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Prius c spark change plug

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by ufourya, Jul 12, 2014.

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  1. ufourya

    ufourya We the People

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    I passed the 58,000 mile mark and thought I'd take a look at my spark plugs. They did not look bad at all but in checking the DENSO spark plug site:
    Frequently Asked Questions: DENSO Iridium
    I discovered they recommend replacement after 30,000.
    Only iridium plugs available locally were Champion 9002. I got some and began the change. After removing the first plug, I noticed a difference between the OEM DENSO 3485 (also listed as FK16R-A8) and the Champion. I liked the precision look of the DENSO compared to the CHAMPION:

    gap close-up.jpg 2.jpg
    So ordered some from Rock Auto and returned the Champs.

    To make the replacements first undo the 10 mm bolts holding down the coil sleeves:

    IMG_3674 (2).JPG

    Then using a 5/8 inch spark plug socket, remove the plug. You will need an extension to reach:

    IMG_3684 (2).JPG

    Unscrew. I vacuumed the opening beforehand just to make sure nothing had dropped into it. Then place the new plug into the socket and hand tighten. DENSO has torque recommendations:

    APC - 2014.07.12 15.07 - 001.3d.jpg

    If you use an anti-seize lubricant on the threads (and I did) you are to cut the torque in half. So I tightened to 11 lb-ft. with a torque wrench.

    I forgot to mention a couple of things. The plugs are 14 mm flat seat. And one has to unplug the clip from one of the coil sleeves in order to pull it up. you will have to turn it a bit to get it past the tubing.

    IMG_3679 (2).JPG
     
    #1 ufourya, Jul 12, 2014
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  2. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Wait a sec, no tearing the car half apart, windshield cowl, wipers and motors? That's progress Toyota!
     
    #2 Mendel Leisk, Jul 12, 2014
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  3. Mr Incredible

    Mr Incredible Chance favors the prepared mind.

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    Was the inside of the plug hole clean and dry?
     
    #3 Mr Incredible, Jul 13, 2014
  4. ufourya

    ufourya We the People

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    Yup.

    IMG_3678 (2).JPG
     
    #4 ufourya, Jul 13, 2014
  5. Mr Incredible

    Mr Incredible Chance favors the prepared mind.

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    *sniff*
     
    #5 Mr Incredible, Jul 13, 2014
  6. ufourya

    ufourya We the People

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    Are you crying or smelling?
     
    #6 ufourya, Jul 13, 2014
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  7. Mr Incredible

    Mr Incredible Chance favors the prepared mind.

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    Just a bit of dust in the eye...

    I don't think I've ever seen a Japanese plug hole without grit and oil. Sometimes LOTS of oil. Granted, my experience with non-American cars is limited, but I would be overwhelmed to find a hole clean, dry, and shiny. I'd have to just look at it for ten minutes or so before I even grab a wrench.
     
    #7 Mr Incredible, Jul 14, 2014
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  8. ufourya

    ufourya We the People

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    Ha ha. I was amazed that the old plugs look as good as they do. I wonder what I'm doing wrong.

    IMG_3706.JPG
     
    #8 ufourya, Jul 14, 2014
  9. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    The cables have a cap that overhangs the spark plug well, protects pretty well, coupled with the ornamental plastic valve cover. That said, there doesn't look to be much of a lip on the Prius c spark plug well.

    I've had a motorcycle with deeply recessed wells that had no protection, were full of crap, and some leaking coolant. They were pretty much FUNNELS for junk...

    I took an old plug, hacksawed off just the thread portion of the plug, and expoxy glued and length of slim wooden dowel to the thread.

    I could gently remove the plug, screw in this contraption, and then shoot compressed air in there, without the usual sparkplug in the way, blocking the air jet.
     
    #9 Mendel Leisk, Jul 14, 2014
    Last edited: Jul 14, 2014
  10. SageBrush

    SageBrush Senior Member

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    They look *great*
    For me the main problem with these long life plugs is forgetting about them entirely.
     
    #10 SageBrush, Jul 14, 2014
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  11. ztanos

    ztanos All-around Geek!

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    I could see this happening. Aren't they 120k mile change interval?
     
    #11 ztanos, Jul 14, 2014
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  12. col127

    col127 Member

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    What's the recommended time frame to change spark plugs? My car is at 42k miles... I've just been following the standard Toyota guidelines...
     
    #12 col127, Jul 14, 2014
  13. SageBrush

    SageBrush Senior Member

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    If memory serves, either 100k or 120k. Forum gurus have advised taking them out much sooner for an inspection and to apply a dab of anti-seize. There is a concern that at 100k+ miles even if they are working fine they will be hard to remove.

    I accept this reasoning, but honestly if I am going to take the trouble to gain access to remove the things, I'll just replace them.
     
    #13 SageBrush, Jul 14, 2014
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  14. ufourya

    ufourya We the People

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    The sleeve with the rubber gasket (large arrow) apparently does an excellent job protecting the well. I have not pressure washed or even hosed down the engine compartment. So I don't know how the well IMG_3677 (2).JPG could get too dirty or wet. Since we drive hybrids, the mileage on the ODO will not represent the mileage on the plugs. Toyota says 100k and Denso says 30k. I frankly think the ones replaced appear to have many more miles in them, but the new ones were begging to be installed. I learned something. Hope this thread will be helpful to the inquisitive.
     
    #14 ufourya, Jul 14, 2014
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  15. UoD

    UoD Junior Member

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    I hope this isn't a stupid question -- but, it's been over 15 years since I have had to change plugs on a vehicle. This looks like a simple car to change plugs on, so I want to do it myself instead of paying the $250 that the local shop just quoted me.

    Anyhow --- my question is : Do I need to gap the DENSO 3485 plugs? I didn't see anything in the writeup above about that. Or -- are they pre-gapped?
     
    #15 UoD, Dec 15, 2015
  16. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    The plugs should definitely be pre-gapped, you shouldn't have to touch that. Some manufacturers even caution against trying to fine-tune, adjust them further.
     
    #16 Mendel Leisk, Dec 15, 2015
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  17. UoD

    UoD Junior Member

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    Just changed them out over the weekend. If you ignore the 10 minutes it took me to run down to Home Depot to get a pair of really long needle nose pliers (socket got stuck on the plug and came off of the extension ... forgot to tape it first :) ), the whole job took me about 20 minutes. Thanks for making this thread @ufourya .

    My wife's 2012 Prius C was at 120,500 when I did the change out on Sunday. Plugs came out without any effort, and everything looked surprisingly clean. She puts about 54,000 highway miles on this thing every year , and I am trying to do my best to keep this thing running to at least the 250,000 mile mark. I know with fluids (engine and inverter coolant), they say to change them out more frequently after the 100,000 mark. Is there any reason I should do the same with the plugs? Or, is the recommended 125,000 interval still good for these? Like I said -- the plugs I took out didn't look too bad at all.
     
    #17 UoD, Dec 22, 2015
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  18. Mr Incredible

    Mr Incredible Chance favors the prepared mind.

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    I always check sparkplugs even though they're pregapped. Just to be sure. The little coin shapped gap gage is the type I like.
     
    #18 Mr Incredible, Dec 25, 2015
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  19. Oldwolf

    Oldwolf Prius Enthusiast

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    This is a very informative thread. I have 81k on my C, the car is running fine so will wait until I hit 100k I guess.
     
    #19 Oldwolf, Aug 14, 2019
  20. Talha Maqsood

    Talha Maqsood Member

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    Very Informative thread I have 67K on C, i think i will wait for 100K ;)
     
    #20 Talha Maqsood, Aug 22, 2019
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