Help...spark plug shot out and dont go back in

[Smiles678]

okay one of my plugs shot out of the head about a month after i changed the plugs my self. when the plug came out it stripped the threads so a new plug dont go back in the hole. I went and got a heli coil, its supposed to go around the threads of the new plug and you just screw the new plug in and the heli coil cuts new threads something like a tap and die kit, but the heli coil isnt making the new threads when i screw the new plug in. So my questions are what do i do and what would make the plug come out a month later , to high compression ratio??

[Blaze86Vic]

Over tightening the the spark plug would cause it to strip.

The head has to be removed for this to be fixed, you will never get all the metal shavings out of the combustion chamber. You have to first drill the hole to the size specified by the heli coil. Then you run a tap for the outside threads of the heli coil, locktite that in, and then you have threads. At least that's my experience.

[Freshmeat]

You didn't have to remove the head before you tried to helicoil it, but since you did, I'm not sure... This is a very common thing among the 4.6 motors. What you need to do is find a reputable Ford mechanic in your area and pay him to repair it. It's gonna be somewhere in the range of $300-600 most likely. There's a special tool designed for just this situation. Call around. If they don't know what you're talking about, hang up. You'll find someone who knows Ford enough to get it done right.

[turbo2256b]

Ford uses some special insert. I think its because the water jacket is too close to the plug hole to use helicoils. May not be so on all the 4.6 heads may depend on the year. Regaurddless the head has to come off to repair.

[Freshmeat]

Several people down here had it repaired without removing the head and they haven't had any further issues.

[Grandmarchris]

You can go two ways with this

1.) Spend $600 dollars and fix the head you got

or

2.) Go junkyard hunting or ebaying to find a replacement head...If you have a pre 01 Panther just swap the heads to a 01' + set..Its a quick 30 hp and its cheaper than fixing the heads youve got

[Lincolnmania]

i've fixed a few modular motors with the head on the car......those metal shavings blow out when you start the engine......need the special tool that cuts threads and installs the insert......freshmeat is correct

[seneeb]

can be done with heads in the car (Hell, done em on Navigators with the heads in the truck that's a pita)

as to what causes it? shity head design. three threads hold in the spark plugs on the vehicles that have issues with them blowing out. happens on expiditions and navigators all the time (5.4 mostly, but all the modulars are similar in design)

I'd say go find a junked mark8 and swap the drivetrain!

[P72Ford]

300-600 to fix the head? FRPP sells the PI heads for 400 a side MSRP. You can get them for less from Summit Racing, Jegs, etc.

FRPP p/n's:
Left Side M-6050-P46
Right Side M-6049-P46

The heads come assembled with the production Mustang GT valvetrain and cam. You also need the intake, and a few other bits, but Ford lists it as a replacement part.

Before I'd spend so much money to get a spark plug hole fixed, I'd swap out the heads and gain some more performance at the same time. Probably need a tune, etc as well.

[Smiles678]

Okay i fixed the problem. I had to go to autozone and get the tool ta make the new threads but the scocket that fit on top of the tool was to big to go down the hole where the plug goes so i had to grind it down so the spark plug scocket would fit on it and went to work. I put RTV on the out side of the heli coil so it would stay down there and put the plug in. Let it sit so the RTV could cure and removed the plug just to make sure i could still change the plug if i had to, the car runs fine though i havent pushed it to the limit and i might not for a while

[Freshmeat]

300-600 to fix the head? FRPP sells the PI heads for 400 a side MSRP. You can get them for less from Summit Racing, Jegs, etc.

FRPP p/n's:
Left Side M-6050-P46
Right Side M-6049-P46

The heads come assembled with the production Mustang GT valvetrain and cam. You also need the intake, and a few other bits, but Ford lists it as a replacement part.

Before I'd spend so much money to get a spark plug hole fixed, I'd swap out the heads and gain some more performance at the same time. Probably need a tune, etc as well.

That is ONE way to look at it, but not a good one. Once you order those heads and pay shipping, taxes, etc. you'll be easily over $500. The intake manifold will be another $225. The gaskets to do all the swapping will be somewhere in the $100 range. Then you'll most likely need to swap throttle body, MAF, maybe ECM, etc. You'd be a cool grand in the hole over a freaking spark plug.

Smiles, glad you got it fixed. Let us know if something goes wrong with it.

[1987LTDmasta]

done them on the car without issues. crank the car with no fuel and the plug out, most of the shavings will blow out.

[rf overlord]

Smiles, if your repair doesn't hold, this is what is recommended by Ford modular motor repair experts:

Timesert