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II. Engine Component Description
Cylinder Head
The 4IRJ7N cylinder heads are cast iron with
replaceable valve guides and valve seats.
Compression tests are conducted using a
compression gauge adapter used as a glow plug
insert, special tool number 54368709.
Refer to workshop manual for procedure.
The compression service limit for this engine is
370 psi (26.0 kg/cm 2 ). Standard pressure is 441
psi (31.0 kg/cm 2 ). IR allows an 8% variance
between neighboring cylinders on compression
tests, but there can be no more than a 15%
difference between any two cylinders.
Letters A-F represent the different
measurements that need to be taken to
determine head warpage.
Lower face warpage specifications:
Standard: 0.05 mm. (0.002 in.)
Limit: 0.2 mm. (0.008 in.)
Max Grinding Allowance: 0.3 mm. (0.0118 in.)
Head Height:
Standard: 91.95 92.05mm. (3.620 3.624 in.)
Limit: 91.65 mm. (3.61 in.)
IMPORTANT: Valve depression must be
checked to ensure that it is still within
specification.
NOTE: The head gasket and torque angle
head bolts cannot be reused.
