[Vwdiesel] What is the candle wax GP extraction trick ? (fwd)

[Val Christian]

What Cassie describes is very good, and where you're at if you're
faced with sticky glowplugs.  Al cylinder heads tend to strip when they're
warm.  Been there.  Work the temperature for YOU, so that you're comfortable
and can FEEL things.  It was in 78, but my recollection regarding
the glowplug I broke off on #2, was that I didn't even put 30 ft-lb
on it.

Cynic: How would you know?

Answer: I've practiced tightening and loosening things from teenager to 
present, with a torque wrench, my favorite box and combo wrenches, etc.
In sports, it's called Muscle Memory.  A big part of golf, I am told by
sports trainers.  Well, slinging the wrench in the backyard is a sport.
(If you don't believe it, watch the sweat when you're losing.)

When you have a problem bolt, whether on a cylinder head, a vibration
damper pulley or a brake caliper, you apply penetrant, heat, shock, and
give it a few days, each day doing an application or two.  Shock can
be a light tap with a wrench, or a swing with a 5 lb hammer, depending
on what you're freeing up.  It becomes a game.  Like passing the ball 
around until someone lets a shot opportunity open up.

Scientifically, wetting agents and small molecules help.  I don't know
if fish oil (WD-40) is a bigger molecule than parafin, but my guess is
that parafin is smaller.  That's why the wax trick will work. Also, because
the wax isn't volatile, it doesn't dry out of the threads, and keeps 
lubricating as you get the threads starting to move.  On conventional steel
the thing you are trying to do is to colapse the rust matrix.  Oxides
of metals are harder and more brittle than the metal.  Al oxide is
used in sandpaper and saphires.  Shock, thermal and rapping with a 
wrench, helps break that matrix.

Developing a feel for when fasteners (or glowplugs) are starting to yield 
is a good thing.  Years ago, I developed surface metrology software
for a materials lab.  There I got to see Instron machines testing
materials, welds and other things.  Metals inelastically deform before
they break.  Cassie is right, if you see the hex on the glowplug
start to move without the base of the plug in the metal moving,
you're in real do-do.  Time to STOP, regroup, and reach into the 
arsenal.  

I've related this to Hagar, but every now and then I decide to save 
time, and not use impact, not use heat, and figure I can just take 
a stuck fastener off with a wrench.  I keep relearning the same lesson.
If it doesn't want to come with normal torque, something is wrong,
and it's time for penetrant, heat, impact and so on.

When I broke off #2 glowplug, I spent years trying to get it out
of there.  Using tire spoons applying pressure to extractors, and 
turning the extractors with wrenches on ground flats of a shortened 
extractor.  I never got it out, until the head came off.  Fortunately,
it remained intact, and never leaked forcing me to pull the head
prematurely.

Take a pile of some common hardware and break things.  1/4-20 bolts
are a good starting point.  They snap right off with a 7/16 wrench or
a rachet.  Feel the metal yielding.  It gets a inelastic sponge feeling.
When you've broken a few fastners, practice drilling them out.
It's easier to get good at extracting in the shop, than working
on a vehicle.  Access is limited, salt water is dripping in your face,
your hands have the gritty black grease formed by sand and sooty crankcase
oil.  

Enough.  I probably drive at least half of you nuts with the pencil tirades.
I just feel compelled to pass on the tricks that an old fart mechanic 
taught me when I was a kid.

Val



> From: cass <iscass at SHAW.CA>
> Subject: Re: [Vwdiesel] What is the candle wax GP extraction trick ?
> 
> i did this on a stuck and beginning to break glow plug.
> had sprayed it for days with liquid wrench
> to no avail.
> then took a propane torch..
> (everything elts on head was removed)
> and heated the area enuff to draw wax in
> along threads..
> when still warm..gently tapped wrench one way then the other..back n =
> fourth.
> left right.. tapped twice left..once right..
> till i felt it give a little.
> 
> finally out.
> had to do this to two gp's=20
> both stuck..both the 'nut' was beginning to turn and glow plug not
> ( beginning to break)
> 
> worked for me.
> i may have been lucky.
> have used wax many times.
> with a little heat.
> always seems to work.
> but maybe its the heat..and the time i take..not the wax?
> dunno.
> 
> cassie.
> from the wet rusty algae infested  west coast
> ( where the snow drops n=20
>  crocuses and irises are up :oD  )
>