The oddball spark plug

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M

MN Driver

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Apr 5, 2005
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I did a compression test on my 1.8L 7AFE Toyota engine that I have on my 95 Geo Prizm and when I took out the spark plugs I noticed one odd ball that didn't look quite like the rest.

Take a look at these pics and let me know what you think.

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The plugs in this engine all look like this one except this is the only one with the 'white dust' on it. All images are of the same plug. The plugs in the engine have between 5,000-8,000 miles on them. Two of them seemed to have a reddish appearance to them.

My driving has been over 90% highway for the past 3,000 miles and the car consumes a quart of oil every 1,000 miles or so with no coolant consumption.

I'm looking to replace these with platinum plugs the next time around.

Two questions:
What is this white dust?

and

Does this plug look like it would be better replaced by a plug that is one step colder in heat range?
 
heres a pic of mine, you'r looks the same except for the white crusty deposits... what that is i have no clue

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btw nice close-up macro shot, as you can see i can't do the same.
 
My camera has a macro mode that seems to do the job nicely. Try holding the camera away from a small object and then slowly bringing it closer and you will get the best close up shot, just remember to keep the desired focus point in the center so the camera adjusts properly.

While I'm off topic, my compression readings were all between 180 and 190 at the fourth compression stroke. 141 is the minimum limit and 191 is the factory standard pressure. I thought I would have found different numbers because the thing seems to have almost no engine braking even in first or second gear.


This spark plug is from the third cylinder if it makes any difference.
 
There are some places on the web with pictures of common spark plug problems. The only I can find now is http://www.fizzer-redline.com/plugs.htm.

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Ash Deposits

Light brown deposits encrusted on the electrodes and insulator, leading to misfire and hesitation. Caused by excessive amounts of oil in the combustion chamber or poor quality fuel/oil.
 
These are white deposits that I saw are as white as paper, whiter than white on my computer screen, not silver though.
 
I just found one of my answers. These Autolite 3923 plugs that the previous owner put in this engine are a heat range hotter than the recommended plugs.

I checked the cross reference and it comes out to an NGK BKR6EYA when the specified plug is a BKR5EYA. I thought the fact that the ground strap shows more than half of the lightened portion was an issue.

To the correct heat range in a platinum plug I go!

I'm still curious about the white dusty stuff though...
 
We have 10% ethenol gas here throughout the year, I suppose it is either that or an additive in the oil that is leaving the white dust. I probably shouldn't be worried about it, but it just seemed strange how all the rest didn't have this, and also a little more strange that it only appears on one side of the plug.

I also just found out that I'm mistaken, NGK plugs are higher numbered with the colder they get, so apparently the previous owner was already running a step colder than the stock plug so I would have bought the same plug essentially, except I'd rather go with a platinum plug.

How long does the average copper last, 30k miles? and platinum about double that?
 
Coolant leaking into the combustion chamber can leave a white deposit on the plug. It could also explain why the plug is only white on one side, the side facing the leak.

30k is maybe a little high for copper. Plats will do 60k, maybe more if your engine, ignition system and fuel go easy on them.
 
quote:
Originally posted by MN Driver:
I just found one of my answers. These Autolite 3923 plugs that the previous owner put in this engine are a heat range hotter than the recommended plugs.

I checked the cross reference and it comes out to an NGK BKR6EYA when the specified plug is a BKR5EYA. I thought the fact that the ground strap shows more than half of the lightened portion was an issue.

To the correct heat range in a platinum plug I go!

I'm still curious about the white dusty stuff though...
Click to expand...
With NGK plugs, as the number get larger the plug gets colder.

http://www.ngksparkplugs.com/techinfo/spark_plugs/overviewp2.asp?nav=31000&country=US
 
I'd use $2 NGKs copper until you hit the right heat range since you'll be taking them out again to check anyway, may switch and the copper work better over their 20K life than plat.
 
Here's overheated - plug too hot's description

Chalky white insulator with little or no coloration and extensive electrode wear which is possibly blistered or pitted. The shell may also be discolored from light gray to a dark blue, almost black.

Probably my first choice to fix would be - normal heat range NGK plug.
 
If you are burning one quart in 1000 miles with that tiny engine, you have big oil control problems, and will show up on the plugs.
Maybe the previous owner put the hot plugs in to burn off the oil deposits, and you will foul with standard heat range plugs.
 
If changing plugs is easy, that is they're accessible, here's another vote for NGK copper plugs. I wouldn't worry about that small amount of deposit for the time being on a 10 year old vehicle.

Like suggested, put in new coppers of correct heat range and inspect again in 5k miles.
 
I'd definitely go with NGK BKR5EYA. Platniums would likely not run as well.

My Corolla always has an oddball plug as well, from cylinder number 3. Comes out with hella carbon on it. Actually, all my plugs look about like the one your showing except 3!

The oil consumption; well, 1 quart/ 1000 miles is fairly normal in a high mileage 7AFE/4AFE, especially with highway driving. My car was the same way like I was telling you MN Driver but now all of a sudden the consumption has practically stopped! The oil that did it? 5w-30 Trop Artic. Wierd. I think the engine/rings etc. also are finally 100% cleaned out from Auto-RX and all the highway driving I do. My car has insanly strong engine braking. After the 1st Auto-RX cycle, the engine braking became much stronger.
 
quote:
Originally posted by mechtech:
If you are burning one quart in 1000 miles with that tiny engine, you have big oil control problems, and will show up on the plugs.
Maybe the previous owner put the hot plugs in to burn off the oil deposits, and you will foul with standard heat range plugs.
Click to expand...
quote:
Originally posted by m2200b:
I'd use $2 NGKs copper until you hit the right heat range since you'll be taking them out again to check anyway, may switch and the copper work better over their 20K life than plat.
Click to expand...
quote:
Originally posted by ex_MGB:
If changing plugs is easy, that is they're accessible, here's another vote for NGK copper plugs. I wouldn't worry about that small amount of deposit for the time being on a 10 year old vehicle. Like suggested, put in new coppers of correct heat range and inspect again in 5k miles.
Click to expand...
They are actually a step colder plug, I made a mistake in not realizing that the NGK plugs are a higher number with a colder plug, which is opposite of domestic plugs. This was the cylinder 3 plug, I don't know if I mentioned that or not, so I suppose we've got a bit of a similarity there, probably something to do with engine design. I think I will go with the same plug heat range that is already in there which is the stock plug in some places that you look and other places it is one heat range warmer. It seems that the recommendations over the years from Toyota go back and forth quite a bit. Since nearly over 90% of my driving is highway and I rarely have short trips or much idle time at all, I think I will stick with the cooler specified plug. This plug looks like it was scorched a bit at only 5k-8k miles on it so I am really not looking to go any warmer, but I might just change them out when I change my oil next which should be 10k miles tops on them and then I'll see what shows up. By the way they are a pretty easy change out, just pull the boot from the top of the engine and pull a second 6 inch boot that goes down to the cylinder and then use an extension on a spark plug socket to get it out, it's pretty easy after I figured out the right way to get the long plastic boots loose. I suppose I was a bit concerned over nothing with the deposits because for all I know they are from some additive that the former owner used in his gas.

I'm curious why the coppers are the first choice and platinums the second choice? It seems that all of the automakers have gone to platinums and soon they will probably be pushing iridiums mainstream? I probably will go with copper since you guys suggest the NGK's but I am just curious as to what the difference really is?

I suppose I should mention that the oil burning is nearly non-existant off the highway but since I run the car on the freeway for an hour or so at the freeway speed limits which in Minnesota go up to 70 mph(or faster in order to keep up with traffic) nearly every time it gets driven, I'm sure the oil gets mighty hot in that little crankcase which is just shy of 4 quarts. I'm going to try a thicker oil, 15w-50 Mobil 1 for the first OCI of this summer to see what that does to consumption, if it is still pretty bad then I might be giving Auto-Rx a shot.
 
Copper conducts better than Plat. It is a softer metal so the sparking causes quicker wear of the softer metal and less miles of peak operation.
Plat deal best with hard to pull locations like the typical transverse v6 by giving extended service life. Irridium more of the same. A case can be made that the Plat plug is more cost effective like syn but you need to leave them in 2X to shift cost savings to Plat. I use either on my Mazda 4 and daughters Tercel but like the copper better. Don't use two tip or four tip Bosch Plat - they don't perform or last as well as NGK or Denso.

Since you do your own, their easy to do, and you will be pulling them annualy anyway I'd use NGK V Power copper.

I assume you did the wires too but would on a newly purchased used car.
 
just pulled the bosch supers on my civic and put in NGK zfr5f-11's v-power, and it seems to have a little extra pep and idles smoother, i dunno... NGK +1.... don't know if they are copper or plat or what though
 
V power I believe are copper plugs. as what alot of people use in their 4.7 dakotas. beings we have a coil over plug. it says not to use plats. so alot of people have fell in love with the NGK V Power plugs. over the champs and autolites. always thought NGK made some of the best plugs around.
 
I wouldn't worry at the first step. It is not oil fouled. I had green plugs once... years later I learned some gasolines may leave an avocado green tint.

The problem here is that no plug look exactly like the other so the sample photos are ambigious for reference at best. Here's a NGK handout from '77 a guy scanned which has 29 photos. With the variances between the "goods" I wouldn't hooked up too much with the how white it is, so I tend to resemble it with no:17
 
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