Exhaust Manifold Gasket (on head) leaking?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Robert John, Nov 25, 2021.

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  1. Robert John

    Robert John Junior Member

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    2008 Prius
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    Two
    Smelling exhaust when '08 Prius (140,000 km) is at a stop & on 'Fresh Air' (no problem when on 'Recirculate'). No DTCs. Drove front up on ramps & wiggled underneath - don't see/feel obvious signs of leaks on the cat.con. donught (brand new SS muffler). Sooo... I'm guessing it's the exhaust manifold gasket. It's REAL tight up in there and the 3 bolts & 2 nuts look seriously rusted. Muffler shops here are thieves, and if I take it to dealer, it'll be cheaper to just buy another 2nd hand '08 ;-) Instructions in Prius shop manual don't address in-situ replacement, (and from what I read in this forum I do not want to try to remove the exhaust header to replace the gasket ;-)
    Q1: How common is a leaking head exhaust manifold gasket on an '08 Prius w 130,000 kms?
    Q2: Any tips/tricks on how to confirm if it's the head exhaust gasket or cat.con. flange gasket that's leaking? It's hard to get my hand or eyes up in there close enough to confirm.
    Q3: Not sure where this question belongs: Sometimes when the engine decides to shut itself off, it's a bit rough (like a second of 'run-on'). The original plugs were all fine but I replaced them with new top-of-the-line platinum anyway. No change. Any ideas?
    Thanks! This forum rocks!
     
    #1 Robert John, Nov 25, 2021
  2. ChapmanF

    ChapmanF Senior Member

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    I haven't seen everything, of course, but I'm pretty sure I have never ever heard of a leak originating at an exhaust-manifold-to-head gasket without being somehow provoked.
     
    #2 ChapmanF, Nov 25, 2021
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  3. dolj

    dolj Senior Member

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    Most of the time it is the donut gasket and don't assume that because it is new that it is not the problem, especially if it a 3rd-party gasket.
     
    #3 dolj, Nov 25, 2021
  4. mr_guy_mann

    mr_guy_mann Senior Member

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    I have only seen leaking "doughnut" gaskets at the flex connection on Toyotas. I have yet to see a leaking exhaust manifold gasket on a Toyota 4 cylinder. I only use Toyota doughnut gasket because most every aftermarket one doesn't fit correct and will often leak- sometimes only when the engine is under load

    Posted via the PriusChat mobile app.
     
    #4 mr_guy_mann, Nov 27, 2021
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