Hilicoil ate aluminum thread! Need help.

[Konstantin Bogach]

You are right: the oil is what caused it.  The stepped stud you mentioned can
not be used because of that hex middle part.  I decided to to use time-sert
inserts.  Takes time to get them but this is really good solution, I think
best.  Maryland Metrics has threaded inserts too but they are much bulkier
then time-sert ones.  One hole though, is probably bigger then the insert and I
still need 6mm/8mm stud which I will use with 8mm insert.

Thanks to everyone who tried to help me with adivce.

Konstantin Bogach.

Bob Rossato wrote:

> 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.