Head bolts - do not reuse!

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <350AA182.788F4F18@MCIONE.com> four.rings@MCIONE.com writes:

> I was abut to reuse the head bolts on my 200. Bentley explicitly allows
> to reuse the bolts on the 3B engine and does not say anything about the
> MC engine. I figured if a more stressed 3B does not break the once used
> head bolts, the MC is even less likely to do so.

> The new OEM bolt was right on the spec: M11x1.5x98mm.
> The old one was 3mm longer!!!

> Folks, don't listen to Bentley in this issue. If you pull the head -
> install new head bolts!

There are three takes on this; technical, practical and financial.
 
Technical:

Yes, the head bolts can be re-used _once_.  The non-elastic stretch that occurs 
on fitting can be tolerated exactly _twice_ by any given OEM bolt.  The reason 
for this (according to an engine designer) is that you might have to remove and 
replace the head _IN_ _AN_ _EMERGENCY_ when there are no spares available.

Practical:

No mechanism has been agreed for marking bolts that have already been re-used.  
Perhaps the bolts in your engine have already been re-used?  So - to paraphrase 
Clint Eastwood -just how lucky do you feel today?

Financial:

They cost _peanuts_.  I know there are half a dozen of so Qlisters for whom 
this is a non-trivial consideration, and for them I have sympathy.  More than 
you might imagine, just at the moment!  But for the others - $3 (tops) times 12?

-- 
 Phil Payne
 UK Audi [ur-]quattro Owners Club