One of the Worst Selling Points, New Vehicles

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quote:
Originally posted by Bamaro:
Question, if they go for 100k with no signs of wear, what then is the benifit of changing them?
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The plugs are really "lifetime" parts from what I understand, as the interval is really picked for EPA purposes anyway. For one, the Toyota 2.4L engines contain the Iridium plugs and spec a 150k service interval.

The platinum plugs with platinum pads on BOTH the ground and center electrodes, or the Iridium plugs with an Iridium center and a platinum pad on the ground electrode last virtually forever (theoretically) if there isn't any extreme fouling.
 
my wifes Malibu has these 100,000 mile plugs. but when I pulled them at 50,000 miles. I noticed that the nipple on some of the arms was worn completely off. the car runs smoother again after changing them. I just cant see going that long. glad my truck takes copper plugs. cheap and I change them every 30,000 miles.
 
on a lot of motors, if you are going to go through the trouble of regapping the plugs every 30k miles, you might as well just put in new ones. anyone who has done plugs on a f150 or expedition with a 5.4L knows exactly what i mean. and a good set of platnium plugs costs at most $12 a plug, thats not that much.

on my car i run the copper version of the OEM plug and replace them every 15k miles. im super anal retentive about my car though. the plugs are about $1 when i buy them from my works supplier. plus i drive my car really really hard on the street, so its good for my worriesome side to get in there and check everything out. my car has about 122k miles on it now, and ive had it since 95k miles and changed out the plugs 2 times.
 
My '01 Accord came with NGK double Plats (Both center and ground electrodes have plat). I changed them for the first time at 102K and the gap and condition of the plugs was perfect. In fact, they're in the trunk as an emergency backup. At $12 a pop, they are expensive, but can last a very long time in a properly running engine.

I went cheap with my replacement plugs (NGK copper V-power) and have replaced them after 40K.
Alls good, the performance is the same and no degradation of MPG that I can detect.
 
Question, if they go for 100k with no signs of wear, what then is the benifit of changing them?
 
quote:
Originally posted by Bamaro:
Question, if they go for 100k with no signs of wear, what then is the benifit of changing them?
Click to expand...
There isn't one.
In the OLD days, spark plugs had to be changed often because of leaded gasoline. Every 20,000 miles was about the max they would go, covered with lead ****.
 
They won't do 100k without wearing, just not possible...
The ground electrode loses electrons every time it sparks, that's what a spark is, electrons jumping a gap...

Platinum plugs are for lazy people.
 
quote:
Originally posted by gtx510:
They won't do 100k without wearing, just not possible...
The ground electrode loses electrons every time it sparks, that's what a spark is, electrons jumping a gap...

Platinum plugs are for lazy people.
Click to expand...
So are Iridium plugs a better option to use? The reason I ask is after looking at sparkplugs.com, the OEM NGK for our `02 325iT is platinum but costs more than the Iridium NGK. BTW, we basically have the same motor (M54).
 
quote:
Originally posted by gtx510:
The ground electrode loses electrons every time it sparks, that's what a spark is, electrons jumping a gap...
Click to expand...
That's also why new speaker wire sounds so much better: the old ones had run out of free electrons. By chance are you a quantum mechanic?
 
My owners manual says not to change the plugs until 100k. I have no such plans to even look at them until 100k, at which point I will buy new ones and then replace them. I would surely think with todays technology a spark plug could be designed to last 100k without losing its gap to the point gas mileage would suffer.

I guess if you do extending idling then in theory the 100k mark would be hard to achieve, but then all your maintenance intervals would have to be shortened for this type of harsh service.................
 
For most of the last 40 years, I have been able to buy AC sparkplugs for about a buck. I never put a used one back in. Now that buck sparkplugs have gone the the way of buck gasoline, I still think I will splurge on 4 new ones when my Cavalier hits 100K. Won't be looking at them in the mean time.
 
New, sharp, old fashioned, steel tipped spark plugs have less resistance to fire than platinum tipped ones. They work great when new. Iridium is better, though.
Mfrs. use platinum for the mandated long change intervals, for emmissions legalities.
 
O.K. Gotta bite on this one. My understanding is that the 'current', i.e. electrons travel along a path. When they 'Jump' across the gap of the plug, its just that.. it's a jump on thier merry little way. These aren't electrons being 'sucked' out of the tips of the plugs? I'm I missing a really big joke here or what?
 
I think the recommended interval on my 92 grand Am was 30 K. I faithfully changed them, but they never looked worn or the gap opened. I never saw any difference after changing them. I don't expect to see much difference when I change the ones in my Cavalier. At 80 K, I am still getting well into the 30's on gas.

Since modern coil packs use both ends of the coil to fire 2 plugs, does that mean the other one gains electrons every time it fires? Will I take them out and find 2 of the plugs have the gap almost closed up?

With all the problems of stripped threads people have, I wonder if unnecessary messing with the plugs is a good idea. As mentioned early in this thread, the plugs are treated to come out after 100 K.

Over the years, sticking to what is actually needed and avoiding unnecessary messing around has served me well.
 
The arc causes the electrode material to erode.

I guess it could be a joke in that the electrode material is made of atoms that contain electrons.
 
Wow, people need to learn more about electricity. A spark jumping does NOT leave a deficiency of electrons on one electrode and an excess on the other.

You can think of voltage as pressure. Let's say you have a pool of water, and you're pumping that water through a hose. When there's enough pressure, that water will come out of the hose and go back into the pool. That doesn't mean that all of the water is leaving the hose, it means that there was enough difference in pressure from the pump for the water to squirt out and return to the pool.

Plug gaps widen because the HEAT created by the spark jumping vaporizes a small part of the electrode. Platinum and Iridium don't vaporize as easily as copper.
 
I concur with Scimmia as well.

The way I learned it when I got my ELECTRICAL ENGINEERING degree was that it was like playing a game of hot-potato. The atoms passed the electrons, not permanently giving up their electrons.

That's not to say there are not other things happening thermally or chemically that encourage chemical reactions that erode the electrode. But the mere passing of current doesn't make the copper or platinum or whatever metal disappear.

Think about it for a moment. If this were the case, then how do large power lines remain in place for years. They pass far more current than speaker wire or spark plug wires, yet you don't see them "evaporating" because all the free electrons are gone.

People, put your thinking caps on!
 
quote:
Originally posted by Scimmia:
Plug gaps widen because the HEAT created by the spark jumping vaporizes a small part of the electrode.
Click to expand...
I think there's more to it than that. As I recall, the negative electrode shows more erosion than the positive electrode. This is why single-platinum spark plugs do not work well in distributorless waste-spark ignitions, but work well in distributor and coil-on-plug ignitions.

[ August 25, 2006, 12:05 PM: Message edited by: brianl703 ]
 
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