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Take a look at this spark plug . . Need Opinions

BlackRock

NAXJA Forum User
Location
NorCal
Hi All,

Did a tune up today, been getting bad gas mileage lately so new plugs, rotor and cap. Usually when I pull my plugs they look fine, however, this time I see what appears to be rust! Is this a blown headgasket or cracked head? Or? Hasn't been overheating and it has never been overheated to the point where damage could occur in the past 5 years. Like I said, the plugs usually look great, but not this time, all 6 looked like this. :(

Any opinions?? Much appreciated.

6t03yc.jpg
 
Well its not rust....

Where are you getting gas from regularly? That looks like buildup from some kind of additive in the fuel.
 
First rule of fight club--never talk about fight club.

First rule of NAXJA--always post your BASICS--year, engine, etc.
 
First rule of fight club--never talk about fight club.

First rule of NAXJA--always post your BASICS--year, engine, etc.

Can't believe I forgot to do that ;\ . . Thanks :flipoff:

89" Cherokee Ltd. 4.0 Renix, NP242, 4" RC Lift, 33" Tires, Underarmour, Roof Rack, etc. 199k Original Miles.

Well its not rust....

Where are you getting gas from regularly? That looks like buildup from some kind of additive in the fuel.

Just Valero (USA) pump gas 87 octane. Have not run any additives lately. Thx
 
Well its not rust....

Where are you getting gas from regularly? That looks like buildup from some kind of additive in the fuel.

Agree.

Looks like you are running ARCO gas.

Or something else with a weird additive in it.

Consider running some BG44K through the full system and change brands.
 
Color looks fine. Black would indicate too cool of a plug. White: too hot.
Tan is a good color. Are the plugs new as well? If they're older plugs you,
will have some buildup like that.

Ya, just saw that they are new plugs. I'll go with the fuel issue consensus.
 
Last edited:
Looks like "ash" deposits.

Fuel additives can cause this, but you mention that you aren't running any.

No mention of how many miles are on these plugs.........?

I would try swapping in a new set of plain old Champion coppers. Gapped to .035. Switch the brand of gas you run, then check the plugs, or at least one or two of them after a few weeks to see if it repeats.
 
Looks like a buildup from additives, or are you losing any anitfreeze?

Could be a leaky valve guide combined with running lean.
 
Looks like a buildup from additives, or are you losing any anitfreeze?

Could be a leaky valve guide combined with running lean.

Could be, but when I re-read his post he says all six plugs are like that--not likely a head gasket.

I'm figuring crap fuel.
 
Plugs look a little cool as well.
 
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