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II. Engine Component Description
Cylinder Head Gasket
The 4IRJ7N engine uses a three layer ultra
thin laminated steel head gasket that comes
pre-coated with a silicon material.
Holes for coolant are drilled between the
valve seats for effective cooling of the
combustion area. The sealing bead
surrounding the cylinders of the gasket is
stainless steel. It protects the head gasket
from the high cylinder pressures.
The cylinder head gasket is available in
three grades (thickness), identifiable by the
punched Grade Mark. The appropriate
head gasket grade is selected according to
the average measured piston projection. A
good rule of thumb is that unless you are
machining the deck, replace with the same
grade (thickness) of gasket that came out.
During installation, the TOP mark of the
gasket must be facing up and no additional
application of sealers or gasket adhesives is
necessary. In addition, no re-torqueing of
the head bolts is required after the engine
break-in period if the prescribed angular
tightening method is used.