will likely drain out as much of the coolant from the system as possible including the storage tank.

    Can you describe the coolant being murky? When I look into the radiator neck, my red coolant appears cloudy and opague and not transparent.
     
    #4 xw20_driver, Mar 18, 2026 at 10:02 AM
  5. Tombukt2

    Tombukt2 Senior Member

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    If you're fluid looks like crap I would drain it at the lowest point and add new free mixed Asian red fluid for the leak usually what I have to do w meccie pumps is spray gasket adhesive on the pump put the gasket on the pump let that set. Use my elec for crinder to cleanup timing cover mating surface. Then assemble . I haven't had one of these mechanical pumps leaking 40 years putting it on or afterwards . not sure on leak . Hold you're camera under the pump as it's leaking .
     
    #5 Tombukt2, Mar 18, 2026 at 1:42 PM
  6. pasadena_commut

    pasadena_commut Senior Member

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    Leaking gaskets are often from improper preparation of the surface. Either it wasn't cleaned well, or it was scratched when it was cleaned. Contamination of the surface on the new part with an oily/greasy,dirty finger can also cause this. Some gaskets can be installed incorrectly (rotated or flipped over) and will then leak. Were all the bolts properly torqued ? If so, when was the last time the torque wrench was calibrated? They can become quite inaccurate. It could be a bad gasket but Aisin is usually a quality product. What type of gasket do they supply?

    Regarding murky coolant, ours was pretty much clear at more than 6 years old. (Not sure how much more.) It was the same color as the replacement coolant. Get some pH paper. If the pH has dropped significantly that is a good sign the coolant is worn out, and once it becomes neutral, or much worse, acidic, it can start dissolving metals. (Slowly.)
     
    #6 pasadena_commut, Mar 18, 2026 at 1:51 PM
  7. Chris77*

    Chris77* Junior Member

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    I just did fluid inspection. I think its okay. It looked weird and dirty in the black pan. I put a white tissue in it and its defiantly pink. i think the turbidity came from inside the engine bay. Its messy when pull that pump off the side.

    I been calling mobile mechanics. Its hard to find an honest rate. What the part i used is a Aisin part that walmart sells. I think what we are going to do is return that part to walmart as failed and just start over. One guy put it its OEM like not OEM.

    Are you finding you need to put a sealant on the pump? I see some guys doing that in diy vids but its not technically the instructions.
     
    #7 Chris77*, Mar 18, 2026 at 1:53 PM
  8. rjparker

    rjparker Tu Humilde Sirviente

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    First, aftermarket for Toyota water pumps is a bad idea. Not necessarily for leaks (rare in any case) but for long term reliability.

    Counterfeits exist with fake Toyota packaging. The Car Care Nut has a video on how to detect fakes.

    Toyota gaskets are not a problem and are generally the safest buy. Some like Fel Pro for Gen3 head gasket but that is a choice advocated on forums looking for a solution to a design issue. In fact Toyota upgraded that particular gasket as well.

    Solution for your gen2 water pump? Do it again with a new gasket. Drain your coolant first. Carefully clean and inspect the mating surfaces. Make sure all the bolts are in and torqued to spec.
     
    #8 rjparker, Mar 18, 2026 at 2:06 PM
  9. Chris77*

    Chris77* Junior Member

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    Looks like we going to put a duralast in it from down the street mobile mechanic says he wouldn't mess with oem on a mechie. Frustrating but i guess should be resolved soon. not sure on walmart aisin parts as i am going to return it.
     
    #9 Chris77*, Mar 18, 2026 at 2:58 PM
  10. Tombukt2

    Tombukt2 Senior Member

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    Be interesting to lay the dura's last side by side with the whatever it is cannot imagine they'll be much to see
     
    #10 Tombukt2, Mar 18, 2026 at 3:21 PM
  11. Tombukt2

    Tombukt2 Senior Member

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    But where is the leak on the gasket mating surfaces coming out of the weep hole of the brand new pump? That's kind of more interest than brands
     
    #11 Tombukt2, Mar 18, 2026 at 3:29 PM
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