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Old 02-21-2001, 09:45 AM
72wag 72wag is offline
Join Date: Jan 16, 2001
Location: Bellevue, WA
Posts: 173

Ok, so i changed the spark plugs today just because it was a cheap thing to do on the old beast. a while back i was having overheating problems and it took me a while to get around to fixing the water pump, which had grenaded on me. anyway, cuz of that my engine ran REALLY hot for a while. i think this killed my spark plugs because when i pulled them this afternoon, the arm(?) that goes over the tip on each plug was almost totally white and looked very brittle. on a couple of the plugs there was quite a lot of carbon deposits(i think, well, at least a lot of black powdery looking stuff) in and around the tip and on some of the threads. there was also a little bit of what looked like oil on the threads of some of the plugs. not enough to make it look like it was dipped in oil or anything, but there was a little bit.

So, does anyone know if there is anything to tell about the condition of the engine by the condition of my spark plugs?

what i'm thinking is that i fried 'em by driving it really hot for a while. now that is solved cuz of the new water pump and thermostat. its got plenty of oil in it. everything else seems to be up to par. i just don't know what the condition of hte spark plugs really means. any help would be greatly appreciated.

BTW, it ran a lot stronger with the new plugs(standard Champion Truck plugs @2.50/each)

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Old 02-21-2001, 10:15 AM
bgwagoneer bgwagoneer is offline
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Join Date: Jan 24, 2001
Location: Fayetteville, NC USA
Posts: 8

look in the back of any Haynes manual and it has a color chart that shows 12 different messed up plugs and what caused the problem with that particular plug. good luck.
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Old 02-21-2001, 12:21 PM
nograin's Avatar
nograin nograin is offline
304 AMC
Join Date: Dec 19, 2000
Location: Philadelphia, Pa., USA
Posts: 2,093

Good advice to look at the pics, but your description is pretty good also.

The oil on the threads is prob a bit of oil. By itself, my guess is no big deal.

The dry black is carbon deposits from running too rich. Enough of that and it is very hard to get the engine to run good.

Now, the interesting thing is the white tips sound like you were running lean. It is possible that when the wate pump went, the heat transfer in the pistons changed enough that the combustion itself ran hot.

It is also possible that at some point, even with the water pump fixed, you run pretty rich, and under other conditions you are running lean.

If all the plugs were similar. Then the thing to do is to check one or two on a periodic basis.

A real race type techie would say check them after using them a specific way.
that is. idle the engine from cold and check them, then idle the engine warmed up and check again. then run it a wide open throttle, put in neutral on the coast down, and check it again, and then do same for part throttle. Then, in theory you will have isolated the conditions.

Certainly easier to just use it, and see if those conditions crop up again. The start to figure it out if there is definately a problem.
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Old 02-21-2001, 12:44 PM
72wag 72wag is offline
Join Date: Jan 16, 2001
Location: Bellevue, WA
Posts: 173

thanks for the email and the tip, i'll check out my chiltons to see if it has the same thing.

now that i think about it, when i first got it, like a year ago, i thought the mixture was a little too lean, so i thickened it up, but then it smelled too rich so i changed it after a while, and then THAT'S when all these things started going wrong with it!!! i bet that was the problem. i'll have to double check the carb settings.

thanks you guys,
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