cracked UrQ EM

[isham-research.freeserve.co.uk at pop.pol.net.uk]

> My UrQ is now making the classic Audi 5 cylinder cracked manifold "chuff
> chuff chuff." I noticed a slight ticking on startup on Saturday, and began to
> worry- then I autocrossed it yesterday.  Now it sounds like old truck.  I''ve
> forgotten-is the manifold an UrQ-only part? My questions are these:  Can I
> still get a new manifold (Audi or aftermarket)?  Are there good (better
> flowing?) aftermarket alternatives?  I know about the Dialynx manifolds'
> tendency to crack, so that's out.  Just wanted to see what the collective
> wisdom of the list thinks before I proceed :)  Thanks for any help/advice!

Despite all the claims, I'm not aware of a better manifold than Audi's.

They're very much still available (I fitted two last week) and somewhat
cheaper (at least in the UK) than they were.

The Dialynx manifold doesn't crack, it warps.  On hydraulic lifter
engines, like a wet board.  A Dialynx manifold wrecked my MB's first
head and I got the Big Red Bus GBP500 cheaper than market value
because it had a Dialynx manifold warping off an MC-2 head.  I had
to rebuild the head and it now has four helicoils and one stepped
stud.  A few weeks ago I gave three Dialynx manifolds to a UK club
member who wanted to hill-climb his car.

There was a court case in the UK today in which a club member sued
a workshop for some very bodged work.  Roger Galvin went down to
appear as a witness for the member - he and I wrote the initial report
on the car's condition.  Aelred (Dialynx) was also scheduled to appear
on behalf of the workshop, though I don't think it was entirely
voluntary.  A lot of the case centres around a Dialynx manifold that
has to be repeatedly retightened.

We've already had the suspension bolt issue today - this (exhaust)
issue is coincidentally another one that I've written about in the
November newsletter:

      Exhaust manifolds revisited

      We seem to bang on a lot about 10V exhaust manifolds,
      but then that's what they do in many members' cars.
      As we've said before, the primary cause of manifold
      cracking seems to be failure of the right engine
      mount causing the engine to sit on the subframe.  You
      can test for this by trying to pass a strip of paper
      around between engine and subframe.  The turbo is
      heavy and supported only by the manifold - if the
      mount has failed, road shocks are transmitted
      directly to the assembly like hammer blows.  In turn,
      the principle cause of engine mount failure seems to
      be the rusting away of the heatshield that should
      protect it from exhaust heat.  The problem doesn't
      affect the 20V engine because all the heat is much
      further away from the engine mount.  If its
      environment is correct (good mount, intact
      heatshield) there is no evidence that the original
      Audi 10V manifold has any undue liability to crack.
      Another source of problems is leakage, primarily
      caused by loose nuts, and this is where the story
      gets interesting.  First of all - a loose stud or nut
      is easy to detect on a cold car, because the thick
      washer underneath the nut can be turned with the tip
      of a finger.  But why do they come loose?  Here's the
      good bit - the spare parts microfiche (and the ETKA
      system now used by dealers) now lists a different set
      of exhaust manifold fasteners from that used in
      production.  The stud (N 900 717 02), washer (N 900
      955 01) and nut (N 902 002 01 - watch you don't get
      palmed off with inferior generic brass nuts) are the
      same - but a speednut (N 012 608 1) has been added to
      lock the primary nut in place.  If you do have the
      misfortune to have to replace a 10V manifold, specify
      that the fasteners, engine mount and heatshield
      should also be replaced (about GBP110) and that
      speednuts should be added - at 40 pence each they're
      cheap insurance.  Exhaust manifold studs should
      always be replaced - they're only 70 pence each and a
      major source of problems when reused.  And if your
      manifold isn't cracked, make sure you have the right
      engine mount checked at the next service - it's about
      three hours' labour to renew it.

--
 Phil Payne
 UK Audi quattro Owners Club
 Phone +44 7785 302803   Fax: +44 7785 309674