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Old 06-13-2016, 12:45 PM   #1
Oberon67
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Wore-out Old Spark Plugs

So Saturday I replaced the spark plugs in my '81 C10 with the 250 inline six. Here's what they looked like... that's cylinders 1 through 6 from left to right.





Now I know that a dry, light-brown deposit means normal operation... but there are limits!

Truck is running somewhat stronger now at low revs, thanks to six new AC/Delcos.
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Old 06-13-2016, 01:23 PM   #2
storm9c1
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Re: Wore-out Old Spark Plugs

Excessive ash deposits? Is it burning oil? Or using fuel additives? How many miles are on these plugs? I don't see significant electrode wear which leads me to believe these plugs don't have as many miles as the deposits show...
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Old 06-13-2016, 01:36 PM   #3
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Re: Wore-out Old Spark Plugs

"How many miles are on these plugs?"

I don't really know, and have no way to find out. These plugs were what was in the truck when I bought it a few months and 2000 miles ago.

The truck uses a little oil, to the tune of maybe a quart a month. I check it when I get gas. I'm not certain how much is being burned and how much is leaking; I know a little bit is leaking because you can see a little seepage at the oil pan gasket.

I'm not using fuel additives. I am burning 87-octane regular gas with ethanol.
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Old 06-13-2016, 04:07 PM   #4
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Re: Wore-out Old Spark Plugs

Keep an eye on the new plugs and see what the coloration changes to as you put more miles on. My 305 V6 in my GMC burns a bit of oil. Mainly on a hot start up it will smoke a tad and then it's fine. Plugs are burning really clean though. I think mine burned a quart over the duration of 8 months. lol Might try some thicker oil....maybe 15W-40 Rotella and a can of Engine Restore. I did that and it brought the compression up on my old 292 around 20 pounds!
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Old 06-13-2016, 04:29 PM   #5
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Re: Wore-out Old Spark Plugs

Quote:
Originally Posted by Oberon67 View Post
The truck uses a little oil, to the tune of maybe a quart a month. I check it when I get gas. I'm not certain how much is being burned and how much is leaking; I know a little bit is leaking because you can see a little seepage at the oil pan gasket.
With the looks of those plugs, I'd say most of that "lost" oil is being burned. Check those plugs again at the next oil change and see how they look. We need to find out how rapidly the deposits are building up.
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Old 06-17-2016, 01:19 AM   #6
mike16
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Re: Wore-out Old Spark Plugs

thats nothing. i finally replaced my '90 camry's origonal plugs after 235k miles. the dealer wanted to keep some for thier wall of shame. my rotor and distributor cap too.
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Old 06-19-2016, 07:50 AM   #7
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Re: Wore-out Old Spark Plugs

You may want to consider where you buy your gas . There is a reason those places are .05 cents cheaper . They do not put the same additives or any in there fuel the keep things burning clean . I had similar looking plugs ( fuzz looking) and went to a major fuel maker and I did not have that problem again .

The P.O. may have been burning the cheap gas .
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Old 06-21-2016, 03:05 PM   #8
Oberon67
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Re: Wore-out Old Spark Plugs

Quote:
Originally Posted by homemade87 View Post
The P.O. may have been burning the cheap gas .
I consistently put either Shell or Citgo gas in it, and very rarely a tankful of Exxon. I buy my gas on gas-station credit cards, so I'm reliable about that.

Dunno what the guy before me was using.

There is the possibility that these deposits are from burning oil. Oil consumption is low, as I mentioned, but it is using some and at over 100K miles now there could definitely be some getting past the rings. There's no smoke in the exhaust at all, but this truck is new enough to have a catalyst so a little bit of smoke out of the motor would get cleaned up by the time it got to the tailpipe.

The engine runs so well at present I see no need to do a ring job. I'll just put a quart of oil in it a month and drive it.
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Old 06-22-2016, 01:37 PM   #9
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Re: Wore-out Old Spark Plugs

if this is a lightly used truck like less than a tankfull a month you may want to search out a station that provides nonethanolgas and try that for a few months
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