Spark plug tread srtipped

I have a 99 navigator and one of the spark plug treads are stripped and when i first start the truk it runs fine and when i ride for a while it runs ruff and losses power. Is there a way to fix this in alumin engine heads?

Believe it or not, you are not the first person to suffer this fate >LOL<

Head to a good local parts store (I would recommend something the pros frequent and not AutoZone or PepBoys, and tell them of your woes. They will sell you a Helicoil kit to repair it…I did this long ago, when I was 18 by just following the directions in my Reader’s Digest Fixit Yourself manual, so it isn’t that tough…Here’s a weblink, that other than having fewer pix, sounds a lot like the manual I followed…

the Heli coils work VERY well. However… you must be at the correct angle (square and straight in reference to the spark plug hole) to make an accurate reem and re thread of the new threads to screw in the thread insert.

Since it is probably because you were changing sparkplugs on the rear, hardest to get at plugs is why it got stripped in the first place. So the repair may not be as easy as thread, insert, and put a new spark plug in. You CAN just “go at it”, and hope for the best, but you only have ONE shot with the Heli coil system (so its got to be done right)

I was at a local parts store the other day, and noticed that now in the Help! section (you know, the rack that has those commonly broken parts, like door handles, window switches, etc.), they have a spark plug helicoil kit for Ford mod motors.

I have seen a lot of comments indicating that “Big Serts” or “Time Serts” are a much more robust repair mechanism than common Helicoil-type inserts. I think that you should look into those. Helicoil is O.K. for something that will never be removed again, but the others are better for plugs and other things that may need to be removed again.

Yeah, some others are better than helicoil but I think a properly done helicoil job will be better than the original aluminum threads. In any case when you drill out or however you enlarge the existing hole to accept the helicoil tap you gotta have a really steady hand. If it’s in an impossible place you may’nt have enough room period to use even an angle drill. By the way, where do you get the non helicoil inserts? I never run across them. Jsph, let us know what happens.

They are both made by TIME-SERT. They have a limited distributor list. Time Serts are reputed to lock into the holes more positively than Helicoil. The Big Serts, IIRC, are made to go into oversize holes that have been previously repaired by more common methods and failed again.