Damaged 8mm bolt hole... Best repair?
 

I had a bolt break off in my aluminum engine block. I've been able to get
the broken piece out of the block, but the threads were damaged. Now I need
to repair this...

The original bolt was an M8x1.25x100mm of #8 hardness. If I put a new bolt
into the hole, it does grab but is VERY loose and not suitable to hold it's
braket in place.

I was hoping to find an M9x1.25x100mm bolt, but no luck. I then tried to
locate an 11/32"x4" bolt and again, no luck.

So now I figure I can drill this hole out a bit and cut threads for a
3/8"x4" bolt...

Does this sound reasonable?

My biggest issue is clearance. I had to use a 90' drill to get the broken
bolt out. There is almost no visibility to see if the hole is straight. The
bracket that mounts here does not have any critical tolerances.

Suggestions?

Damaged 8mm bolt hole... Best repair?
 

Noozer wrote:
I had a bolt break off in my aluminum engine block. I've been able to
get the broken piece out of the block, but the threads were damaged.
Now I need to repair this...

The original bolt was an M8x1.25x100mm of #8 hardness. If I put a new
bolt into the hole, it does grab but is VERY loose and not suitable
to hold it's braket in place.

I was hoping to find an M9x1.25x100mm bolt, but no luck. I then tried
to locate an 11/32"x4" bolt and again, no luck.

So now I figure I can drill this hole out a bit and cut threads for a
3/8"x4" bolt...

Does this sound reasonable?

My biggest issue is clearance. I had to use a 90' drill to get the
broken bolt out. There is almost no visibility to see if the hole is
straight. The bracket that mounts here does not have any critical
tolerances.
Suggestions?

http://contractorstools.com/helicoil1.html

--
Joseph Meehan

Dia duit

Damaged 8mm bolt hole... Best repair?
 

Noozer,

Your plan or Mr Meehan's helicoil will both work. My objection to your
plan is your intent to introduce an SAE bolt into a metric engine. The next
person to work on the engine will be using metric tools on this bolt.
With the poor location the helicoil may be the better bet.

Dave M.

Damaged 8mm bolt hole... Best repair?
 

Noozer wrote:
I had a bolt break off in my aluminum engine block. I've been able to get
the broken piece out of the block, but the threads were damaged. Now I need
to repair this...

The original bolt was an M8x1.25x100mm of #8 hardness. If I put a new bolt
into the hole, it does grab but is VERY loose and not suitable to hold it's
braket in place.

I was hoping to find an M9x1.25x100mm bolt, but no luck. I then tried to
locate an 11/32"x4" bolt and again, no luck.

So now I figure I can drill this hole out a bit and cut threads for a
3/8"x4" bolt...

Does this sound reasonable?

My biggest issue is clearance. I had to use a 90' drill to get the broken
bolt out. There is almost no visibility to see if the hole is straight. The
bracket that mounts here does not have any critical tolerances.

Suggestions?



If it's that hard to access you might have a heck of a time trying to
properly install a helicoil insert.

If the bracket is not something you anticipate having to remove and
replace often I'd give a try to using JB Weld to "glue" your new M8x1.25
bolt into that buggered up hole.

Use a Q-tip and solvent to clean out the hole and the new bolt threads
as best as you can, then slap on some JB weld and drive the bolt in as
tight as you dare to without stripping the hole.

That's worked for me and it might for you too, and if it doesn't, you
can start from scratch again.

HTH,

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

Damaged 8mm bolt hole... Best repair?
 

"Jeff Wisnia" wrote in message
et...
Noozer wrote:
I had a bolt break off in my aluminum engine block. I've been able to get
the broken piece out of the block, but the threads were damaged. Now I
need to repair this...

The original bolt was an M8x1.25x100mm of #8 hardness. If I put a new
bolt into the hole, it does grab but is VERY loose and not suitable to
hold it's braket in place.

I was hoping to find an M9x1.25x100mm bolt, but no luck. I then tried to
locate an 11/32"x4" bolt and again, no luck.

So now I figure I can drill this hole out a bit and cut threads for a
3/8"x4" bolt...

Does this sound reasonable?

My biggest issue is clearance. I had to use a 90' drill to get the broken
bolt out. There is almost no visibility to see if the hole is straight.
The bracket that mounts here does not have any critical tolerances.

Suggestions?

If it's that hard to access you might have a heck of a time trying to
properly install a helicoil insert.

If the bracket is not something you anticipate having to remove and
replace often I'd give a try to using JB Weld to "glue" your new M8x1.25
bolt into that buggered up hole.

Use a Q-tip and solvent to clean out the hole and the new bolt threads as
best as you can, then slap on some JB weld and drive the bolt in as tight
as you dare to without stripping the hole.

That's worked for me and it might for you too, and if it doesn't, you can
start from scratch again.

HTH,

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."
I often use Jeff's idea but use a separate stud and nut. After a good
cleaning, smear the hole and stud with JB Weld or similar epoxy and screw
the stud in until it bottoms out. Let it set up for 24 hours, install
washers as desired, install nut and tighten. It makes a stronger and
removeable connection.

Don Young

Damaged 8mm bolt hole... Best repair?
 

On Fri, 30 Jun 2006 19:10:47 -0400, Jeff Wisnia
wrote:

If the bracket is not something you anticipate having to remove and
replace often I'd give a try to using JB Weld to "glue" your new M8x1.25
bolt into that buggered up hole.

LOL!

Why not just arc weld the damn thing, and be done with it? g


--
-john
wide-open at throttle dot info

Damaged 8mm bolt hole... Best repair?
 

"~^Johnny^~" wrote in message
...
On Fri, 30 Jun 2006 19:10:47 -0400, Jeff Wisnia
wrote:

If the bracket is not something you anticipate having to remove and
replace often I'd give a try to using JB Weld to "glue" your new M8x1.25
bolt into that buggered up hole.

LOL!

Why not just arc weld the damn thing, and be done with it? g

It's an aluminum block. Don't think it would weld too well...

I ended up drilling it out for a 3/8-16 bolt and it worked out great

Damaged 8mm bolt hole... Best repair?
 

Noozer wrote:


"~^Johnny^~" wrote in message
...
On Fri, 30 Jun 2006 19:10:47 -0400, Jeff Wisnia
wrote:

If the bracket is not something you anticipate having to remove and
replace often I'd give a try to using JB Weld to "glue" your new M8x1.25
bolt into that buggered up hole.

LOL!

Why not just arc weld the damn thing, and be done with it? g

It's an aluminum block. Don't think it would weld too well...

I ended up drilling it out for a 3/8-16 bolt and it worked out great

If drilling and tapping was an option then the right fix would have been to
put in a Helicoil.

--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)