Hilicoil ate aluminum thread! Need help.

[Bob Rossato]

Along this vein.  As I recall, Konstantin, didn't you find a fair amount of
oil in the threaded hole when you first had the problem?  Was that ever
thoroughly cleaned out?  If not your problems may stem from trying to
compress an incompressible fluid when you're tightening the bolt.  The
result is the weakest link, the aluminum threads, will give way.

As for a stepped stud, how about part number 049 109 166.  I believe it is
an 8mm/6mm stepped stud used to hold on the timing belt covers on the VW
4cyl engines.  See item 9 on this image
http://catalog.exist.ru/pic/parts/VAG02226.gif.  Don't know if it is too
long but you could shorten it.  I have one in bin of left over bolts.

Bob

>
> Maybe the bolt is too long (wrong one?) and it is bottoming out
> in the hole, then when you keep turning it it becomes like a
> drill?  The same problem would repeat after helicoiling.
>
> It doesn't solve your problem on what to do, but it might be part
> of the cause?
>
> Just a thought.
>
> Ken
>
>
> Konstantin Bogach
>     konstantin.bogach at morganstanley.com
>
> Good people, My first experience with hilicoils turns to be not
> good.  I restored 6mm
> thread in aluminum (oil filter bracket, turbo oil supply flange), tried
> to torque the bolt and... bolt is eaten, thread in aluminum is eaten by
> helicoil.  I broke tang with hammer and rod. Visually was clear, bolt
> easily went in through helicoil all the way when I tried it.  Until I
> have a clue what happened I don't use helicol in aluminum any more.
> A problem grew into bigger problem.  Now I have bigger hole which might
> be OK for 8mm thread. Upper part of the hole is bigger then should be
> for 8mm tap (7.5 mm) but lower part (bigger than half)  is good. But I
> can not find stepped studs.  Dealer does not have it (at least one guy
> from parts told me that). Stores I called don't have them.  Any advice
> how to fix it or where to get 8 mm to 6mm studs? I appreciate
> your help. Konstantin Bogach.