Loosening stuck bolts?

[FABombjoy]

Try tapping an M8 thread and using en M8 bolt? Time-Sert time?

There is enough room for this, and the M8 bolt will be stronger.

Should you decide later in life that you don't like having a larger, stronger bolt and saving all that money on a Time-sert kit, the proper drill & counter bore tools for an M7 Time-sert are a bit larger than 8mm.

[FABombjoy]

To add, I think 3 out of 4 of my Y-pipe bolts are 8mm now.

And my "task failed successfully" is that I punctured the water jacket on one of them. It's not what you want to do but it's not a big deal that requires pulling the engine or any fancy repairs.
I tapped it to 8mm, selected a replacement 8mm bolt of suitable depth, coated the bottom threads in teflon tape, and installed it. Passed a pressure check no problem.
That was 18 years ago and it's never leaked a drop.

[DrWin]

There is enough room for this, and the M8 bolt will be stronger.

Should you decide later in life that you don't like having a larger, stronger bolt and saving all that money on a Time-sert kit, the proper drill & counter bore tools for an M7 Time-sert are a bit larger than 8mm.

That is actually a great ay of thinking about it. If there is room for an 8mm bolt, sticking one in there isn't a problem. There was also a hole on my alternator that I had to turn up one size to get the deloreango tensioner bracket on. Nobody died or caught fire by having me do that.

To add, I think 3 out of 4 of my Y-pipe bolts are 8mm now.

And my "task failed successfully" is that I punctured the water jacket on one of them. It's not what you want to do but it's not a big deal that requires pulling the engine or any fancy repairs.
I tapped it to 8mm, selected a replacement 8mm bolt of suitable depth, coated the bottom threads in teflon tape, and installed it. Passed a pressure check no problem.
That was 18 years ago and it's never leaked a drop.

As you can see from the pictures above, I used depth markings on the drill to prevent that from happening. I think I dodged that bullet, but it is very nice to know that it can be easily fixed/ignored.

[DrWin]

Ok, now I am off to bed. I think I'm beginning to see thing... I can see inside the hole that the threads are stripped out. But, I can put an M7 bolt in there and torque it to specs (is the spec correct at 14Nm?) with no issue. If I'm lucky I didn't damage the thread too badly. But what then - can I just leave it as is? Or will it fail under load even though it torques to spec? More sleep is needed...
DSC_0537.jpg

[Bitsyncmaster]

A lot of older engines have bolts going into the water jacket. They just use a sealer on the bolt threads. I use Permatex non hardening sealer in that case.

[dmcman73]

Ok, now I am off to bed. I think I'm beginning to see thing... I can see inside the hole that the threads are stripped out. But, I can put an M7 bolt in there and torque it to specs (is the spec correct at 14Nm?) with no issue. If I'm lucky I didn't damage the thread too badly. But what then - can I just leave it as is? Or will it fail under load even though it torques to spec? More sleep is needed...
DSC_0537.jpg

Drill it out and use a timesert. In the event that the regular Time-sert doesn't work because of the hole, they even make a model called "Bigsert" where the other portion of the timesert is much larger to fix really messed up holes like from previous coil repairs (failed helicoils) or a drill bit wandering. http://www.timesert.com/html/bigsert.html

You don't want to have to get back in there after putting it all back together.