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