I m replacing spark plugs and fuel injection coils on my 03 f150 4.6L V8. I swapped out 2 plugs and coils with no problems. When I got to the third one the plug and coil came out. as I was threading the new plug into the hole I noticed the plug is just free spinning. I looked down the hole and can see threads or what appears to be an insert, may be a helicoil. I contacted the last owner and found out that spark plugs had blown out of the cylinder heads and that his mechanic had repaired them. Now the helicoil shouldn't have threaded down farther into the spark plug hole and nothing came out with the spark plugs I can't figure out why the plugs are free spinning. Any information would be helpful.

 

Sounds to me like it is stripped again.... most likely the head. Can you get the helicoil out? That said, a Helicoil is NOT the way to go on these. They are a one use fix, IMO. You want to use a Time-Sert or Cal-Van insert. Much, MUCH more reliable.

BTW... I am confused about the terminology you used.... "fuel injection coil". Are you replacing injectors or ignition coils?

 

Don't you know?? It's one of them new-fangled, all-in-one, does-it-all fuel injection coil do-hickeys!!!

(Sorry. Had to.)

Pretty sure he means "ignition coils," but yeah, making sure would be good.
And I'll second White's Time-Sert or Cal-Van insert recommendation. They're the only "permanent" fix for plug blow-out.

..

 

I've seen the reviews for the cal-van inserts and I was hoping to not have to go that route but I might have to. Also I got in touch with the previous owner and he informed me that only on plug blew out and it was on the driver side. So the two that I removed on the passenger side do not have heli coils or inserts in them. so once again I ask what could cause the new plugs to be free spinning?

 

I've seen the reviews for the cal-van inserts and I was hoping to not have to go that route but I might have to. Also I got in touch with the previous owner and he informed me that only on plug blew out and it was on the driver side. So the two that I removed on the passenger side do not have heli coils or inserts in them. so once again I ask what could cause the new plugs to be free spinning?

 

I'll bet that one of your old spark plugs has a thread insert on the end. The inserts go into threaded holes. Sounds like the insert came out with the plug. You can probably just transfer it over to the new plug and thread it in.

 

The plug is free spinning..... not coming out or getting tight. Very common with a helicoil repair. "Transferring" the helicoil to another plug and pretending you've fixed it is not good advice.... at all. That will only make matters worse.

 

Some would argue that the first helicoil was "pretending it was fixed".

Like all mechanical things it's best if you understand the basic principles. If you don't then you should probably just follow instructions very closely or have someone else do it for you.

 

Most likley need a "BIG Sert" fix at this point. Makes sure it's Big Sert or nothing is going to work....too late for the other stuff.

 

Sounds like this is already what happened.