[s-cars] AAN Spark Plug Back-out

[qshipq at aol.com]

 David


Until heat cycled, you can re-use and retorque a head bolt too...?
I know quite a few well known audi shops that use this spark plug
procedure, I routinely surveyed them a few years ago.? The
thinking (and this procedure was given the 'green light' by my contact
at Bosch) is that it's quite possible that there is a variance to the
crush washer 'tension' present for each hole condition, and the torque,
then retorque procedure (immediately following - read no heat cycle)
allows them all to more properly set to the conditions present in the
given port of entry.? The key IMO, is that the 22lb-ft(lb/ft,
pound feet, pound-feet, pound/feet) torque spec is used.? 





Then again, I too, am not a huge fan of the F5 for high boosted
motors.? IME, there is some quality control problems with them
which when under normal use, are within the fit for use
tolerance.? With high boost, I see a lot of the problems both Dave
and Hap described, as well as, hard to diagnose engine miss caused by
pinhole burns of the electrode casing.





I'm a huge fan of the TDC (triple copper) Bosch plugs, they are
virtually indestructable IME.? When going Platinum or irridium,
NGK has a better product, IMO.? IIRC, the neu S4 swapped to NGK
application.? 





HTH and my .02





Scott J












-----Original Message-----

From: David Forgie 

To: s-car-list 

Cc: QSHIPQ at aol.com

Sent: Thu, Nov 15  2:47 AM

Subject: [s-cars] AAN Spark Plug Back-out



  
    Scott:  I am not following your logic ("method in your madness") of your procedure:



"I use the same procedure many seasoned audi shops use,  torque all to 

22lb/ft.  Then go back 1 by 1 and loosen and retorque to  22lb/ft." 



(Note: I think the "lb/ft" should be lb ft, like Newton metres)



To me, backing the out the plug, manually, on purpose, kills the crush washer

and the when you go back in and retorque them there is no more crush washer

to provide what I thought is the required "tension" on  the threads, 

i.e. the crush washer acts a spring, pulling the upper side of the plug

threads against the lower side of the head threads.



What am I missing?



I am not being arguementative, I just don't understand why my thinking is 100%

the opposite of yours. 



Dave F. 

    
   


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