No "how-to" head gasket posts for a Gen4?

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by C Clay, Jul 26, 2026.

Tags:
Page 2 of 2
  1. BiomedO1

    BiomedO1 Senior Member

    Joined:
    Mar 27, 2021
    4,584
    2,408
    0
    Location:
    Left Coast
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    That's not a definitive test; since that could simply be condensation in the exhaust system from last night. That's more like an "old wives tale test" to tell yourself your correct.

    Do whatever you want; since it's your time and money. You've been given the proper procedures to verify a head gasket problem.o_O:(:sleep:
     
    #21 BiomedO1, Aug 3, 2026 at 2:50 PM
  2. C Clay

    C Clay Member

    Joined:
    Nov 24, 2012
    403
    80
    0
    Location:
    Lexington, KY
    Vehicle:
    2019 Prius
    Model:
    L Eco
    You ask a good question- does it death rattle? Nothing death rattles like the gen 3- so no. Misfires reported only scanner app- yes.

    As far as the coolant hoses that I bypassed- I have a picture up there. How else does the coolant enter the exhaust? I’m asking because I don’t know.
     
    #22 C Clay, Aug 3, 2026 at 6:16 PM
  3. C Clay

    C Clay Member

    Joined:
    Nov 24, 2012
    403
    80
    0
    Location:
    Lexington, KY
    Vehicle:
    2019 Prius
    Model:
    L Eco
    I appreciate everyone’s perspective and help- It’s not that I’m not doing those tests to rule out that it’s a head gasket -rather I keep trying to figure out how to do the head gasket if that’s my next step.

    If the head exchanger has already been bypassed- what else could it be?
     
    #23 C Clay, Aug 3, 2026 at 6:20 PM
  4. Bill Norton

    Bill Norton Senior Member

    Joined:
    Dec 15, 2012
    2,240
    750
    0
    Location:
    MONW, Ks.
    Vehicle:
    2019 Prius
    Model:
    L Eco
    Isn't there a EGR cooler in a Gen4?
    That EHR is for quick warm ups of the coolant, no? And not related to the EGR system, no?

    Yeah, so start testing.
    What happens if you leave 15 psi on the coolant system overnight? Does it lose pressure? Does it lose coolant?
     
    #24 Bill Norton, Aug 3, 2026 at 9:30 PM
  5. Bill Norton

    Bill Norton Senior Member

    Joined:
    Dec 15, 2012
    2,240
    750
    0
    Location:
    MONW, Ks.
    Vehicle:
    2019 Prius
    Model:
    L Eco
    So you are saying it starts and sounds fine?
    You get a code for what kind of misfire? But don't notice any problems,, other than that steam cloud coming out the back?
     
    #25 Bill Norton, Aug 3, 2026 at 9:35 PM
(You must log in or sign up to post here.)
Page 2 of 2