Date: Wed, 21 Feb 2001 11:02:19 -0500
Reply-To: Robert Donalds <bostneng@FCL-US.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Robert Donalds <bostneng@FCL-US.NET>
Subject: hardware and torqueing was Flexing cranks and Yielding Bolts one
last time
Content-Type: multipart/alternative;
Ken
As you know I glass bead some engine parts and heads when I rebuild them
I learned long ago that blind holes collect and trap glass bead. the
problem with this is that the bolt hole is shorter when the bottom is
full of glass bead and just as you thing the bolt is tight it brakes off
in your hand. using used parts and hardware can be tricky the lessons
we have learned are the bolts we have broken but they are only a lesson
if we learn something. I do a couple of things to clean and check
threaded holes. first I make sure the parts are dry before I glass bead
them. second I blow the hole out with air pressure always with safety
goggles. third I chase the hole with a thread chaser or a fairly new tap
(I dont trust old taps) and I use a taping fluid. taps tend to remove
metal and can weaken threads new hardware is always a good idea as is
wire brushing any old bolts that must be reused. it is way easier and
faster to go to the hardware store for new bolts and nuts than to go to
the hardware store for drills and tap extractors. If you are not sure
that a nut is tight to begin with or that a bolt is not all the way down
in the hole then TAKE IT APART AND CHECK IT OUT
a couple of problems I have seen worth pointing out on the vanagon
engines
the bolt for the front pulley locks up before the pulley is tight I cant
explain why this keeps coming up but I have had to chase the threads in
the crank and add washers to get the pulley secure there does not seem
to be more than one bolt length
the head nuts as you mentioned can twist and moan as they get torqued
and they even snap off if the stud is rusted.
you cant add oil and sealant to the threads it will never seal. I chase
the threads and inspect the blind hole in the head nut and tap it out if
needed I always run a wire bottle brush threw the head nut threads. When
the head nuts bind I remove the nut and add a small amount of sealant to
the threads as a lube keep in mind that any sealant that gets between
the top of the stud and the nut has the potential to bind and give a
false reading as to the torque values. one last note I have have seen
the AMC heads strip the threads for the exhaust when the exhaust is
installed and the bolt is tightened the problem is not the heads but the
bolt is to short I use a 30 mm lenght bolt and a flat washer I may not
look like it will tighten but it does for this reason all my engines
come with the hardware to hang the exhasut on the heads
Bob Donalds
http://www.bostonengine.com
as always
all rights reserved
KENWILFY@aol.com wrote:
> Bob, thanks for sharing. It is always great to learn something new
> and I did
> today. I want your opinion on something though. I had always been
> told in
> Aviation Mechanics School that when you torque fasteners you do not
> use any
> lubrication unless the manual specified it. However in the article,
> what
> this guy says makes sense. How can you know that the resistance you
> are
> getting and that is being measured by the torque wrench is not just
> the
> resistance of a stubborn fastener instead of the fastener actually
> being
> tight? I never used any lube when putting waterboxer head nuts on
> simply
> because nothing in Bentley talks about it. Should I be using 30 wt
> oil?
> What has your experience been?
>
> Thanks,
> Ken Wilford
> John 3:16
> www.vanagain.com
> Phone: (856)-765-1583
> Fax: (856)-327-2242
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