Stripped head bolts. Strongest repair?

[mosman]

So I was using a cheapo torque wrench to do up the head bolts, it failed to click at the right torque as it was seized  One of the head bolts is stripped right out and I need to repair.

Can I tap and use the next size up bolt? or do I need to helicoil? Whats the strongest way?

Thank you!!

[William1]

Have a time-sert installed. Stronger than a helicoil, though a properly installed helicoil would probably be fine too.

[Still Bill]

Can you be more specific?  Is the bolt stripped, or the hole in the block?  Or, is it a stud (stripped on top where nut goes, or in block)?

[BOAB]

4 hours ago, mosman said:

So I was using a cheapo torque wrench to do up the head bolts, it failed to click at the right torque as it was seized  One of the head bolts is stripped right out and I need to repair.

Can I tap and use the next size up bolt? or do I need to helicoil? Whats the strongest way?

Thank you!!

What was seized?  The torque wrench?  The bolt?

[GoneDirtBikeN]

I would not use a different size bolt than the rest. I suspect, although I don't know for certain, is that a different/larger bolt torqued to the same spec will resort in a different force on the cyl/head; obviously you want even tightness on all the cyl/head bolts.

Two approaches would be: 1) have someone, an experienced welder, add material back in and re-tap, 2) threaded insert as you are asking about. A heli-coil done correctly will be just fine. I'd start there as the least expensive repair and you can always go back to option 1.

I always set my torque wrench to a very light setting so that it will "click" easily and then tighten in several stages. I have a good one that stays at home and a cheap one I keep it the toolbox that goes to the track. I constantly check the cheap one against the good one out of paranoia. A couple years later the cheap one is still just fine.

[mosman]

9 hours ago, cjjeepercreeper said:

What was seized?  The torque wrench?  The bolt?

The torque wrench didn't click at the right torque, I then tried it on a car wheel nut and it was seized/broken  So its pull the thread out the head.

 

With the bolts, do you need to replace? They look like stretch bolts or something? With screw like lines running down them if that makes sense?!

[Smoking 2's]

Helicoil is fine, I used them on sparkplugs and they hold up well as you can imagine the constant force being put on a spark plug. I've even seen people fill the hole with JB weld and redrilled and tap, held like new!