In the picture below I have all 6 of my spark plugs taken out and removed, I have no idea how long they've been in my engine but they look pretty good. I myself has driven on them for 6000 miles. I have a 2000 Jeep Cherokee I6 4.0. I have suspicion of a cracked head because of coolant loss and a couple other things. What do you guys think?

Are my cylinders burning well? Too lean, too rich, just right?
Any signs of coolant or other contaminates?

Thanks

Left: Cylinder 6, Right: Cylinder 1

 

 

I give them a 7 for originality and a 2 for the swimsuit competition.

They look good to me.

 

Wrong brand. Supposed to be NGKs in a 2000..........

 

^^ Indeed. Go back in with NGK ZFR5N plugs. Gap .035".

The emissions placard on the firewall says (Champion) RC12ECC plugs and they do look like they are woprking okay, but the ZFR5N plugs are more suited to your waste spark ignition system.

 

Would that be a big issue? Brand names? They fit and they're gaped to .035

 

"the ZFR5N plugs are more suited to your waste spark ignition system."

 

Would it be worth the $35 for new ones? Would I notice any performance differences?

 

How long have those Champions been in there so far?

 

People tend to insist on splitting hairs with XJ spark plugs. While the Champions do seem to be better for earlier XJ and NGK better in 00/01, this is some serious hair-splitting. If the Champs were fine, keep going; when it comes time to replace them, give the NGK's a try.

The stock plug preachers will probably have a fit hearing that I have iridium Autolite plugs gapped to 0.050" but the rest of my ignition system is suped-up, too; these plugs would be terrible in a stock XJ.

 

My thoughts exactly. That's why I asked about the age/miles of the Chumpions.

 

Those plugs look perfect to me. Normal wear, nothing more.

 

Yeah, if they're not too old, I'd clean them a little, regap them and continue on with life. They look fine.

 

I have no idea of the actual lifetime of these plugs but I've been driving on them for 6000 miles without any issues such as misfires, ect.

 

+1 on keeping the same ones, they seem fine - even for just 6000 miles, let alone any additional miles lol.