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DISASSEMBLY
11. INSPECT CAMSHAFT TIMING TUBE
a. Using a micrometer, measure the journal diameter.
Journal diameter: 39.955 - 39.964 mm (1.5730 - 1.5734 inch)
If the journal diameter is not as specified, check the oil clearance.
b. Install the timing tube to the intake camshaft, and check the timing tube turn smoothly.
If necessary, replace the timing tube and intake camshaft.
12. INSPECT CAMSHAFT GEAR SPRING
Using vernier calipers, measure the free distance between the spring ends.
Free distance: 18.2 - 18.8 mm (0.712 - 0.740 inch)
If the free distance is not as specified, replace the gear spring.
13. INSPECT CAMSHAFT BEARINGS
Check that bearings for flaking and scoring. If the bearings are damaged, replace the bearing caps and cylinder head as a set.
14. INSPECT CAMSHAFT AND CAMSHAFT TIMING TUBE JOURNAL OIL CLEARANCE
a. Install the camshaft timing tube to the intake camshaft.
b. Clean the bearing caps and journals.
c. Place the camshafts on the cylinder head.
d. Lay a strip of Plastigage across each of the journals.
e. Install the bearing caps.
NOTICE: Do not turn the camshaft.
f. Remove the bearing caps.
g. Measure the Plastigage at its widest point.
Standard oil clearance
Maximum oil clearance
If the oil clearance is greater than maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.
h. Completely remove the Plastigage.
i. Remove the camshafts.
j. Remove the camshaft timing tube from the intake camshaft.
15. INSPECT CAMSHAFT THRUST CLEARANCE
a. Install the camshaft timing tube to the intake camshaft.
b. Install the camshaft.
c. Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.
Standard thrust clearance
Maximum thrust clearance
If the thrust clearance is greater than maximum, replace the camshaft If necessary, replace the bearing caps and cylinder head as a set.
d. Remove the camshafts.
e. Remove the camshaft timing tube from the intake camshaft.
16. INSPECT CAMSHAFT GEAR BACKLASH
a. Install the drive gear to the camshaft timing tube.
b. Install the camshaft timing tube to the intake camshaft.
c. Install the camshafts without installing the exhaust camshaft sub-gear and front bearing cap.
d. Using a dial indicator, measure the backlash.
Standard backlash: 0.020 - 0.200 mm (0.0008 - 0.0079 inch)
Maximum backlash: 0.30 mm (0.0188 inch)
If the backlash is greater than maximum, replace the intake camshaft drive gear and exhaust camshaft.
e. Remove the camshafts.
f. Remove the camshaft timing tube from the intake camshaft.
g. Remove the drive gear from the camshaft timing tube.
17. INSPECT VALVE LIFTERS AND LIFTER BORES
a. Using a caliper gauge, measure the lifter bore diameter of the cylinder head.
Lifter bore diameter: 31.000 - 31.016 mm (1.2205 - 1.2211 inch)
b. Using a micrometer, measure the lifter diameter at the 12.5 ± 2.0 mm (0.492 ± 0.079 inch) from the top surface.
Lifter diameter: 30.968 - 30.976 mm (1.2192 - 1.2195 inch)
c. Subtract the lifter diameter measurement from the lifter bore diameter measurement.
Standard oil clearance: 0.024 - 0.048 mm (0.0009 - 0.0018 inch)
Maximum oil clearance: 0.07 mm (0.0028 inch)
If the oil clearance is greater than maximum, replace the lifter. If necessary, replace the cylinder head.
18. INSPECT UPPER INTAKE MANIFOLD
Using a precision straight edge and feeler gauge, measure the surface contacting the lower intake manifold for warpage.
Maximum warpage: 0.15 mm (0.0059 inch)
If warpage is greater than maximum, replace the upper intake manifold.
19. INSPECT LOWER INTAKE MANIFOLD
Using a precision straight edge and feeler gauge, measure the surface contacting the cylinder head and upper intake manifold for warpage.
Maximum warpage: 0.15 mm (0.0059 inch)
If warpage is greater than maximum, replace the lower intake manifold.
20. INSPECT EXHAUST MANIFOLD
Using a precision straight edge and feeler gauge, measure the surface contacting the cylinder head for warpage.
Maximum warpage: 0.50 mm (0.0197 inch)
If warpage is greater than maximum, replace the manifold.
REPLACEMENT
1. REPLACE VALVE GUIDE BUSHINGS
a. Gradually heat the cylinder head to 80 - 100°C (176 - 212°F).
b. Using SST and a hammer, tap out the guide bushing.
SST 09201-01055, 09950-70010 (09951-07100)
c. Using a caliper gauge, measure the bushing bore diameter of the cylinder head.
d. Select a new guide bushing (STD or O/S 0.05).
If the bushing bore diameter of the cylinder head is greater than 10.306 mm (0.4057 inch), machine the bushing bore to this dimension:
10.335 - 10.356 mm (0.4069 - 0.4077 inch)
If the bushing bore diameter of the cylinder head is greater than 10.356 mm (0.4077 inch), replace the cylinder head.
HINT: Different the bushings are used for the intake and exhaust.
e. Gradually heat the cylinder head to 80 - 100°C (176 - 212°F).
Using SST and a hammer, tap in a new guide bushing to the specified protrusion height.
SST 09201-01055, 09950-70010 (09951-07100)
Protrusion height (H)
g. Using a sharp 5.5 mm reamer, ream the guide bushing to obtain the standard specified clearance between the guide bushing and valve stem.
2. REPLACE SPARK PLUG TUBE GASKETS
a. Bend the 4 ventilation case claws installed on the cylinder head cover to an angle of 90° or more.
b. Using a screwdriver, pry out the gasket.
NOTICE: Be careful not to damage the cylinder head cover. Tape the screwdriver tip.
c. Using SST and a hammer, tap in a new gasket until its surface is flush with the upper edge of the cylinder head cover.
SST 09950-60010 (09551-00240, 09951-00440, 09952-06010), 09950-70010 (09951-07100)
NOTICE: Be careful of the installation direction.
d. Apply a light coat of MP grease to the gasket lip.
e. Return the 4 ventilation case claws to its original position.