Date:         Fri, 2 May 1997 01:31:08 -0400
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         j.ettorre@utoronto.ca
Subject:      Re: 84 Head Bolt/Nut leak



On Thu, 1 May 1997 thunkler@juno.com wrote:
> 
> I would also like to know the following dimensions, hopefully before I
> take the headnuts off..  
> 
> 1.)  Hole diameter in head for headbolts.

I remember 11 or 12mm, but the heads that I had are gone (long story. 
It's a school project)

> 
> 2.)  Diameter across threads,  and shank of head bolts.
> 
The threads are M12, I beleive. If you can 
find a Machinery's Handbook, this will give you the answer. The pitch 
used here is the regular one (1.75mm). The stud diameter is 11.7mm. If my 
memory is bad (i'll check), I'll re-post the answer again.


> a) Scribe a line on headnut to head for reference.
> b) Take torque wrench and see what  present torque is by,
>         first recording tightening"breakaway" torque,  then loosen 1/8
> turn and tighten back           to scribed line and record that torque

I'm not sure that this will yield conclusive answers (look he's talking 
like an engineer already), because if it's cracked, there is only a small 
possibility of closing it: by unloading the stud completely, which obviously 
you wouldn't want to do. Also, someone has already given you their way to 
fix it.

> c) Remove nut and stuff an o-ring of appropriate size ? into space to
> stop coolant from     leaking.

In Theory (hey, you might care), this would change the torque control of 
the clamping away from what "they" intended. The head/nut friction looks 
like it would be reduced, so the clamping would be higher. This assumes 
the o-ring didn't get destroyed and completely squeezed out when it was 
clamped.


> d) Dry and clean the area and headnuts.
> 
> e) Use yellow "dealer" sealant and apply liberally to joint area and
> headnut surface.
> 
> f) Torque to measured value in b above.
> 
> g) Due the same to the other leak.
> 
> 
> 
> I can see all kinds of potential for problems either causing more leaks

The O-ring might do this

> or perhaps setting the head up for cracking later.  

It sounds like it's already busted. Do the cracks go from the inside corner of
the nut-flat toward the spark-plug hole (or the opposite way)?. These are 
often aluminum-welded closed

> 
> Thanks,
> 
> Tom Hunkler
> thunkler@juno.com
> 1984 Vanagon 1.9   142k  
>