Ignition Coil / Plug question

[Scottb4857]

Went and changed the plugs on 99LC. Have no idea if/when they were ever changed in the 235k life of this hundy. Wasn't having any misfire or codes, just part of new to me tune up.

All the coils/plugs looked good except #2 from the front on the passenger side. As seen from the pic - dirty, caked on grime and dirty on top of plug. Picture cut off, but tip of plug was about the same as all the others.

So is this just a bad grommet on top and dirt/water getting on the coil? Improperly seated plug with oil/combustion coming back out? Or something worse?

Any thoughts from the guys who know this motor better than me? I'm replacing this coil regardless but appreciate the help.

Thanks,
Scot

 

[badlander]

If the spark plug was tight I would suspect a leaking valve cover gasket around the spark plug hole. Not serious. Replace the gasket when you get the time. The coil pack is probably fine. Leave it in until you get the gasket changed to stop the leak then put the new coil pack in and save the old one for a spare. Easy.

 

[chrisbruck]

I changed my original plugs over the holidays and had one of mine look identical. The plug on my offending one was loose though, only finger tight. It ran fine with the loose plug which surprised me.

 

[hankinid]

I changed my original plugs over the holidays and had one of mine look identical. The plug on my offending one was loose though, only finger tight. It ran fine with the loose plug which surprised me.

I've seen loose plugs in cycles look the same...my first thought.

Though if it took a bit of torque to loosen, I'd agree with badlander's diagnosis.

They will run OK with a loose plug or bad coil pack, as there are 7 more cylinders to take up the slack.

For installation, I use a light coating of copper Never-Seez on the plug threads, and a torque wrench. Last year I heli-coiled a thread in neighbor's Sequoia ...he didn't believe using a torque wrench...easy job but R&R-ing the head was not especially fun.

Steve

 

[Scottb4857]

Thanks for the replies gentlemen. Taking the plug out it felt about the same as the rest so I'm also leaning toward badlander's diagnosis.

I'l go around and re-torque all the valve cover bolts while I'm in there as a stop gap till I have time to swap out the gasket (and when it's not 30 degrees and raining outside). And I agree with you Steve, stuff like plugs, valve covers, water pumps, etc.. should always be done with a proper torque wrench. Too easy to overestimate the amount of force you're applying even with a small 1/4" drive socket driver.