Date:         Mon, 9 Sep 2002 09:25:36 -0600
Reply-To:     Ben McCafferty <ben@KBMC.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Ben McCafferty <ben@KBMC.NET>
Subject:      Summary:  Re: How hard is it to remove exhaust?
In-Reply-To:  <3D7BC873.D03EA6F2@sympatico.ca>
Content-type: text/plain; charset="US-ASCII"

You've gotten some good advice.  Let me summarize all this in a way that
(hopefully) makes some sense.
--Start by squirting the exhaust nuts (8 of them) with penetrating oil every
day for two weeks.

--On D-day, if you have the luxury, remove the engine.

--GENTLY try to remove each nut with a wrench or socket.  If there is any
significant resistance, STOP.

--Cut away the old exhaust (assuming you're replacing it) to give extra room
to work.  Ideally, cut away the flanges too, so you have an exposed stud and
nut.

--Try to borrow a nut splitter and split the remaining nuts.  I don't agree
with using a hammer and chisel for this part, as it's easy to bend/break a
stud.

--If you can't get to a nut to split it, you will have to try to remove it
with heat.  In this case, it is likely that you will back the stud out of
the head.  Using a propane torch, heat the head around the stud, not the
stud itself.  You will need to apply heat for 5 minutes or so.  Try to back
out the stud a little.  If it comes out, great.  If not, try tightening it
back in a little.  Go back and forth like this, still applying heat to the
head only.  Eventually it will either come out or you will pull the threads
out of the head with the stud.  If at any point the stud starts to feel
"soft", you're about to break it off.  The way to notice this is when you
are turning the wrench, and the stud tip is turning, but the base is not.
This is bad.  Stop, go get something to drink, call a friend, whatever.  Try
to get some experienced hands in there to help out.  If you shear a stud,
you will probably have to remove the head and take it to a machine shop,
where they can accurately drill the old stud, and re-thread the hole.
You can still use penetrating oil, but remember that it's flammable, so use
it between torch sessions, not during!  :)

--If you stripped the threads out of the head, use a Heli-Coil kit to
replace the threads.  These are expensive, but worth every penny.  The one
you need is M8x1.25.

--If you sheared the stud, you can take the head to a machine shop, or try
your hand at drilling the stud.  You will need a drill that has a low RPM
setting, and a bit suitable for mild steel.  Center punch the stud, then use
a small drill bit to begin drilling straight into the center of the stud.
When drilling steel, you should see two shavings making two corkscrews of
metal, coming up out of the hole.  If you have lots of little shavings, you
are drilling too fast, and you're polising (dulling) your bit.  It's very
easy to break off the drill bit, so be careful to support the drill.  Once
you've drilled in a ways, move to the next larger size drill bit.  Continue
this process until you have drilled out the center of the stud, leaving just
the threads.  At this point, you can try using an EZ-out to pull the threads
out.  Here again, do not use too much force with the EZ-out.  If you break
it off, you are guaranteed a visit to the machine shop, because the EZ-out
is made of a very hard alloy, and will require a carbide burr to drill out.
If the threads come out, great, you're ready for the new stud.  If not, I
would go ahead and drill out the threads in preparation for a heli-coil
insert.  You've already done most of the work, so just use the heli-coil
bit, then tap the hole and insert it.

--For the studs you didn't have to remove (if any), run the appropriate die
(M8x1.25) down the stud a few times to clean up the threads.  Be careful not
to cross-thread the die.

--When putting it all back together, use a good quality anti-seize compound
(I use permatex, aluminum based) on EVERYTHING.  Copper-based is great, I
just can't ever seem to find it.  This includes the 8 exhaust studs/nuts,
plus the j-tube bolts/nuts, and the muffler and tailpipe bolts/nuts.  I also
have a rule of thumb that says anytime I remove an exhaust bolt/nut for any
reason, I put new anti-seize on it as well.

--Use a torque wrench on everything, it's easy to over-tighten/strip these
parts.

--Hope this helps, best of luck.  Know that many knuckles have gone before
you, and we can all empathize with you.
tx,
bmc  :)

"Faith will move mountains, but you'd better bring a shovel...."