Ignition coil bolts snapped and expanded on bottom---any ideas why?

So are you going to replace the valve cover or tried it remove the broken pieces?

 

100% overtorque is enough to tell a story in my book.

 

Yep. They are M6 bolts most likely Toyota 9 grade or industry ISO 8-8. If you tighten them more than 90 degrees after full run down, you are over torquing them; torque wrench or no torque wrench.

You could replace them with a higher grade ISO 10.9 bolt. They can be had as M6x1.0x30 flange bolts.

 

Kinda like that saying, "when all you got is a hammer, everything looks like a nail." But in this case, "when all you got is a high powered torque wrench them bolts spin real fast past their limit..."

 

These are the wee locator bolts holding down the coils. You could snug those one handed with a screw driver style nut driver. Just use common sense with those.

torque value may be in attached, likely in inch pounds, which you divide by 12 to get foot pounds.

you’re not the first to snap these off.

addendum: yeah, 80 inch/pounds, 80/12 foot/pounds, or 6.7 foot/pounds:

 

Wth . Seriously we're talking these bolts aren't you just using a nut driver in your hand You're thwacking these things down so hard You're breaking them off maybe you should be bending lacrosse sticks or something I mean a car work may not be suitable for you maybe something along those lines what would give anyone the inclination to even be doing anything like this just the look of the threaded shaft that you're putting into the metal dictates touch the top of the coil add a 16th of a turn if that and leave it alone but hey common isn't so common I guess these days I don't know.

 

Wee quibble: a torque unit is a length ✕ a force, not a length / a force.

So, you know you're doing the conversion right when you say;

(80)(inch ✕ pound) ✕ (1 foot / 12 inch) (one foot is twelve inches, so that's really only multiplying by 1, doesn't change the real value, only the units) and 'inch' top and bottom cancels, leaving you with 6.7 foot ✕ pound.

 

1/16 turn is not enough. It will be too loose and back out with heating-cooling cycles and vibration. If you happen to be heavy handed, buy a set of shortie combination wrenches. The 10mm wrench is about 4 inches long. It is hard to over torque with that short lever arm

Again, a maximum of 90 degrees after full rundown will not overtorque an M6 bolt.

 

Sounds great mine go in hand tight not trying to kill it If you have to torque a bolt this small we lost the battle oh well.

 

If it was mission critical I would just consult my machinist handbook. This is a non-critical bolt holding down a coil for goodness sakes I mean this is hysterical but yeah good information If you're talking coil hole down bolts on a valve cover yeah.

 

Exactly. There's been at least two reports here, novice wrenchers torqued those little guys to 80 foot/pounds (sorry Chap).

Both those instances the heads came right off.

 

To me, having been trained in the aircraft and aerospace industry, proper tightening of all fasteners is mission critical.

Loose fasteners are as bad as torqued to failure ones.

 

In general, probably not, but it also depends on the length and hardness of the bolt.

In the end, folk with enough experience (ie have a "torque calibrated" arm) can tighten many fasteners "by feel" and be fine.

Those with less experience NEED a torque wrench and specifications. Otherwise they have things strip, snap, or otherwise come apart.

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As others have mentioned, those bolts broke because they were way over torqued. Typical spec for a 6mm bolt is 6-9 ft-lb.

13 ft-lb is fine for a 8mm fastener (grade 8.8) - which has close to twice the cross section vs 6mm.

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The spark plugs aren't 100% oem but theyre a different denso plug that fits well

Curious about this also. DENSO makes a few different iridium plugs for the car. What model did you use and have you been happy with them?

 

Instead of apologizing to me, why not just use one of the accepted, and correct, ways of writing it? You can:

just put the words together: foot pounds

use a multiplication dot if you're feeling fancy: foot·pounds

or a hyphen: foot-pounds (sure, somebody could mistake it for minus, but unit conversions don't work that way, and it's a recognized conventional way of writing the unit).

When you write it as foot/pounds, which would be a correct spelling of some totally different unit, feet per pound, you could measure thinness of wire that way), it isn't very much skin off my nose as I already know better. It's more of a stumbling block for other readers who might not, and who might pick it up from you and repeat it, or even try to do the math with it. Your apology would be better directed at them.

 

I've got a similar quibble: people saying "I could care less"; which begs a few questions, whereas the original expression "I couldn't care less", makes sense. But consider:

When the original expression gets corrupted, but everyone knows what you mean, maybe it's time to let go?