Hmmm, not to add to the confusion, but...

I don't know how much relevance this has to crankshaft pulley bolts, but
 on every table saw or radial-arm saw I've ever used, reverse-threaded
nuts are used to hold the blade on the threaded shaft, because the
clockwise (looking at the shaft) rotation of the blade would cause a nut
with a normal thread to come loose and spin off.  And yes, they do
tighten up, with very little use.

---
avast! Antivirus: Outbound message clean.
Virus Database (VPS): 0544-8, 11/04/2005
Tested on: 11/5/2005 10:36:31 AM
avast! - copyright (c) 1988-2005 ALWIL Software.
http://www.avast.com

As I said before, the il is a crude friction stabilizer. It is common for
high-stress bolt situations to specify friction stabilizers, either as a
coating, or as user-applied materials.

The bolt on your crank pulley is NOT "self tighetening".

Whatever the cause of the face wear (the face isn't oiled, remember), it
isn't moving.

The pics are here:
http://www.tegger.com/hondafaq/misc/jim-beam_pulley_pics/

Unfortunately, the pics aren't really evidence of much other than this:
You've taken photos of a pulley from an unknown car with an unknown history
given unknown servcicing by persons of unknown competence.

These pics are strongly suggestive of a pulley having been installed at
some point with no Woodruff key, or otherwise installed incorrectly. I can
assure you a pulley properly installed will not gall that way.

A properly tightened joint dowes not rotate. Your pictures do not prove
anythng one way or the other because we do not know the car's history.

I agree with Jim that, upon vibration, the cut of the threads does not tend
to tighten the bolt. Your Figure 3, Burt, doesn't show anything different
from a coarse thread cut. The threads are helically cut on both coarse and
fine thread designs, of course, so back-and-forth vibrating forces will tend
to have the same effect on both, absent other forces being at work.

So far I think the rest of the site has much to offer.

I would suggest

1.
Making sure you use the right units for torque. The units for torque in
automobile manuals are conventionally given as ft-lbs or newton-meters in
manuals. I realize English is not your first language, so maybe something
got lost in translation here.

2.
From my reading, "momentum force" is not a commonly accepted way of
characterizing the forces acting on the pulley under normal car operating
conditions. Inertial force is okay, being one way of saying centrifugal
forces are what mostly tend to push it off the crankshaft. (Recognizing, for
the physics-inclined among us, that whether it's accurate to call the
effects of centripetal forces "centrifugal forces" depends on what frame of
reference is used. What "centrifugal force" means in practical, hands-on
applications is well-understood, so I'm using it.)

3.
Your wording is not perfect, but then rarely is mine. I can understand your
other points and tend to agree with them. I think it is particularly
noteworthy that oil is supposed to be used, /not/ something like Loc-Tite,
on the threads. For now, I agree the purpose is to ensure that the bolt and
shaft threads can move relative to each other upon commencing operations.

4.
I want to look further into your hypothesis about what causes that loud
crack when the bolt frees. I think you're right that it may be due to
release of a large axial load in the bolt and so is a sonic boom(?). If it
is a sonic boom, then that does tend to suggest that the pulley bolt is in
fact under very high axial load. It's not, like Tegger has been contending,
merely the galling of female and male threads against each other,
essentially adhering one to the other.

5.
OTOH, I think galling does play a role. One need only consider some of the
exhaust bolts that become so hard to remove. Many of them are fine threaded
(not sure if they're super-fine, non-standard fine threads or not). Fine
threads are used to minimize the likelihood of the bolts vibrating free
during operation. The greater surface area contact between male and female
threads is what holds fine threaded applications more tightly together than
coarse threads. But unlike the pulley bolt, the exhaust bolts don't have a
rotating mass attached to them. The exhaust bolts also get very hot, though,
and they also vibrate while they're hot. Heat cycling--temperatures being
alternately raised and lowered, causing the metal to expand and contract and
fill in whatever microscopic gaps there are between male and female thread
surfaces--may play a huge role, as I believe SoCalMike, for one, proposed.
So the exhaust bolts seize up principally due to galling. (Not sure they're
all so terribly exposed to, say, gases of combustion causing corrosion,
though. Temperature may cause foreign materials on the bolt to crud up the
thread surfaces, OTOH.) The exhaust bolts are all I believe notably smaller
in diameter than the pulley bolt. Is the torque required to loosen these
exhaust system bolts in some proportion to the pulley bolt torque? I
couldn't say with certainty. In sum, right now I personally can't rule out
either a highly axially loaded bolt or galling due to massive heat cycling
causing that loud "crack" when one frees the pulley bolt.

6.
At the bottom of your site, I do not think your explanation of why the
loosening torque is often higher than the tightening torque is accurate. I
agree with boltscience.com , Tegger, and Scott that the main reason the
loosening torque is higher is the difference between the dynamic coefficient
of friction and the static coefficient of friction. The static coefficient
is higher.

Jim, re your current investigation: All you noted is interesting. For me,
the fretting on the one car's bolt-washer mating surfaces is particularly
so.

I would hypothesize that the 92 vehicle hadn't been in operation long with
the loc-tited bolt. Also, if it had continued to run for some time, it was
at higher risk of the pulley bolt coming undone, since no oil was used to
facilitate relative (tightening) motion between female and male threads,
leaving the vibrations/pulsing of the pulley against the bolt head to
potentially overwhelm the system, vibrate free the bolt, and so knock the
pulley free of the crankshaft.

I hope you bring "pillows" to the yard when you're jumping up and down on
that 1.5 foot breaker bar.   ;-)

I may take pictures in a few weeks if I free up my Civic's pulley bolt
during a tire rotation, and the safety engineers among us can have at it.

This remains an interesting academic debate, for bona fide engine
enthusiasts (pity the poor soul who comes here lately just wanting to know
whether he should change the washer for his oil drain plug at every oil
change!). I trust others here are wise enough to keep the boxing gloves off
and attend to them. I for one put my web site back up, and it does have some
changes reflecting some of the discussion here, FWIW.

Elle
Still an amateur learning much from those with specialized experience!

I still dunno. I've seen galled steel flat washers and bolt heads various
places before (but I don't recall where they have been), so I wouldn't have
thought it was unusual. I would speculate that the torque we need to apply
to break crank bolts loose isn't being directed to the threads but to the
head, where the galled surfaces are responsible for the excessive
break-loose torque. Pure speculation, though.

Usually crank bolts (Honda or otherwise) need to loosen a quarter turn or so
before they come free, and then there is no evidence of the threads
galling - leading me to the speculation of the galled head and washer
surfaces being the key. That would also be consistent with the observation
that the break-loose torque goes up over the years, if engine heat and/or
vibration is important in the development of the galling.

I don't think we have enough to work with to come up with a definitive
answer.

Mike