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Need anti-seize on existing spark plug?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by zm15, Jul 4, 2022.

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  1. zm15

    zm15 Junior Member

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    I pulled the plugs to check on them, they only have 30k miles on them - just wanted to check as i was doing other maintenance.
    Do I need to apply the anti-seize grease for these existing ones?

    Also.... cylinder #4 had a misfire so I check the plug and the body of the plug had oil on it.... what could that mean? Ok to put the plug back in after wiping it off?

    I'm in the middle of a EGR Valve and Cooler replacement, intake manifold cleaning and PCV with oil catch can install. So perhaps that might solve it?
     
    #1 zm15, Jul 4, 2022
  2. JC91006

    JC91006 Senior Member

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    How many miles are on your car? I think you should clean off the plug and switch the plug with another cylinder. See if that changes things. If you still get the misfire on #4, then swap the coil pack as well. If after swapping the plug and coil pack to another cylinder and you still get a misfire on #4, then you would have to look elsewhere.

    If the misfire jumps to the swapped cylinder, then you just have a bad plug or coil. You may want to change out the valve cover gasket if there is evidence of oil seeping out of it (can explain oil getting into 4)

    You don't need to use anti-seize on NGK or Denso plugs
     
    #2 JC91006, Jul 4, 2022
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  3. Mendel Leisk

    Mendel Leisk Senior Member

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    Torque spec, presumably for clean/dry threads, is 15 foot pounds. If you do use anti-seize, I'd put it on sparingly, wipe the threads with a cloth (leaving just a slight residue in the threads), and reduce torque to 12~13 foot pounds. A 1/4" (or 3/8" in a pinch) drive torque wrench is best for low torque values like this.
     

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    #3 Mendel Leisk, Jul 4, 2022
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  4. zm15

    zm15 Junior Member

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    Thanks @JC91006 , it has 165,000 on it. Good idea to swap the spark plugs. I looks like there might be a little oil in #2 cylinder as well.

    Another item of note... I only got the misfire on #4 after the engine would hesitate when turning on/off the ICE when accelerating. It's a known thing that it could be the EGR and intake manifold, thus the replacement of it (didn't have time to clean the parts).

    But the interesting thing is, I disconnected the EGR valve connector to see if it was that system, and sure enough - no misfire or hesitation when it was disconnected.
     
    #4 zm15, Jul 4, 2022
  5. JC91006

    JC91006 Senior Member

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    I don't know if you are already on your way to a head gasket failure. Are you loosing coolant?

    You may want to hold off on the EGR valve/cooler replacement. You might just want to do a good cleaning and see if your problem improves. If you continue having a misfire, you could have the dreaded head gasket leak.
     
    #5 JC91006, Jul 4, 2022
  6. ASRDogman

    ASRDogman Senior Member

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    If you have oil on the plug, they valve cover gasket is leaking.

    You should only change the spark plug with another cylinder, like #3.
    If you still get the missfire code on #4, you know it's NOT the plug.
    Then switch the coil pack to #3. If the missfire moves to #3, you know it's the pack.

    If it stays on #4, then it's neither, and possibly the wiring. Or a head gasket leaking, which is less likely.

    If the missfire code does not come back, they the oil leaking is your likely problem.
    Either way, the valve cover gasket needs to be changed.

     
    #6 ASRDogman, Jul 4, 2022
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  7. zm15

    zm15 Junior Member

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    I don't seem to have any coolant leaking, it's stayed at the same level for years.

    I already replaced the EGR system, and I'm glad I did, it was quite bad. The intake manifold was as well.
     
    #7 zm15, Jul 4, 2022
  8. JC91006

    JC91006 Senior Member

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    Well you may just need a valve cover gasket, hopefully it's just the oil on the plugs giving it the misfire.
     
    #8 JC91006, Jul 4, 2022
  9. zm15

    zm15 Junior Member

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    Another item of note... I only got the misfire on #4 after the engine would hesitate when turning on/off the ICE when accelerating. It's a known thing that it could be the EGR and intake manifold, thus the replacement of it (didn't have time to clean the parts).

    But the interesting thing is, I disconnected the EGR valve connector to see if it was that system, and sure enough - no misfire or hesitation when it was disconnected.
     
    #9 zm15, Jul 4, 2022
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