Toyota Land Cruiser 1988 Repair Manual page 49

EM-18
ENGINE MECHANICAL-
Cylinder Head
EM4341
EM4336
EM4457
EM4340
6. INSPECT CYLINDER HEAD FOR FLATNESS
Using a precision straight edge and thickness gauge,
measure the surfaces contacting the cylinder block and
manifolds for warpage.
Maximum warpage:
Cylinder block side 0.15 mm (0.0059 in.)
Manifold side 0.10 mm (0.0039 in.)
If warpage is greater than maximum, replace the cylinder
head.
7. INSPECT CYLINDER HEAD FOR CRACKS
Using a dye penetrant, check the combustion chamber,
intake and exhaust ports, head surface and the top of the
head for cracks.
If cracked, replace the head.
8. CLEAN VALVES
(a) Use a gasket scraper, chip any carbon from the valve
head.
(b) Using a wire brush, thoroughly clean the valve.
9. INSPECT VALVE STEM AND GUIDE BUSHINGS
(a) Using a caliper gauge, measure the inside diameter
of the valve guide bushing.
Guide bushing inside diameter:
8.010-8.030 mm (0.3154- 0.3161 in.)