RE: Reuse of head bolts ...

["frank j. bauer" <frankbauer@thevine.net>]

At 01:32 PM 11/22/99 -0800, Dupree, Jim wrote:
>At the VW/Audi engine rebuilding training course I took it was made quite
>clear to us that the 6 pt bolts were no longer to be used, replace them with
>new 12 pt bolts anytime the bolts were removed. The 12 pt bolts are indeed
>stretch bolts and that is why they must be replaced in complete sets,
>apparently they stretch slightly different each time and a mixed set of new
>and old bolts would give uneven clamping force on the head. The 12 pt bolts
>are reusable, I don't know how many times a set can safely be reused. 
>According to Audi/VW the 6 pt bolts were also reusable, but they were not
>stretch bolts and they were not as reliable and consistent for even clamping
>forces. 
>And yes the 12 pt bolts DO NOT require re-toque after 1000 miles except the
>diesel engines.
>Six pt bolts DO require re-torque after 1000 miles since they don't stretch
>they can not compensate for the slight compression of the head gasket that
>occurs in the first 100 miles.
>I have reused many sets of 12 pt head bolts and I know of no failures
>related to the bolts.

based on all the assertions and opinions i have heard on the subject in the
past few days, this sounds like the best (most comprehensive) explanation yet.

i will be replacing mine as a complete set since i slightly tweaked one of
the 12-point heads due to a misaligned tool during removal.
a set of 12 (includes the thick washers) from the parts connection is less
than $20 shipped...

frank