How often should spark plugs be replaced?

Discussion in 'Motorized Vehicles' started by narsnail, Jul 5, 2009.

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  1. narsnail

    narsnail Notebook Prophet

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    well its done, no problems :) one plug was in kinda bad shape, was much darker than the others, but other than that they were in pretty good shape.

    it runs a bit smoother now right past ignition, no funny idle, and it feels a bit more torquey, i jumped from a .54 gap to a .56, but other than that feels a bit smoother.
     
  2. allfiredup

    allfiredup Notebook Virtuoso

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    I've been waiting until at least 100k for the last 10+ years. My older Hondas recommended every 60k...along with the painfully-expensive timing belt change! Timing chains are a beautiful thing (from a financial POV, at least)!
     
  3. K-TRON

    K-TRON Hi, I'm Jimmy Diesel ^_^

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    What are you talking about.
    No need to change them. The mechanics say so because they want to suck your money for something which does not need to be changed.

    My dad never changed plugs in his 87 Jeep, and neither has my brother. They still perform like new.
    A clean running engine would yield very low carbon deposits in the head, thus no junk buildup in the plugs recessed area.

    You can think what you want bud, but they do not have to be changed.
    A good plug will last until it is physically snapped.

    Diesel fuel injectors are a complete other story. My DD manual recommends re manufacturing after 800,000 miles


    K-TRON
     
  4. flipfire

    flipfire Moderately Boss

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    Im with Kevin on this one

    Even on a optimal tuned engine the electrode on spark plugs wear down eventually till you start noticing the problems. It will give you weaker spark ignition thus bad fuel efficiency.

    Have quick read at this, http://www.aa1car.com/library/cm1196.ht
     
  5. K-TRON

    K-TRON Hi, I'm Jimmy Diesel ^_^

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    If electrodes go bad, how come the old Mack AC-1's and Model Fords from the early 1900's still run on their original plugs. Huh.

    A good cleaning of the plugs and gap checking is recommended every so often, but a good plug never really have to be replaced.
    Some of the new plugs may be of very low quality where they need to be changed. But a good plug pre 1990 will last forever. Especially the commercial grade ones. I have some over 60 years old which run better than any new plugs I put it. I will upload images in the morning
    You guys are getting sucked into advertisements

    K-TRON
     
  6. allfiredup

    allfiredup Notebook Virtuoso

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    I remember a friend of mine in high school trying to change the plugs in his Mustang ('84 model, if I recall). He managed to break one of the plugs off trying to remove it...then he stripped it out trying to get it out! It was a nightmare....lesson- if it ain't broke, don't fix it!
     
  7. dietcokefiend

    dietcokefiend DietGreenTeaFiend

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    I can show you quite a few plugs from my collection as well. I have some that were fouled from fuel, some super high mileage where the spark started to consume part of the electrode, and others that were heat cycled enough that the ceramic cracked. Copper plugs and some fancy platinum/iridium plugs wont last forever under "normal" usage. Cars age, cars start burning a bit more oil as the rings wear, and you get a fouled plug. Technically you could readjust the plug and sand blast it every oil change to keep it like new, but why? Same could be said about sharpening disposable razors with the sandpaper on the front of free match boxes. Yea it works... but why.

    NGK copper plugs (some of the best) cost about $1.40. Most are rated for 15-30k. Iridium plugs used in a few newer cars are spec'd out to 100k. On top of it, it is the manufacturer saying to replace them at various intervals, not the spark plug companies. It is not a vast advertising conspiracy, unless you are one of the types that gets con'd on those twin spark super spark plugs with capacitors and elfs inside.

    Spark plugs are one of the cheapest parts someone can replace on a car. Heck on my new car the spark plugs cost a fraction of what required 502.00 the oil costs.
     
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