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CYLINDER HEAD COMPONENTS
INSPECTION, CLEANING AND REPAIR
1. CLEAN TOP SURFACES OF PISTONS AND
CYLINDER BLOCK
(a) Turn the crankshaft, and bring each piston to top dead
center (TDC). Using a gasket scraper, remove all the
carbon from the piston top surface.
(b) Using a gasket scraper, remove all the gasket material
from the cylinder block surface.
(c) Using compressed air, blow carbon and oil from the
bolt holes.
CAUTION: Protect your eyes when using high pressure
compressed air.
2. CLEAN CYLINDER HEAD
A. Remove gasket material
Using a gasket scraper, remove all the gasket material
from the cylinder block contact surface.
NOTICE: Be careful not to scratch the cylinder block
contact surface.
B. Clean combustion chambers
Using a wire brush, remove all the carbon from the
combustion chambers.
NOTICE: Be careful not to scratch the cylinder block
contact surface.
(c) Using needle±nose pliers, remove the oil seal.
± 5S±FE ENGINEENGINE MECHANICALEG1±55
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3. INSPECT CYLINDER HEAD
A. Inspect for flatness
Using a precision straight edge and thickness gauge,
measure the surfaces contacting the cylinder block
and the manifolds for warpage.
Maximum warpage:
Cylinder block side
0.05 mm (0.0020 in.)
Manifold side
0.08 mm (0.0031 in.)
If warpage is greater than maximum, replace the cylin±
der head.
B. Inspect for cracks
Using a dye penetrant, check the combustion cham±
bers, intake ports, exhaust ports and cylinder block
surface for cracks.
If cracked, replace the cylinder head. D. Clean cylinder head
Using a soft brush and solvent, thoroughly clean the
cylinder head. C. Clean valve guide bushings
Using a valve guide bushing brush and solvent, clean
all the guide bushings.
± 5S±FE ENGINEENGINE MECHANICALEG1±56
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(c) Subtract the valve stem diameter measurement from
the guide bushing inside diameter measurement.
Standard oil clearance:
Intake
0.025 ± 0.060 mm (0.0010 ± 0.0024 in.)
Exhaust
0.030 ± 0.065 mm (0.0012 ± 0.0028 in.)
Maximum oil clearance:
Intake
0.08 mm (0.0031 in.)
Exhaust
0.10 mm (0.0039 In.)
If the clearance is greater than maximum, replace the
valve and guide bushing. (b) Using a micrometer, measure the diameter of the
valve stem.
Valve stem diameter:
Intake
5.970 ± 5.985 mm (0.2350 ± 0.2356 in.)
Exhaust
5.965 ± 5.980 mm (0.2348 ± 0.2354 In.) 5. INSPECT VALVE STEMS AND GUIDE BUSHINGS
(a) Using a caliper gauge, measure the inside diameter of
the guide bushing.
Bushing inside diameter:
6.010 ±6.030 mm (0.2366 ± 0.2374 in.) 4. CLEAN VALVES
(a) Using a gasket scraper, chip off any carbon from the
valve head.
(b) Using a wire brush, thoroughly clean the valve.
± 5S±FE ENGINEENGINE MECHANICALEG1±57
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6. IF NECESSARY, REPLACE VALVE GUIDE
BUSHINGS
(a) w/ Snap Ring:
Insert an old valve wrapped with tape into the valve
guide bushing, and break off the valve guide bushing
by hitting it with a hammer. Remove the snap ring.
HINT: Wrap the tape approx. 8 mm (0.31 in.) from the
valve stem end.
NOTICE: Be careful not to damage the valve lifter hole.
(e) Select a new guide bushing (STD size or O/S 0.05).
If the bushing bore diameter of the cylinder head is
greater than 11.027 mm (0.4341 in.), machine the
bushing bore to the following dimension:
11.050 ± 11.077 mm (0.4350 ± 0.4301 in.)
If the bushing bore diameter of the cylinder head is
greater than 11.077 mm (0.4361 in.), replace the
cylinder head.(b) Gradually heat the cylinder head to 80±1005C (176±
2125F).
(d) Using a caliper gauge, measure the bushing bore di±
ameter of the cylinder head. (c) Using SST and a hammer, tap out the guide bushing.
SST 09201±70010
Bushing bore diameter
mm (in.)
11.050 ± 11.077
(0.4350 ± 0.4361) 11.000 ± 11.027
10.4331 ± 0.4341)Both intake and exhaust
Use O/S 0.05Bushing size
Use STD
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(c) Check the valve head margin thickness.
Standard margin thickness:
0.8 ± 1.2 mm (0.031 ± 0.047 in.)
Minimum margin thickness:
0.5 mm (0.020 in.)
If the margin thickness is less than minimum, replace
the valve. 7. INSPECT AND GRIND VALVES
(a) Grind the valve enough to remove pits and carbon.
(b) Check that the valve is ground to the correct valve
face angle.
Valve face angle:
44.5 (g) Using SST and a hammer, tap in a new guide bushing
until the snap ring makes contact with the cylinder
head.
SST 09201± 70010
(h) Using a sharp6 mm reamer, ream the guide bushing
to obtain the standard specified clearance (See page
EG1±57) between the guide bushing and valve stem. (f) Gradually heat the cylinder head to 80 ±100 C (117 ±
212F).
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(d) Check the valve overall length.
Standard overall length:
Intake
97.60 mm (3.8425 in.)
Exhaust
98.45 mm (3.8760 in.)
Minimum overall length:
Intake
97.1 mm (3.823 in.)
Exhaust
98.0 mm (3.858 in.)
If the overall length is less than minimum, replace the
valve.
(b) Check the valve seating position.
Apply a light coat of prussian blue (or white lead) to
the valve face. Lightly press the valve against the
seat. Do not rotate valve.
(c) Check the valve face and seat for the following:
If blue appears 360 around the face, the valve is
concentric. If not, replace the valve. (e) Check the surface of the valve stem tip for wear.
If the valve stem tip is worn, resurface the tip with a
grinder or replace the valve.
NOTICE: Do not grind off more than minimum.
8. INSPECT AND CLEAN VALVE SEATS
(a) Using a 45 carbide cutter, resurface the valve seats.
Remove only enough metal to clean the seats.
± 5S±FE ENGINEENGINE MECHANICALEG1±60
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wIf blue appears 360 around the valve seat, the
guide and face are concentric. If not, resurface
the seat.
wCheck that the seat contact is in the middle of the
valve face with the following width:
1.0 ± 1.4 mm (0.039 ± 0.055 in.)
If not, correct the valve seat as follows:
(1) If the seating is too high on the valve face, use
30 and 45 cutters to correct the seat.
(2) If the seating is too low on the valve face, use
75 and 45 cutters to correct the seat.
9. INSPECT VALVE SPRINGS
(a) Using a steel square, measure the deviation of the
valve spring.
Maximum deviation:
2.0 mm (0.079 in.)
If the deviation is greater than maximum, replace the
valve spring.
(b) Using a vernier caliper, measure the free length of the
valve spring.
Free length:
41.96 ± 41.99 mm (1.6520 ± 1.6531 in.)
If the free length is not as specified, replace the valve
spring. (d) Hand±lap the valve and valve seat with an abrasive
compound.
(e) After hand±lapping, clean the valve and valve seat.
± 5S±FE ENGINEENGINE MECHANICALEG1±61
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B. Inspect cam lobes
Using a micrometer, measure the cam lobe height.
Standard cam lobe height:
Intake
42.01 ± 42.11 mm (1.6539 ± 1.6579 in.)
Exhaust
40.06 ± 40.18 mm (1.5772 ± 1.5811 In.)
Minimum cam lobe height:
Intake
41.90 mm (1.6496 in.)
Exhaust
39.95 mm (1.5728 in.)
If the cam lobe height is less than minimum, replace
the camshaft. 10. INSPECT CAMSHAFTS AND BEARINGS
A. Inspect camshaft for runout
(a) Place the camshaft on V ± blocks.
(b) Using a dial indicator, measure the circle runout at the
center journal.
Maximum circle runout:
0.04 mm (0.0016 in.)
If the circle runout is greater than maximum, replace
the camshaft.(c) Using a spring tester, measure the tension of the valve
spring at the specified installed length.
Installed tension:
164 ± 189 N (16.7 ± 19.3 kgf, 36.8 ± 42.5 lbf)
at 34.7 mm (1.336 in.)
If the installed tension is not as specified, replace the
valve spring.
C. Inspect camshaft journals
Using a micrometer, measure the journal diameter.
Journal diameter:
26.959 ± 28.975 mm 11.0814 ± 1.0620 in.)
If the journal diameter is not as specified, check the oil
clearance.
± 5S±FE ENGINEENGINE MECHANICALEG1±62