head thread repair on aluminum block

> wrote
> jim beam wrote:
>
>> > Well, do you think it would be possible to find a
>> > 12mmx1.5 bolt to use
>> > in its place? The bolt is 6 3/8 inches and the
>> > threaded part is 1
>> > inch. The head is 14mm. I don't know where to look
>> > for this kind of
>> > thing... the best I could think of is maybe some other
>> > Honda uses a
>> > similar bolt.
>>
>> best stick with the original bolt regardless.
>
> Is it possible that the bolt really was a 1.25

I would bet money the pitch is 1.25. The online factory
service manual for this Accord says in two places it's a
1.25 pitch bolt. Plus, only one piece of evidence you have
(your own measurement of the bolt pitch) suggests it's not
1.25. "Believe your indications." -- Rule from navy nuke
program when analyzing problems with the plant.
(Psychological studies show a basis for resisting believing
one's indications. One has to 'resist the resistance,' blah
blah when making electro-mechanical diagnoses.)

> but was able to thread
> into the 1.5 gauge anyway?

Yup. Plus all that soft metal will rework itself without
much difficulty, but not to the point where I would trust
the holding power of the setup.

Re-helicoil? I have never done a helicoil job, so I ask for
my own edification as much as yours. The net's reports on
the use of helicoil inserts to repair stripped threads
certainly are promising.

I would be checking the other, so far relatively untouched
head bolts to see that they are 1.25 mm pitch. Get yourself
to a True Value hardware or other store that has a bin of
M12x1.25 etc. nuts, and confirm the pitch?

> Of course, maybe their gauge was cross
> threaded by another customer.

> So what can be done about it jumping around? It'd be nice
> to get
> something approximating the correct torque on it.

Isn't "correct torque" rather tangential to the main
concern, namely, how tight the head is held onto the engine?
I personally would not focus on "correct torque" prior to
getting the factory specified male and female threads into
good repair.

Just an amateur here.

That resistance thing is called "denial" in civilian psychology courses, and
it is probably the most powerful force known to humans. You are quite right
that "how tight the head is held onto the engine" depends on the thread
pitch. Finer threads have more leverage, and therefore give you more
tightness for the same torque.

Earle

"Elle" > wrote in message
ink.net...
> > wrote
> > jim beam wrote:
> >
> >> > Well, do you think it would be possible to find a
> >> > 12mmx1.5 bolt to use
> >> > in its place? The bolt is 6 3/8 inches and the
> >> > threaded part is 1
> >> > inch. The head is 14mm. I don't know where to look
> >> > for this kind of
> >> > thing... the best I could think of is maybe some other
> >> > Honda uses a
> >> > similar bolt.
> >>
> >> best stick with the original bolt regardless.
> >
> > Is it possible that the bolt really was a 1.25
>
> I would bet money the pitch is 1.25. The online factory
> service manual for this Accord says in two places it's a
> 1.25 pitch bolt. Plus, only one piece of evidence you have
> (your own measurement of the bolt pitch) suggests it's not
> 1.25. "Believe your indications." -- Rule from navy nuke
> program when analyzing problems with the plant.
> (Psychological studies show a basis for resisting believing
> one's indications. One has to 'resist the resistance,' blah
> blah when making electro-mechanical diagnoses.)
>
> > but was able to thread
> > into the 1.5 gauge anyway?
>
> Yup. Plus all that soft metal will rework itself without
> much difficulty, but not to the point where I would trust
> the holding power of the setup.
>
> Re-helicoil? I have never done a helicoil job, so I ask for
> my own edification as much as yours. The net's reports on
> the use of helicoil inserts to repair stripped threads
> certainly are promising.
>
> I would be checking the other, so far relatively untouched
> head bolts to see that they are 1.25 mm pitch. Get yourself
> to a True Value hardware or other store that has a bin of
> M12x1.25 etc. nuts, and confirm the pitch?
>
> > Of course, maybe their gauge was cross
> > threaded by another customer.
>
> > So what can be done about it jumping around? It'd be nice
> > to get
> > something approximating the correct torque on it.
>
> Isn't "correct torque" rather tangential to the main
> concern, namely, how tight the head is held onto the engine?
> I personally would not focus on "correct torque" prior to
> getting the factory specified male and female threads into
> good repair.
>
> Just an amateur here.
>
>

I suspect there's more going on here, like the OP is working
in an independent or dealer shop (nothing wrong with either,
of course); has given a quote to the customer; so the budget
is a bit tight; and can't a proper helicoil kit run some
serious change? I was googling on the costs of kits and am
not clear on that.

Seems like these poor folks have found themselves in a
morass here. I am interested in the outcome but fear someone
is going to end up paying through the nose. OTOH, next time
I bet this is a piece of cake.

"Earle Horton" > wrote

> That resistance thing is called "denial" in civilian
> psychology courses, and
> it is probably the most powerful force known to humans.

Probably too often discussion of the phenomenon is applied
to "emotions" (e.g. denying that Jane could have messed over
Paul by sleeping with Paul's best friend yada). Fact is the
technically inclined have to remember it applies to cold
hard science, too.

> You are quite right
> that "how tight the head is held onto the engine" depends
> on the thread
> pitch. Finer threads have more leverage, and therefore
> give you more
> tightness for the same torque.
>
> Earle
>
> "Elle" > wrote
>> > wrote
>> > jim beam wrote:
>> >
>> >> > Well, do you think it would be possible to find a
>> >> > 12mmx1.5 bolt to use
>> >> > in its place? The bolt is 6 3/8 inches and the
>> >> > threaded part is 1
>> >> > inch. The head is 14mm. I don't know where to look
>> >> > for this kind of
>> >> > thing... the best I could think of is maybe some
>> >> > other
>> >> > Honda uses a
>> >> > similar bolt.
>> >>
>> >> best stick with the original bolt regardless.
>> >
>> > Is it possible that the bolt really was a 1.25
>>
>> I would bet money the pitch is 1.25. The online factory
>> service manual for this Accord says in two places it's a
>> 1.25 pitch bolt. Plus, only one piece of evidence you
>> have
>> (your own measurement of the bolt pitch) suggests it's
>> not
>> 1.25. "Believe your indications." -- Rule from navy nuke
>> program when analyzing problems with the plant.
>> (Psychological studies show a basis for resisting
>> believing
>> one's indications. One has to 'resist the resistance,'
>> blah
>> blah when making electro-mechanical diagnoses.)
>>
>> > but was able to thread
>> > into the 1.5 gauge anyway?
>>
>> Yup. Plus all that soft metal will rework itself without
>> much difficulty, but not to the point where I would trust
>> the holding power of the setup.
>>
>> Re-helicoil? I have never done a helicoil job, so I ask
>> for
>> my own edification as much as yours. The net's reports on
>> the use of helicoil inserts to repair stripped threads
>> certainly are promising.
>>
>> I would be checking the other, so far relatively
>> untouched
>> head bolts to see that they are 1.25 mm pitch. Get
>> yourself
>> to a True Value hardware or other store that has a bin of
>> M12x1.25 etc. nuts, and confirm the pitch?
>>
>> > Of course, maybe their gauge was cross
>> > threaded by another customer.
>>
>> > So what can be done about it jumping around? It'd be
>> > nice
>> > to get
>> > something approximating the correct torque on it.
>>
>> Isn't "correct torque" rather tangential to the main
>> concern, namely, how tight the head is held onto the
>> engine?
>> I personally would not focus on "correct torque" prior to
>> getting the factory specified male and female threads
>> into
>> good repair.
>>
>> Just an amateur here.
>>
>>
>
>

There is a product out there that is used on Nuclear subs, and industrial
equipment that will fix this problem if you can get to it. I've used it,
sold it, and gave it to others. One time I fixed a Cummins diesel head crack
with it, and it's still running.....

I'ts expensive, and I haven't seen any around in awhile. Google for Belzona
products. It's possible someone will give you the little that you need.

MM^^

Elle wrote:
> I suspect there's more going on here, like the OP is working
> in an independent or dealer shop (nothing wrong with either,
> of course); has given a quote to the customer; so the budget
> is a bit tight; and can't a proper helicoil kit run some
> serious change? I was googling on the costs of kits and am
> not clear on that.

Nope, just a backyard job that fell apart midstream (and had several
cooks in the kitchen who I'm collectively speaking for). The helicoil
kit cost $60 from Amazon.

> Seems like these poor folks have found themselves in a
> morass here. I am interested in the outcome but fear someone
> is going to end up paying through the nose.

In the end, the worst case is drop in a used motor.

> OTOH, next time I bet this is a piece of cake.

I hope there won't be a next time <G>

Elle wrote:
> Re-helicoil? I have never done a helicoil job, so I ask for
> my own edification as much as yours. The net's reports on
> the use of helicoil inserts to repair stripped threads
> certainly are promising.

Yeah, it's more a problem that the damage is already done and now what?

> Isn't "correct torque" rather tangential to the main
> concern, namely, how tight the head is held onto the engine?

Yes.

> I personally would not focus on "correct torque" prior to
> getting the factory specified male and female threads into
> good repair.

If anyone has any suggestions on how to do that, I'm all ears.

Earle Horton wrote:
> That resistance thing is called "denial" in civilian psychology courses, and
> it is probably the most powerful force known to humans. You are quite right
> that "how tight the head is held onto the engine" depends on the thread
> pitch. Finer threads have more leverage, and therefore give you more
> tightness for the same torque.

That makes no sense. If anything finer threads would lose more of the
torque value to friction, the same friction that prevents a finer
thread bolt from backing out under the same vibration that would back
out a coarse thread bolt. So in the end you need a higher torque value
to deliver the same clamping force.

On 4 Oct 2006 12:35:53 -0700, wrote:

>
>Earle Horton wrote:
>> That resistance thing is called "denial" in civilian psychology courses, and
>> it is probably the most powerful force known to humans. You are quite right
>> that "how tight the head is held onto the engine" depends on the thread
>> pitch. Finer threads have more leverage, and therefore give you more
>> tightness for the same torque.
>
>That makes no sense. If anything finer threads would lose more of the
>torque value to friction, the same friction that prevents a finer
>thread bolt from backing out under the same vibration that would back
>out a coarse thread bolt. So in the end you need a higher torque value
>to deliver the same clamping force.

Not so.
It is called Mechanical Advantage.

With fine thread, you need 20 turns of wrench to say sink fastener 2
inches.

With coarse thread, maybe 10 turns of wrench to sink fastener 2
inches.

So you have a virtual 2 to 1 gear ratio with a fine thread in this
example, and a 1:1 gear ratio with the coarse thread.

Use your head. If you put the same torque on the fine thread that you
put on the coarse thread, you will get TWO times the clamping force,
friction losses notwithstanding.

A mind is a terrible thing to waste.

Lg

> wrote
> Nope, just a backyard job that fell apart midstream (and
> had several
> cooks in the kitchen who I'm collectively speaking for).
> The helicoil
> kit cost $60 from Amazon.

Great on all points. (I mean, better than having a customer
breathing down your neck!) If you are feeling wealthy
enough, I hope you'll confirm the 1.25 pitch size, buy
another kit (Ebay?), and see how that works. Er, maybe wait
until others who have done helicoil jobs chime in on how
successful a "re-do" is first, though.

Thanks for the update. I am sure someone down the line is
going to learn from this. There really aren't too many
reports of helicoil jobs on head bolt threads for the Honda
newsgroups.

wrote:

> Nope, just a backyard job that fell apart midstream (and had several
> cooks in the kitchen who I'm collectively speaking for). The helicoil
> kit cost $60 from Amazon.

I'm getting back to this thread late, but want to agree with the people
who proposed that your head bolts are actually 12mm X 1.25mm pitch.
You'll be hard pressed to find a 12mm X 1.5mm bolt on any (real) Honda
product. That excludes the Passport, etc.

At this point I think the engine is probably beyond saving, unless
there is a double-oversized helicoil product out there I'm not aware
of. It's too late now, but the answer to your "what size Helicoil tap"
question is -- 2mm larger than the intended bolt size in the same
pitch. i.e. repairing a 12mm X 1.25mm hole would require a 14mm X
1.25mm tap (and appropriate drill size). The Helicoil taps don't have
their actual measurments listed on them, but I have measured and
matched all of the common sized metric Helicoil taps to regular tool
taps. Furthermore I have used standard taps in place of the Helicoil
tool with total success.

Toyota MDT in MO