cliffyk

"Gentle" is not a unit of measure, get a torque wrench.

A 20 to 200 lbin 1/4" drive is preferable as then the 156 lbin (=13 lbft, the top end of the spec, that's what I head for) used to torque the plugs is well into the upper half of the wrench's range. This is where it will be most accurate.

HF has a nice one that is sometimes on sale; in fact is is now.

While you're there pick up one of these.



The added length keeps the socket from canting on the plug, I got mine 4 or 5 years ago, one of the best $5 purchases I've made; it's on sale now for $4.

Also pick up a 1/4" female to 3/8" male adapter--you'll likely need it to mate the wrench to your plug socket.

If you don't have, or care to get, a torque wrench then snug hand tight, then and additional 1/16th turn is what to head for. A 16th of a turn is not much, only 22.5°, spend the $20 for the wrench.

In your proposed scenario, replacing the Helicoil would likely not be possible; however inserting a Timsert might be, as they use a larger initial bore then the Helicoil.

devongarver

Nice. I'll be purchasing those two items it looks like. Thanks for the help!

cliffyk

Use the torque wrench on a sturdy bolt a few times to get a feel for it--as the maximum torque rating falls the "click" on click-type wrenches becomes more subtle, on a 1/4" drive wrench it's easy to miss it until you realise what to listen/feel for--after that it becomes second nature...

nickmckinney

Helicoil is the easiest for someone like me to go behind and replace with a Timesert when the head is off the car. Only problem with any of the repairs is getting the depth correct as from what I see showing up at the shop correct depth is achieved about 5% of the time.

cliffyk

Also, while this seems to be an exclusively Ford issue, Google spark plug blow out -ford -mustang and you'll see we have company.

It is fairly common on the '98 through '03 model Miatas, for the same reason. The plugs were only expected to be replaced 2 or 3 times in the engine's life, every 100k miles, so the partially threaded plug holes were used to prevent the plugs from seizing into the head.

I realise I'm sounding like a broken record, but they have to be properly torqued or at least seated by hand and then given another 1/16th turn...

schmallz

Timeserts FTW, just had one installed last week.

Frostbitten

i wouldnt use a helicoil on my engine. Ive seen before where some old helicoils will get brittle and break after changing the plugs a few times. Pieces of helicoil end up falling into the cylinder...

cliffyk

As have I, the larger diameter Helicoils cannot handle any sort of impact loading-if repeatedly subject to pounding loads the spring wire will work harden and break up. That's why I suggested that one plan on selling the car in 15k to 20k miles if Helicoils are used to repair a blown plug.

Lord Ashram

*sigh*

This all makes me a bit depressed... although thanks for the info.

One good thing; I only put about a thousand miles a year on the car, MAX, so hopefully that will help.

Can I ask; does the fact that the car is blown/makes more than stock horsepower have any impact on the repair? I would assume so, but...

Anyway, thanks all... I wish I had the money to fix it correctly, but I just don't (especially since I now have to replace the clutch and front brake rotors on my daily driver... grrr, two breakdowns in 10 hours.)

Thanks!

schmallz

Removal of all the extra super charger components might be a factor, depending on what super charger you run and what cylinder bank is the one missing a plug.

I removed my CAI and T/B before I had it towed to JBA, saved them 15-30 minutes and saved myself 25-45 bucks.