Sounds like your socket is sliding down until you're turning both nuts
at the same time, rather than just the top one against the bottom one.
Would more nuts help?  You'd hope that there'd be a nut at the bottom
that's still able to hold against the torque you're adding with the socket.

On 5/20/2016 7:04 AM, Don Hanson wrote:
>    I have an inline VW motor (ABA Jetta block) with a couple of the exhaust
> manifold studs missing.  This motor is in my van using the diesel factory
> parts from the diesel Vans...50 degrees laid over.   I can get to all but
> two of  the exhaust manifold studs with box wrenches, but the two in the
> central cylinders I can only reach with multiple extensions and deep
> sockets while the motor is in the van....So...When I try to install those
> two central studs....It don't woik!    I've been counter-tightening two of
> the nuts, then running the stud down into the head, but I can't make it get
> tight...the two nuts will work down the stud and the threads on the stud
> won't thread far enough into the block to hold well...I have plenty of
> spare studs and nuts to work with from my cross flow extra head....I need a
> work around.   I don't fancy pulling the motor for this....
>
>   any ideas?   (besides pulling the motor and doing it right?)
>
> don hanson
>

toodle pip,
--
       Dug Smith          | Terry Pratchett: It's almost
(mailto:dug@dugbert.com) |  impossible to ride a rock and roll
(http://www.dugbert.com) |  motorbike and stay on for three verses.