117,000 Mile Spark Plugs

[Chispas]

It started last fall when the price of gasoline
went over $3.00/gallon....

A neighbor that helps me (and I help him) said that he was close to 100,000 miles on his sparkplugs, they needed to be changed. I agreed, and offered to help if he needed it.

He showed up yesterday with a new set of sparkplugs and asked if I could gap them and tell him anything he needed to know. (He's 43 years-old and never learned....amazing !) It
ended up me me being the instructor, him the
wrench twister. Vehicle is a 2001 Dodge 1500
with the 5.2 liter, and 192,000 miles.

When the price of gas got high last year I'd
already talked him into adding 3 oz. acetone
per 10 gal. gas to help on his gas mileage.

The old plugs showed perfect color. They were
extremely clean! But, they averaged about
1/10 " gap....really wide.

He swore that there had been no missing of
the engine or any signals that the plugs were
getting tired.

I was impressed, No. 1 - how clean the plugs were,
No. 2 - how they had not malfunctioned with such
a wide (worn) gap.

Don't remember the number on the plugs, but they
were Champion platinum.

I'm beginning to think that the acetone was
the answer to most of what was so impressive.

Anyone else had a similar experience with acetone
usage ?

 

[wavinwayne]

I think changing spark plugs is over-rated, if the engine is otherwise healthy.

Last fall, I replaced the OEM plugs & wires in my wife's '97 Expedition. They had approx. 110k miles on them. Like your friend's case, the gap on the used plugs was too wide, but the color was good.

After I installed the new plugs & wires, I could not tell any difference whatsoever in the performance of the Expy. I probably could have run those plugs for 150k miles without any problems.

 

[Chispas]

Wavinwayne, thanks for the comparison....

My only 'add' would be to warn owners of any
vehicles with aluminum cylinder heads, they must
still practice periodic removal and always apply
anti-seize compound....

Aluminum heads are notorious for welding sparkplug
threads....

Any sparkplug in an aluminum head for 100,000
miles just MAY NOT unscrew without taking the
aluminum threads with it....

 

[jamesn]

i had a toyota corolla that must have had that happen to it. it had 3 regular spark plugs and 1 that was for a ford v8. it had been bored out and tapped. it ran fine though. kinda wierded me out at the time.

 

[Korean_redneck]

THIS THREAD IS USELESS WITHOUT PICS!!!!

 

[glennc]

I agree with wavinwayne. I've never been much for changing plugs, and wheneve I have finally gotten around to it, I have not once noticed a difference.

Maybe some engines are more sensitive to it, but apparently none I've owned.

I am a big believer in copper anti-sieze on plugs in aluminum heads, though.

- Glenn

 

[Dave Hess]

Wavinwayne,

On some cars, like my wife's 98 Civic EX, I can definately tell when it needs new spark plugs. Gas MPG will drop slightly.....no matter how new the air filter, fuel filter, PCV valve, cap & rotor is. With new NGK copper plugs (which are only good for 30K miles) gas MPG will go from 35 MPG to 37 MPG. I know its not a BIG increase, but the cost of new plugs ($7.00) are worth it in the long run

I agree 100% with you that the factory installed OEM Platinum spark plugs can easily last 100K miles.

 

[ricks]

I too had a 99 Expedititon. It had 150,000 miles before I decided to change the plugs. It did not run any better after. My wifes '98 Buick Regal had 120,000 miles on it when it started missing. Changed the plugs and ran perfect.

 

[The_Jeff]

Wide gaps actually fire lean mixtures better because there's more likely to be an ignitable molecule between the electrodes. It's only when the gap gets so wide the coil can't keep up that you have problems. The spec you gap to is a service minimum that the manufacturer expects to grow a little bit. In a low-revving truck the coil has plenty of time to recharge.

 

[Jim 5]

Chispas makes an excellent point. Really worth remembering for owners of asian and german cars.

One thing to add with respect to spark plugs and aluminum heads. USE A TORQUE WRENCH to apply final torque after applying anti-sieze and finger-tightening as far as possible.

 

[unDummy]

Platinum/iridium really have added long life to plugs. They can last forever. Just clean, regap, lube, and reinstall. Reuse until there is no platinum left.

Don't forget that engine type and driving style do much for plug life.

 

[warrior pilot]

I remove my plugs every 50 hrs of operation and clean the lead out per the service manual. Sometimes the lead nearly touches the gap ! Thats what we used to deal with before unleaded gas.
What is the torque value for a toyota corolla spark plug ?

 

[GoldenRod]

With today's high energy ignitions, a .060" gap is not uncommon. Just a reminder, iridium plugs are not supposed to be gapped. If they are not within specs, you take them back.

 

[oilyriser]

Will a large gap wear out the wires sooner, because of the high voltage needed to jump the gap?

 

[The_Jeff]

If your wire insulation degrades that spark will find its way through a crack to ground sooner. Path of least resistance applies. Insulation degradation is a function of underhood heat, ozone...

 

[toocrazy2yoo]

quote:

---

If your wire insulation degrades that spark will find its way through a crack to ground sooner. Path of least resistance applies. Insulation degradation is a function of underhood heat, ozone...

---

And oil-soak under the lid on the cam-cover..Dammm spark plug tubes are tough to seal perfectly!

 

[unDummy]

Iridium plugs can be regapped. You just need to do it correctly.
I check and gap, as needed, every plug that I touch whether new, or old being reused.

I lied. My Mercury marine motor and Mazda rotary didn't have plug gaps to worry about.