1. Attachments are working again! Check out this thread for more details and to report any other bugs.

3rd gen Under dash leak

Discussion in 'Gen 3 Prius Main Forum' started by donzoh1, Apr 11, 2019.

  1. donzoh1

    donzoh1 Active Member

    Joined:
    Jan 19, 2019
    434
    149
    0
    Location:
    Lenexa, KS
    Vehicle:
    2004 Prius
    Model:
    Five
    I recently replaced the head gasket on a 3rd gen Prius. Water has leaked below the dash inside the car. I'm guessing this means I should have put RTV sealant on the trim piece that connects to the base of the windshield.
     
  2. Raytheeagle

    Raytheeagle Senior Member

    Joined:
    Jul 1, 2016
    11,251
    15,474
    0
    Location:
    Bay Area, California
    Vehicle:
    2019 Prius Prime
    Model:
    Prime Plus
    You sure it’s not the AC system drain?

    I’ve removed the windshield wiper cowling many times and never had a leak internally.

    Might just be a coincidence.
     
    Mendel Leisk likes this.
  3. BZzap!

    BZzap! Senior Member

    Joined:
    Jun 13, 2012
    1,607
    877
    0
    Vehicle:
    2012 Prius
    Model:
    Two
    During the disassembly did you happen to have difficulty removing the heater hoses? What you may have done is compromised the heater core. Another possibility/coincidence is the evaporator housing drain might be plugged allowing for water build up and subsequent leaking.
     
    Raytheeagle likes this.
  4. donzoh1

    donzoh1 Active Member

    Joined:
    Jan 19, 2019
    434
    149
    0
    Location:
    Lenexa, KS
    Vehicle:
    2004 Prius
    Model:
    Five
    I don't think I damaged the heater hoses or heater core but if this turns out to be coolant, I will check more in that neighborhood. I have a vague memory of a drain line that I thought was a coolant reservoir overflow tube so maybe that relates to a.c. condensation. Where is the condensation line located?
     
  5. BZzap!

    BZzap! Senior Member

    Joined:
    Jun 13, 2012
    1,607
    877
    0
    Vehicle:
    2012 Prius
    Model:
    Two
    The evaporator drain is under the glove box in the extreme L/corner by the console and exits out to the undercarriage. You’ll have to pull back the carpet to get unrestricted access. If the carpet is saturated in this area there is a very high probability this is your problem.