friggin exhaust manifold studs!

[Jim Dupree]

I would look close at the threads in the cylinder head. I have seen the
threads pulled loose in the hole and it looks like an insert. It is was just
a small aluminum coil the was the threads in the hole to begin with. If
indeed your head has had heli-coils installed and they are pulling out or
stripped then there is a option still. They are called 'Big Serts'. They are
by the same company the makes Time-serts (better than heli-coils IMHO). It
is a thicker insert so you have to drill a larger hole than was required for
the heli-coil but you still get to use the original 8mm studs. You have to
get a kit, it comes with a drill, tap, insert and installation tool.
http://www.timesert.com/bigsert.html

I have never used one on an exhaust stud but I have used them in other
situations.
Good Luck
Jim
1993 S4
1984 4kq
1985 4kq
1985 5kt

----- Original Message ----- 
From: "Eric Sanborn" <eric_audi.ql at mindspring.com>
To: "Ameer Antar" <antar at comcast.net>
Cc: "Quattro List" <quattro at audifans.com>
Sent: Friday, July 02, 2004 4:09 AM
Subject: Re: friggin exhaust manifold studs!


> Ameer Antar wrote:
>
> > Ya, it looked like steel coiled inserts. They were all like that. When
> > I was tightening the studs in, I was a little worried about going too
> > deep as I didn't want to go too far and hit a water passage or
> > something. Each stud seemed to tighten a little differently..
> > depth-wise. So if the inserts are spinning that means they've come
> > undone, or what? What's the solution? Bigger thread? I don't think the
> > holes in the manifold will handle bigger bolts. What else? Can these
> > things be welded??? Man this is sounding scary!! HELP!!
> >
> > -Ameer
> >
> > ----Original Message----
> > From: Eric Sanborn <eric_audi.ql at mindspring.com>
> > Date: 7/1/04 11:01:18 PM
> > Subject: Re: friggin exhaust manifold studs!
> >
> > Ameer Antar wrote:
> >
> >> The threads in the head all looked like spiral-locks, but I figured
> >> that must be the design since it's an aluminum head, and all of em
> >> had it. Hope someone can offer some help... TIA.
> >>
> > Do you mean like helicols in each bolt hole?  I have never seen a VW
> > head with them.  I would guess it was a repair, but it would be
> > strange to have all of them that way.  Both my I-5 (KH, JT) are just
> > aluminum threads and my countless VW 4-cylinder heads are all just
> > aluminum.
> >
>
> The threaded inserts I have seen in the past require tapping to a
> special larger diameter and then installing the insert into the hole.
> The bottom of the insert has a small cross piece to it that the driver
> uses to install the insert.  Once the insert is fully seated this piece
> breaks off.  This allows you to thread your fastener deeper than the
> insert and I believe it locks the insert in place.
>
> When you turn the studs in the head to the inserts rotate also?  If so
> do they translate or thread into the and out of the head or just spin?
> If they just spin you have a problem.  If they translate in and out you
> might be able to work them out some and then loctite them back in.  Just
> don't go overboard on the amount of loctite or it will work to the ID of
> the helicoil and you will also be locking in your studs.
>
> If they just spin then they sound like they are stripped.  This is a
> problem since if they spin they will likely pull out during the first
> heat cycle of the exhaust manifold.  Remind me are the studs M8?  If so
> you would have to jump to M10 which is quite a jump.  I know it would be
> sad to mix and match, but maybe switching to 3/8" helicoils would work.
> A 3/8" bolt is 0.060" bigger in diameter where as M10 is 0.078".
> Remember that if you do you will have to insure that all the holes
> clearances remain unchanged.  The center two holes are fairly close
> fitting as they locate the manifold.  Every other hole has a loose fit
> to allow for thermal expansion.  Of course you would also have to find
> appropriate heavy washers.  I don't know if it can be done with the
> space allowed.
>
> I guess the most expensive option would be to weld the holes shut and
> then get them redrilled and tapped, but this would require the head off
> the block which would be I sure the last thing you want to do.
>
> One more option and this one would be classified as serious project
> scope creap.  Make your own manifold that can accept M10 studs.  Of
> course this means the CIS has to go in the garbage (where I wish mine
was).
>
> Keep me posted.  I feel for you.  These 11 hour problems on a big
> project can be disheartening.
>
> -- 
> Eric Sanborn
> '85 4ktq
>
> http://sofadog.net/4ktq/
>
>
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