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Re: Exhaust manifault studs



MSV96 wrote:
> 
> Hi Igor,

> Excellent advice!!! Now back to my first question...how do you get to them????
> I have not yet ventured there on any of my Audis but fear I will need to
> before too long on my 87 5kcstq. Any advice you can pass along will be much
> appreceated! TIA...

Mike,
I've done it 4 times on 3 cars.

1. My own n/a '85 5000s. Studs #11 and #12. Happened for the first time
and scared the life out of me (zero Audi experience then). I was afraid
to touch anything on that car so I managed to: 
a)centre punch the remainder of the stud; 
b)drill a 1/8" hole in it with a B&D Skewdriver (an angle screwdriver
gizmo); 
c)easyout the broken piece.
 
The fun part was doing it without removing ANYTHING at all. Neither the
head, nor the intake or the exhaust manifolds. It took a rather
elaborate improvised sys of mirrors and an angle drill to get around the
intake manifold, but then again, it was a n/a KZ engine.
The car's engine bay was so empty (in comparison with the MC engine)
that one could play football in it.

2. Same car, two years later. Blew the head gasket (6 hours prior to the
Christmas trip to Fla and the associated 20+ hrs drive. Audi Gods looked
after that car :-).
Drove to Fla in the "backup" car (Mitsu Mirage. BTW, it also blew the
gasket a few mos later, but unlike the Audi, it happened at only 95kmi.
So much for the alleged reliability of the Japanese cars ;-)
Came back to Philly, pulled the head off the Audi, drilled the studs
out. Once at this, replaced the valve seals with the Viton (green) ones;
naturally, also lapped the valves and resleeved the spark plug holes
with the threaded inserts (I half stripped the thread on one out of five
by accident).
Of course doing it on a bench was a piece of cake.

3. I inherited broken #1 and #2 studs with my 200 when I bought it . The
access to the front studs (unlike to the rears on my 5000s) was very
easy: I just removed the grill, interccoler, airbox, RH headlight,
intake manifold, wastegate, downpipe and turbo. BTW, the top front nut
on the turbo flange is an absolute b*tch to remove. One needs a short
17mm wrench and even then can only do 1/32 of a turn at a time.

The trouble hit me in the end: I broke the Craftsdude easyout, flush in
the stud. That SOB was made out of some very hard steel, I musta broken
a dozen carbide drill bits trying to get it out.

NEVER EVER USE WEDGE SHAPED (NON SPIRAL) EASYOUTS! They are impossible
to back
out by unscrewing! If you break it you are in for a "Project"!

I also messed up the head coz the drill bit walked off the carbide
easyout and into the soft Al.

All of these had prompted me to design and machine a  shaped (a
Cyrillic equivalent of the Latin letter "P") brass tool with four holes
mimicking one flange of the EM. Three holes were used for securing the
tool to the three EM studs, whereas for the 4th one I machined a set of
teflon rollers. All of them had the same O.D. (equivalent to the DIA of
the 4th hole) but the I.D. of their respective bores were different as
to accommodate various drill bits, needed for using in conjunction with
different easyouts.

With that tool secured to 3 studs I MILLED(!) a 10mm cavity in where the
broken stud together with the broken easy out was. I then cut a 1/2-20"
tread in that cavity with the help of a bottoming tap. Then I screwed in
a threaded insert (1/2-20" O.D. by 8x1.25mm I.D.) into which I fitted a
new forged EM stud.

Fellows, be extra careful with the easyouts! The restoration of just one
messed
up hole had taken the better part of a week!

4. My friends '87 5000s. Did it on the car, only this time it was more
difficult coz the friend's wife didn't give a damn about the roaring
exhaust. The mfld had been warping and was breaking the studs one by one
at a steady rate. 3(!) studs were broken in succession. The job still
turned out to be a piece of cake coz I already had the tool described
hereabove, so I just drilled the studs out by using the method of
successive approximations (mathematically speaking). I.e. put it on 3
studs, secured it with the nuts, inserted a roller in the fourth hole.
Drilled the hole in the 4th stud using the roller as an absolutely
fool-proof centering tool. Removed the broken stud with an easyout.

Screwed a new stud into this newly restored hole, removed the tool, put
the tool on the next group of 3 studs, this time including the newly
restored one and
repeated the procedure. All in all had taken a few minutes per hole max,
piece of cake.

Oh, the EM had been bent SEVERELY, one could see the warpage with a
naked eye even without applying a steel ruler true to the 3rd flange.
I had to take the EM to the machine shop at my Co and ask my machinist
buddy to true it for me on the CNC (Bridgeport). No, I did not do it
myself. Setting up with an indicator a fancy shaped cast iron EM in the
machine so that the #1 and #5 flanges are on the same height and yet
true parallel to the horizontal feed of the machine took a lot of time
even for our very experienced machinist. Cutting itself was fast and
easy.

Bottom line: it is a fairly simple and strait forward job. Especially on
a n/a motor. I see absolutely no need to remove the head for this
operation.
All you need is an angle  drill and a set of good industrial duty spiral
easyouts.

-- 
Igor Kessel
'89 200TQ -- 18psi (TAP)
'98 A4TQ -- FINALLY!
Philadelphia, PA
USA