92 f150 with a straight 6

109 000 miles the #3 plug keeps coming loose i was wondering why...every thousand miles or so itll run bogged down, so i go check the plug and it needs retightened . i can turn it by hand. all the other ones are tight any suggestions

 

anyone have ANY ideas?

 

Check the threads on the plug and the head. One or both are probably stripped.

 

bump bump.....anyone else? its a new plug goes in tight just gets loose lil help....it runs bad with the plug loose i wanna know why plug is getting loose in the first place...all the others are tight infact i cant remove the first 2

 

I don't know why, but I've got one that did that occasionally on my 95 300. I bought a spark plug thread tap, and cleaned up all the holes. It doesn't seem to be a problem anymore.

The ultimate fix would be to have the plug hole drilled out for a steel spark plug insert, but you may or may not have to remove the head depending on what kind of kit you can find.

Never had another vehicle do it, but this is one of the last vehicles on the road in any significant numbers that uses the large plug thread pattern -old style spark plugs. Maybe that's got something to do with it?

 

You can chase the threads as already suggested with a spark plug tap or you can buy helicoil save a thread kit (45 bucks). The kit you drill out the head slightly, run the tap they provide thru, then you insert the steel insert and tap it down with the special tool. Ive used it before with great success-it works great.

 

thanks guys