So when a COP fails due to moisture (water in the plug hole) is it shot for good or did it just start missing and throw a CEL because of arcing?

I've repalced 4 of these things in 135,000 miles and this was the first that had water in the hole, not much, only up to the top of the "nut" on the spark plug, 1/8" or less. I just replaced it and I am wondering should I have tried just drying it out?

 

I would have.

Next time, spray it with ether, put it back on, and QUIT WASHING YOUR ENGINE!!!!!!!!!!!!!

 

Yeah right... I don't even wash the outside

I am still trying to figure out how that water got there? We had a lot of rain last week but I didn't run through any puddles that splashed up or anything. It was #5 so maybe the fan blew some water up there? I am baffled.

I am kind of mad I didn't give it a try, but this is the 4th one to fail and I am just used to replacing them.

 

Has to be coolant, if not from a water hose or a pond.

 

I got a 72 Bronco for playin' and it wasn't coolant cuz it was clear, I'm tellin' you it is a strange ordeal...

 

I had two of these (same one rearmost on passenger side) replaced by 76k on my 99 5.4l. The second time the mechanic, not the dealer (who replaced it the first time) said there was a design flaw. The heater hose above it was leaking where it goes into the firewall. The mechanic installed something above the coil to divert any leaking away from the coil. Have had no problem since and I am at 141k.

 

Yeah that was the first one that went out on mine too, I used some foam pipe insulation to divert any moisture away from it, but all 4 C.O.P.'s that I have replaced have been different cylinders and no I don't wash my engine...