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Radiator Coolant Overflow Expansion Tank Cap Replacement

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Umar Farooq, Apr 25, 2021.

  1. Umar Farooq

    Umar Farooq Junior Member

    Joined:
    Aug 8, 2012
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    Vehicle:
    2008 Prius
    Model:
    One
    Hello,

    I hope everyone is doing well and staying healthy. I had a quick question regarding the replacement of the radiator overflow expansion tank cap. I popped the hood a few days back and notices that the cap on there was broken. So I went a head and ordered a new one. I tried replacing it, but the cap does not form a tight seal with the tank. I assumed the part was wrong, so I ordered another one from my Toyota dealership. However, I ran into the same issue. Is there a sealant or some specific method of putting the cap on?

    I have attached a picture of the tank.

    Any help would be appreciated!

    Thanks.
     

    Attached Files:

    #1 Umar Farooq, Apr 25, 2021
  2. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
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    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    In an overflow-bottle system like Gen 2, it isn't necessary for the cap on the overflow bottle to seal airtight. Coolant routinely moves between the pressurized radiator and the bottle in normal operation, and the bottle remains at atmospheric pressure, with air entering and exiting at the cap.

    It is different with a degas-bottle system like Gen 3 has.
     
    #2 ChapmanF, Apr 25, 2021
    Fred_H likes this.
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