Today I got a P0305 code (flashing) and the truck was running really rough. I took the plug wire boot out of the #5 hole and found coolant all over it. The coolant evidently was deep enough to short out the electrode at the top of the plug. It looks, from What I can see down there with a flashlight, as though the coolant had been in there a while and has stained the walls of the hole. I dried it all out with an air gun, removed the plug and saw nothing wrong with it. I made sure the cylinder had no coolant in it, reinstalled the plug and the wire with die-electric grease and started the truck. Ran smooth. The question is, where did the coolant come from? I'm thinking it can only come from above the plug's threads, which means from the intake manifold gasket? I have not noted any significant loss of coolant. This is something I know has got to be fixed. If it's an intake gasket, I up to doing it. Any suggestions as to what else may cause this would be appreciated.
Thanks

 

It could be a leak from the radiator hose. Sometimes tmey will leak under pressure. Have you had the hose off lately?

 

Yep, the top hose is right there, - so is the manifold water jacket. If it's not leaking right now, - I wouldn't do anything but clean the distribution tank cap.

The system may be overpressurizing, -intermittently. If the vent cap isn't venting properly, pressure will look for another way out.

 

There are no other indications that the coolant came from outside the spark plug hole that I can see. hoses are less than 2 years old (less than 40K miles). I might start it up and let it reach operating temperature, remove the plug wire again and see if I see any wetness in there again.

 

Who said there was? There doesn't have to be, if it's intermittent, there doesn't have to be traces. Traces evaporated.

But,like I said, could be the gasket,- the water jacket isn't a hose lol.

Cleaning the cap vent only takes 5 minutes. Why chance it happening again ?

Hoses could have been installed yesterday, -doesn't matter if the vents plugged.

Watching it will most likley do nothing because same or like pressure conditions have to be met, therefore making it intermittent

Air in the system WILL cause engine hot spots, -again - check cap and burp