Ford 2003 Mustang Workshop Manual page 1260

Both cylinder heads
58. CAUTION: Do not use metal scrapers, wire brushes, power abrasive discs or other
abrasive means to clean the sealing surfaces. These tools cause scratches and gouges
that make leak paths. Use a plastic scraping tool to remove all traces of the head gasket.
CAUTION: Observe all warnings or cautions and follow all application directions
contained on the packaging of the silicone gasket remover and the metal surface prep.
NOTE: If there is no residual gasket material present, metal surface prep can be used to clean
and prepare the surfaces.
Clean the cylinder head-to-cylinder block mating surfaces of both the cylinder head and the
cylinder block.
1. Remove any large deposits of silicone or gasket material with a plastic scraper.
2. Apply silicone gasket remover, following package directions, and allow to set for several
minutes.
3. Remove the silicone gasket remover with a plastic scraper. A second application of
silicone gasket remover may be required if residual traces of silicone or gasket material
remain.
4. Apply metal surface prep, following package directions, to remove any remaining traces
of oil or coolant, and to prepare the surfaces to bond with the new gasket. Do not attempt
to make the metal shiny. Some staining of the metal surfaces is normal.
59. NOTE: The straightedge used must be flat within 0.0051 mm (0.0002 in) per foot of tool length.
Support the cylinder head on a bench with the head gasket side up. Inspect all areas of the
deck face with a straightedge, paying particular attention to the oil pressure feed area. The
cylinder head must not have depressions deeper than 0.0254 mm (0.001 in) across a 38.1 mm
(1.5 in) square area, or scratches more than 0.0254 mm (0.001 in) .