Re: exhaust manifold stud replacement

[mike posner <posne@cts.com>]

At 10:29 AM 5/29/97 UT, Colin Barfoot wrote:
>The repair for my circumferentially cracked turbo exhaust to downpipe weld
was 
>started last night that looks like it will be ok.
>When checking the exhaust manifold studs re the exhaust leak there I found 
>fully 7 studs were sheared off. (New record perhaps?)
>So as recommended by this list the intake manifold, turbo,wastegate etc will 
>come off to see if the studs can be drilled in situ or else the head will
come 
>off.
>Those who have drilled in situ (dremel tool I remember) are there any
special 
>thinks to be careful of?
>It was suggested that I machine the manifold for flatness, any specs? or
other 
>work do do while machining?!...
>If I have to remove the head is there any special R&R I should do while it
is 
>off? Is there anything I should check on the turbo etc.  The car has 305,000 
>km, (I know, I know, still low mileage).
>One good think is this will be the ideal time to install my new TAP samco
hose 
>and turbo blowby valve..:)
>Thanks in Advance!
>Colin
>86 5000 CD Quattro
>still :^)
>I'd advise against trying to drill studs out "in situ" with the head on as
getting it wrong is very easy when you're working in very close quarters
and the costs of having to heliarc a botched hole(s) will be pricey. I know
from a recent experience on my turbo Volvo. I'd certainly  consider whether
you need a valve job , timing belt and h20 pump, turbo condition if you
have to r&r the head it is the ideal time. Broken exhaust studs is endemic
in these turbo engines with red hot temperatures being the norm as well as
vibration,
but what I think is the most most difficult problem to control is the
loosening
of the fasteners due these conditions. Self lockening nuts are self loosening
under these conditions.  Ive attempted to wire lock the critical areas, and
use locking tabs as well to see if this will slow down the process.Good luck.