Stripped Head bolt

The last bolt that I took out of my 1972 Tbird head looked like this. The one on the right.  Also the one on the right is cleaned with brake clean.


So how do I fix the threads in the block ?

Looks like I used anti seize on the threads the last time I rebuilt this engine about 20 years ago.

Do i just run a tap into the block to clean up the block threads.  Does this look like the bolt threads gave out.  Or how do I tell if the block threads gave out.  And if it is the block threads how do I fix this?  
do i throw away the block?

An help or suggestions would be greatly appreciated!

Bob
Tucson

Never ran in to a block head bolt being striped I have ran into water pump bolts striped I just ran a tap in the treads and cleaned them up and replaced the bolts but they don't tq down with a 100 plus. I would run a tap down it then take a flashlight and check the treads if the look good put the head back on and tq it down to specs see if it holds. If it does pull the head back off and check the hole if it still looks good I would run it. But make sure the block not cracked or bust around the hole and cause the bolt to strip.

Run a tap in block and check threads.
If they look questionable.
Drill and tap for heli-coils.

From the looks of the bolt on the right, I'd bet that hole is stripped..

I just had to do some on our latest Dirt Late model engine.

Don't use anti seize, just use some oil.

NEVER USE HELI COILS   when and if you have to fix threads in the Block use Thin Certs (or Keencert) they are the same , they install like Helicoils but are made of a solid piece of steel and lock into the block to keep from backing out, not a wire which will back out with the bolts .....Also when using Thin Certs they make 2 sizes you can get a regular or a thin wall.. for tighter spots..

the Coug wrote:NEVER USE HELI COILS   when and if you have to fix threads in the Block use Thin Certs (or Keencert) they are the same , they install like Helicoils but are made of a solid piece of steel and lock into the block to keep from backing out, not a wire which will back out with the bolts .....Also when using Thin Certs they make 2 sizes you can get a regular or a thin wall.. for tighter spots..

QtrWarrior wrote:

the Coug wrote:NEVER USE HELI COILS   when and if you have to fix threads in the Block use Thin Certs (or Keencert) they are the same , they install like Helicoils but are made of a solid piece of steel and lock into the block to keep from backing out, not a wire which will back out with the bolts .....Also when using Thin Certs they make 2 sizes you can get a regular or a thin wall.. for tighter spots..

Mike No offense but I have seen hundreds of Heli coils back out and having to disassemble more of an engine than need be cause of them...

the Coug wrote:

QtrWarrior wrote:

the Coug wrote:NEVER USE HELI COILS   when and if you have to fix threads in the Block use Thin Certs (or Keencert) they are the same , they install like Helicoils but are made of a solid piece of steel and lock into the block to keep from backing out, not a wire which will back out with the bolts .....Also when using Thin Certs they make 2 sizes you can get a regular or a thin wall.. for tighter spots..

Mike No offense but I have seen hundreds of Heli coils back out and having to disassemble more of an engine than need be cause of them...

Coug.. None taken..

The secret is installing them correctly.
That means the right size hole for the tap, etc, etc...

It is NOT something someone should do for head bolts, if they have never installed any before...

noblefix.com

I've never used a Thin Cert or seen one used...not because of any opinion of them, I'm sure they're a great product. I just never saw a need since I've never seen a Heli-Coil failure. My dad used them for decades (he managed a municipal airport and operated a full service FBO.) and I've used them in my garage. The FAA is ok with them in many applications...I am, too, since my car never gets more than a couple feet off the ground.

The link above offers a variety of inserts for specific purposes.

maverick wrote:noblefix.com

I've never used a Thin Cert or seen one used...not because of any opinion of them, I'm sure they're a great product.  I just never saw a need since I've never seen a Heli-Coil failure.  My dad used them for decades (he managed a municipal airport and operated a full service FBO.) and I've used them in my garage.  The FAA is ok with them in many applications...I am, too, since my car never gets more than a couple feet off the ground.

The link above offers a variety of inserts for specific purposes.

Maverick in higher torques the wire seemd to pinch on the bolt threads and try to come back out with the bolts,, I know in most instances a Cheap ole Helicoil will be somewhat ok, But I prefer not to be that somewhat part...and yes I have used them in the past But not any more...I look at it now as Fix it right once and never worry about it again. I hate doing stuff over cuz some cheap part failed or was fixed wrong...

+1

Time-sert threaded inserts work fantastic!
I did a repair on a magnesium case Porsche flat 6 where all factory head stud threads were replaced with Time-Sert inserts.
They are easy to install (one must ensure the drilling and tapping is done correctly)

Cheers!

the Coug wrote:

maverick wrote:noblefix.com

I've never used a Thin Cert or seen one used...not because of any opinion of them, I'm sure they're a great product.  I just never saw a need since I've never seen a Heli-Coil failure.  My dad used them for decades (he managed a municipal airport and operated a full service FBO.) and I've used them in my garage.  The FAA is ok with them in many applications...I am, too, since my car never gets more than a couple feet off the ground.

The link above offers a variety of inserts for specific purposes.

Maverick in higher torques the wire seemd to pinch on the bolt threads and try to come back out with the bolts

The backing out in this case, is because the hole was drilled too small, causing threads in heli-coil to be too small..
Like I said, It has to be done correctly.
I know, I've installed thousands in aircraft parts for a LONg time...

Done, right, there is no reason a heli-coil should back out of the hole... NONE...

dfree383 wrote:Don't use anti seize, just use some oil.

                                                                                                                      You beat me on that post defee. When I saw the antiseize, I wondered if that caused the problem in the first place? The Op might want to check all his head bolt threads closely, and maybe run a Tap down them if they feel tight with a clean known good bolt by hand. Hopefully he will not have to pull the heads off for another 20 years, as all the threads may be weak, as the antiseize increased the torque if he put them to factory spec. If it was not for the antiseize deal, I would say it looks like trash got into the treads.

Looks like it galled to me. Clean threads + oil + proper torque =

I had one that I had too heli coil a few yrs back.Not a really big deal if you use the correct bit and be careful. Still fine as far as I know. The new deal that Coug mentioned is suppose to be better,but,i personally have never used them.

You could possibly use a roll form tap to chase the threads or get an oversize tap also.



Tore