Hi S-Class, Mercedes recommend that the static setting of the hydraulic lifters (valve lash compensating elements) be checked at 40K. intervals and that if the clearances do not fall between the limits applicable, different size shims are to be used.
If that is insufficient information for you, I will endeavour to scan some further details for you.
Incidentally, I have further news that I can convey, although at this stage:
1) I am ubable to supply pics as the battery of the camera had gone "kabunk", and
2) Photobucket did not allow me to choose a file for illustration purposes.
I have since re-logged and , at least, the last named problem has been rectified.
Anyway, you may recall the 'puff-puff' from the exhaust which primarily seemed to be prevalent only when idling - well, I have looked at the underside of the inlet manifold and the fuel chamber, and there are very obvious signs of petrol (brown and moist) leakage from the seal that connects the two halves. Picture to come.
Furthermore, I can also tell you that valve recession should never be a problem on 450's and 6.9's - there is ample automatic compensation provided by the hydraulic lifters. So, maybe the problem you have with your red AMG 6.9 could well be in the same area as I have referred to. Regards Styria