1990 renix 4.0 xj is bubbling around #3 spark plug. I just watched it do it for about atleast 15 min with engine running. Here are pics

 

Have u checked the plug for tightness?

 

Yes all snug tight I just replaced the plugs about 1 month ago. Uses a very little amount of antiseize on the threads when Re installed.

 

I don't remember if the plugs have a washer or not but if they do did you replace it or did the old on stay in the hole. Also it can be as simple as dirt or crud isn't letting it seat correctly.

 

U just checked tightness or a month ago? Threads could be crossed/bad.

 

Its good and tight, new plugs had crush washers installed. Checked tightness today when posted and good and tight

 

Bad threads, or gasket, or a crack, or bad plug.

 

Something run down in there and boil? Does it do it when it's not good and hot?

 

No run down, completely wiped clean and watched the area and continued to do it. I wouldn't think its oil thought because that would be burned off in the combustion process correct?

 

Boy, you got a good one there! Certainly wouldn't expect anything to be coming up past a tightly sealed plug. See what you can wipe with a paper towel and have a look? Put a little soapy water and see if it bubbles? Stick a little piece of rag or something above the washer, and below the edge of the cover and make sure it's coming from below, and not running down? Swap the plug with another? Got me! Does it do it when it's not good and hot?

 

Tomorrow I will check if it always does it or if its only when warm. I will do a little more troubleshooting.