Apologies for re-opening this old thread but wanted to correct some reported repair errors.
The lower inlet manifold also carries the top coolant rail but being plastic doesn't transmit the heat to inlet tracts. It takes six individual soft rubber gaskets with grooves to allow accurate placement. The upper inlet manifold sits above secured by screws into threaded inserts on lower. This takes two rubber gaskets, one for each bank, again located by grooves. It would be possible to fit any of these gaskets incorrectly though which is likely what happened in the OP's case during Ford's engine build and clearly nothing MMC could have caused or prevented since engine supplied to them complete. The correct cure would be to fit fresh gasket(s) correctly inserted not glued! Lower inlet manifold (shown inverted) and full gasket set (Elring 856.670) below.
![[Linked Image]](https://i.imgur.com/q95P59o.jpg)
![[Linked Image]](https://i.imgur.com/R1G6yN1.jpg)