ugly spark plug

DeftwillP · Oct 12, 2008

So I'm changing out the plugs on my 99 that I just purchased a year ago. It feels like the first 3 plugs are stripped because they'll barely tighten but its not that bad of a problem I guess. I'm going with RC12ECC champions which i've always used in my other xj aside from ngk.

All the plugs I pull are the same kind and in decent used shape except for the 3rd cylinder. I really had to work to get the boot off but once I did, I found this:

Anything I should worry about here?

wycowboy · Oct 12, 2008

Yeah, there might be. It appears that you may have, or did in that past, have some coolant gong into that cylinder and being burned. That looks just like the plug I pulled out of the head on my 89 Tbird 3.8 when it was burning coolant in the #3 cylinder.

Chris

Cody90XJ · Oct 12, 2008

Wow that doesn't look good but, I guess you already knew that our you would have posted it. Did it run poorly? When was the last time you did a tune up? Any other proublems like coolent consumption? I would replace the plugs, wires, cap and rotor. If the proublem presist then did it into it further.

DeftwillP · Oct 12, 2008

It's been running pretty well actually. I feel a very slight hesitation on the highway, and I mean extremely slight. It's on 6" of lift, 4.56's, and 32's bfg at's. I'm getting around 17+ on the highway even with a cracked header.

I just purchased this last year and supposedly the engine was replaced within the past year (the engine is painted baby blue from pan to valve cover). This is the first time I've removed the plugs so I don't know the history with them or even the engine itself. I was going to get a new cap/rotor set at az but they only had ones w/o brass contacts. I just used my dremel and polished all of the contacts on mine and blew it out good.

Saudade · Oct 12, 2008

You should check the compression on it.

Cody90XJ · Oct 16, 2008

I agree check the compression on it when you can. I would also pull the plugs out after a 1000 or so miles and take a look at them all to see is there are any differences between them.

DeftwillP · May 7, 2009

So, I've been having this ever so slight hesitation and stumble while at idle. I decided to pull the number 3 plug since thats where I had an ugly one last time. This is what I found on plugs that barely 7 months old(maybe a few thousand miles):

stewie · May 7, 2009

eewwww. looks like the same problem is persisting (obviously). any codes being thrown? have you checked the engine with a block tester? is there oil in the coolant or disappearing coolant?

DeftwillP · May 7, 2009

I figured that it was the same problem as well, just hadn't gotten as bad yet. I don't know what a block tester is.

According to the pics in the back of the haynes manual, it looks like oil is getting past the rings. No measurable amounts of oil or coolant being lost.

joe_peters · May 7, 2009

"This plug has ash deposits which are light brownish deposits that are encrusted to the ground and/or center electrode. This situation is caused by the type of oil used and adding a fuel additive. This condition will cause a misfire. This can be also caused by changing oils in midstream."

Quote from: http://www.theultralightplace.com/sparkplugs.htm

88 Wagonman · May 7, 2009

joe_peters said:
"This plug has ash deposits which are light brownish deposits that are encrusted to the ground and/or center electrode. This situation is caused by the type of oil used and adding a fuel additive. This condition will cause a misfire. This can be also caused by changing oils in midstream."

Quote from: http://www.theultralightplace.com/sparkplugs.htm

Those charts are for 2-stroke engines and are only somewhat applicable.

My vote is coolant. As stated above, check the compression. If the compression checks out then have the cooling system pressure tested.

DeftwillP · May 7, 2009

The pictures provided in Joe's link are the exact same pics and descriptions as whats in the back of the Haynes manual.

joe_peters · May 7, 2009

88 Wagonman said:
Those charts are for 2-stroke engines and are only somewhat applicable.

My vote is coolant. As stated above, check the compression. If the compression checks out then have the cooling system pressure tested.

Ash fouled is ash fouled. As it is only one plug of six, my vote is valve stem seal or guide, or possible oil ring.

If the problem was oil type, viscosity, fuel additive, etc. I would expect to see more plugs showing similar condition.

ugly spark plug

DeftwillP

NAXJA Forum User

wycowboy

NAXJA Forum User

Cody90XJ

NAXJA Forum User

DeftwillP

NAXJA Forum User

Saudade

NAXJA Member

Cody90XJ

NAXJA Forum User

DeftwillP

NAXJA Forum User

stewie

NAXJA Forum User

DeftwillP

NAXJA Forum User

joe_peters

NAXJA Forum User

88 Wagonman

NAXJA Forum User

DeftwillP

NAXJA Forum User

joe_peters

NAXJA Forum User

Similar threads