Broken Head Bolt

CODI

Member
Okay. So I was finishing torquing down my head bolts yesterday and bolt 17 snapped. I didn't have a bit of trouble with the others, just that one. Yesterday, I was so aggitated that I had to walk away from it. But now I am wondering if I should attempt to use an easy out to remove the broken bolt or if I should just bite the bullet and drill it out and re-tap the hole in the block.

Any suggestion?

Also, does anyone know the what size and grade bolts the 8n uses on the heads? It is a 51 8N, side mount.
 
Codi........eazy outs arn't......some times bolts are just BAD and snap. Yer 8N's headbolts are 7/16-coarse. Always use COARSE into castiron engine block. Torque 40-ft/lbs. Ford used what today would be grade-4. You can use grade 5 or 8. Mox-nix. Unless you bottomed the bolt, you should be able to gently tap it out with sharp center punch. But that probably means yer gonna haffta remove cylinder head to gitt access to yer busted bolt shank. Really desperate shade tree mechanics have been known to arc-weld a washer to the bolt shank and find they kenn turner loose with pliers. ........HTH, unlucky Dell
 
Think of this as a learning experience.

Three lessons here.

First, never ever re-use headbolts that have an unknown history. Simply put, if you did not install them new, then buy new ones. The OEM bolt was 7/16-14 x 2 3/8 grade 8. Good luck finding that size bolt in 2 3/8". So, replace the OEM bolts with 7/16" -14x2&1/2" yellow zinc finish SAE j429 grade 8 Hex Cap screws Part # 0115163 from Fastenal for $0.89 each. Use flat washers 7/16" yellow zinc finish SAE thru-hardened from Fastenal Part # 1133816 for $0.19 each.

Second lesson.....

Do NOT use an ez-out. Do NOT attempt to drill it out. Do exactly as Dell said. Tap it out w/ a center punch.

Third lesson.....

The block doesn't have blind holes, so make sure all the holes are open. What most folks think are ‘blind holes’ are really holes clogged w/ rust. But it doesn't matter because the results of over-torquing a bottomed out bolt are the same.

Lastly......

Torque the bolts in 3 steps, as per the pic: 20-40-65. Then, after the ehgine has been run to operating temp, let it cool & then re-torque them.
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75 Tips
 
(quoted from post at 17:46:55 09/24/15) Okay. So I was finishing torquing down my head bolts yesterday and bolt 17 snapped. I didn't have a bit of trouble with the others, just that one. Yesterday, I was so aggitated that I had to walk away from it. But now I am wondering if I should attempt to use an easy out to remove the broken bolt or if I should just bite the bullet and drill it out and re-tap the hole in the block.

Any suggestion?

Also, does anyone know the what size and grade bolts the 8n uses on the heads? It is a 51 8N, side mount.

You were installing not removing the bolt which usually means it failed under tension - e.g. old fatigued fastener. Unless it snapped because the threads were galled, crossed, or binding you can remove it with just about anything including an E-Z out.

TOH
 
if you have a good feel with the torque wrench you can feel the bolt actually stretching before it breaks. experienced that myself. just removed bolt and replaced with a new one.
 
(quoted from post at 06:39:43 09/25/15)
(quoted from post at 17:46:55 09/24/15) Okay. So I was finishing torquing down my head bolts yesterday and bolt 17 snapped. I didn't have a bit of trouble with the others, just that one. Yesterday, I was so aggitated that I had to walk away from it. But now I am wondering if I should attempt to use an easy out to remove the broken bolt or if I should just bite the bullet and drill it out and re-tap the hole in the block.

Any suggestion?

Also, does anyone know the what size and grade bolts the 8n uses on the heads? It is a 51 8N, side mount.

You were installing not removing the bolt which usually means it failed under tension - e.g. old fatigued fastener. Unless it snapped because the threads were galled, crossed, or binding you can remove it with just about anything including an E-Z out.

TOH

Whut he said That's real experience talk'N, no reason to write a book about it...
 
I have had good luck taking a dremel style tool with a cut off wheel and cutting a slot in the remaining piece of bolt and the turning it out with a screwdriver, have used a drive type impact driver a time or two. If the wheel looks to big to just cut on the broken bolt work it down to a smaller size on a piece of scrap. Like said, that one should spin out fairly easy if its straight in the threads and the threads were fairly clean.
 

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