Cylinder Head Assembly: Testing and Inspection

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 surfaces.

(b) Using a gasket scraper, remove all the gasket material from the cylinder block surfaces.
(c) Using compressed air, blow carbon and oil from the bolt holes.

WARNING: Protect your eyes when using high-compressed air.

2. Remove gasket material.
Using a gasket scraper, remove all the gasket material from the cylinder block contact surface.

CAUTION: Be careful not to scratch the cylinder block contact surfaces.

3. Clean combustion chambers.
Using a wire brush, remove all the carbon from the combustion chambers.

CAUTION: Be careful not to scratch the cylinder block contact surfaces.

4. Clean valve guide bushings.
Using a valve guide bushing brush and solvent, clean all the guide bushings.

5. Clean cylinder heads.
Using a soft brush and solvent, thoroughly clean the cylinder heads.

6. Inspect for flatness.
Using precision straight edge and feeler gauge, measure the surfaces contacting the cylinder block and manifolds for warpage.
Maximum warpage: 0.10 mm (0.0039 inch)
If warpage is greater than the maximum, replace the cylinder head.

7. Inspect for cracks.
Using a dye penetrant, check the combustion chamber, intake ports, exhaust ports and cylinder block surface for cracks.
If cracked, replace the cylinder head.

8. Clean valves.
(a) Using a gasket scraper, chip off any carbon from the valve head.
(b) Using a wire brush, thoroughly clean the valve.
9. Inspect valve stems and guide bushings.

(a) Using a caliper gauge, measure the inside diameter of the guide busing.
Bushing inside diameter: 6.010 - 6.030 mm (0.2366 - 0.2374 inch)

(b) Using a micrometer, measure the diameter of the valve stem.
Valve stem diameter:
Intake: 5.970 - 5.985 mm (0.2350 - 0.2356 inch)
Exhaust: 5.965 - 5.980 mm (0.2348 - 0.2354 inch)
(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 inch)
Exhaust: 0.030 - 0.065 mm (0.0012 - 0.0026 inch)
maximum oil clearance:
Intake: 0.08 mm (0.0031 inch)
Exhaust: 0.10 mm (0.0039 inch)
If the clearance is greater than the maximum, replace the valve and guide bushing.
10. 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.

NOTE: Wrap the tape approximately 8 mm (0.31 inch) from the valve stem end.

CAUTION: Be careful not to damage the valve lifter hole.

(b) Gradually heat the cylinder head to 80° - 100° C (176° - 212° F).

(c) Using Special Service Tool (SST) Valve Guide Bushing Remover & Replacer Set # 09201 - 10000 (Valve Guide Bushing Remover & Replacer 6 # 09201 - 01060), Handle Set # 09950 - 70010 (Handle 150 # 09951 - 07150) or equivalents and a hammer, tap out the guide bushing.

(d) Using a caliper gauge, measure the bushing bore diameter of the cylinder head.

(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 inch), machine the bushing bore to these dimensions: 11.050 - 11.077 mm (0.4350 - 0.4361 inch)
If the bushing bore diameter of the cylinder head is greater than 11.077 mm (0.4361 inch), replace the cylinder head.
(f) Gradually heat the cylinder head to 80° - 100° C (176° - 212° F).

(g) Using SST Valve Guide Bushing Remover & Replacer Set # 09201 - 10000 (Valve Guide Bushing Remover & Replacer 6 # 09201 - 01060), Handle Set # 09950 - 70010 (Handle 150 # 09951 - 07150) or equivalents and a hammer, tap in a new guide bushing until the snap ring makes contact with the cylinder head.

(h) Using a sharp 6 mm reamer, ream the guide bushing to obtain the standard specified clearance (See step 9) between the guide bushing and valve stem.
11. 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°

(c) Check the valve head margin thickness.
Standard margin thickness: 1.0 mm (0.039 inch)
Minimum margin thickness: 0.5 mm (0.020 inch)
If the margin thickness is less than the minimum, replace the valve.

(d) Check the valve overall length.
Standard overall length:
Intake: 95.15 mm (3.7461 inch)
Exhaust: 94.90 mm (3.7362 inch)
Minimum overall length:
Intake: 94.60 mm (3.7244 inch)
Exhaust: 94.40 mm (3.7165 inch)
If the overall length is less than the minimum, 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.

CAUTION: Do not grind off more than the minimum.

12. Inspect and clean valve seats.

(a) Using a 45° carbide cutter, resurface the valve seats. Remove only enough metal to clean the seats.

(b) Check the valve seating position.
Apply a thin coat of prussian blue (or white lead) to the valve face. Lightly press the valve against the seat. Do not rotate the 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.
^ If blue appears 360° around the valve seat, the guide and face are concentric. If not, resurface the seat.
^ Check that the seat contact is in the middle of the valve face with these widths: 1.0 - 1.4 mm (0.039 - 0.055 inch)
If not, correct the valve seats 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 60° and 45° cutters to correct the seat.

(d) Hand-lap the valve and valve seat with an abrasive compound.
(e) After hand-lapping, clean the valve and valve seat.
13. Inspect valve springs.

(a) Using a steel square, measure the squareness of the valve spring.
Maximum deviation: 2.0 mm (0.079 inch)
If deviation is greater than the maximum, replace the valve spring.

(b) Using vernier calipers, measure the free length of the valve spring.
Free length: 44.78 mm (1.7630 inch)
If the free length is not as specified, replace the valve spring.

(c) Using a spring tester, measure the tension of the valve spring at the specified installed length.
Installed tension:
At 33.3 mm (1.311 inch): 186 - 206 N (41.9 - 46.3 lbs.)
If the installed tension is not as specified, replace the valve spring.

14. 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: 0.06 mm (0.0024 inch)
If the circle runout is greater than the maximum, replace the camshaft.

15. Inspect cam lobes.
Using a micrometer, measure the cam lobe height.
Standard cam lobe height:
Intake: 42.31 - 42.41 mm (1.6657 - 1.6697 inch)
Exhaust: 41.96 - 42.06 mm (1.6520 - 1.6559 inch)
Minimum cam lobe height:
Intake: 42.16 mm (1.6598 inch)
Exhaust: 41.81 mm (1.6461 inch)
If the cam lobe height is greater than the maximum, replace the camshaft.

16. Inspect camshaft journals.
Using a micrometer, measure the journal diameter.
Journal diameter: 26.949 - 26.965 mm (1.0610 - 1.0616 inch)
If the journal diameter is not as specified, check the oil clearance.

17. Inspect camshaft bearings.
Check the bearings for flaking and scoring.
If the bearings are damaged, replace the bearing caps and cylinder head as a set.

18. Inspect camshaft gear spring.
Using a vernier caliper, measure the free distance between the spring end.
Free distance: 18.2 - 18.8 mm (0.712 - 0.740 inch)
If the free distance is not as specified, replace the gear spring.
19. Inspect camshaft journal oil clearance.
(a) Clean the bearing caps and camshaft journals.
(b) Place the camshafts on the cylinder head.

(c) Lay a strip of Plastigage across each of the camshaft journals.
(d) Install the bearing caps.
Torque: 16 Nm (12 ft. lbs.)

CAUTION: Do not turn the camshaft.

(e) Remove the bearing caps.

(f) Measure the Plastigage at its widest point.
Standard oil clearance: 0.035 - 0.072 mm (0.0014 - 0.0028 inch)
Maximum oil clearance: 0.10 mm (0.0039 inch)
If the oil clearance is greater than the maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.
(g) Completely remove the Plastigage.
20. Inspect camshaft thrust clearance.
(a) Install the camshafts.

(b) Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.
Standard thrust clearance: 0.033 - 0.080 mm (0.0013 - 0.0031 inch)
Maximum thrust clearance: 0.12 mm (0.0047 inch)
If the thrust clearance is greater than the maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.
21. Inspect camshaft gear backlash.
(a) Install the camshafts without installing the exhaust camshaft sub-gear.

(b) 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 the maximum, replace the camshafts.
22. 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 - 31.018 mm (1.2205 - 1.2212 inch)

(b) Using a micrometer, measure the lifter diameter.
Lifter diameter: 30.966 - 30.976 mm (1.2191 - 1.2195 inch)
(c) Subtract the lifter diameter measurement from the lifter bore diameter measurement.
Standard oil clearance: 0.024 - 0.052 mm (0.0009 - 0.0020 inch)
Maximum oil clearance: 0.08 mm (0.0031 inch)
If the oil clearance is greater than the maximum, replace the lifter. If necessary, replace the cylinder head.
23. Inspect intake manifold, exhaust manifolds, air intake chamber and intake air connector.

(a) Intake Manifold:
Using precision straight edge and feeler gauge, measure the surfaces contacting the cylinder head and intake air connector for warpage.
Maximum warpage: 0.10 mm (0.0039 inch)
If warpage is greater than the maximum, replace the intake manifold.

(b) Exhaust Manifolds:
Measure the surfaces contacting the cylinder head for warpage.
Maximum warpage: 1.00 mm (0.0394 inch)
If warpage is greater than the maximum, replace the exhaust manifold.

(c) Air intake chamber and intake air connector:
Measure the surfaces contacting the intake manifold and intake air connector for warpage.
Maximum warpage: 0.10 mm (0.0039 inch)
If warpage is greater than the maximum, replace the air intake chamber or intake air connector.
24. If necessary, replace spark plug tube gaskets.

(a) Bend up the tab on the ventilation baffle plate which prevents the gasket from the slipping out.
(b) Using a screwdriver and hammer, tap out the gasket.

CAUTION: Do not scratch or damage the joint of the cylinder head cover.

(d) Using a 32 mm socket wrench and hammer, tap in a new gasket until its surface is flush with the upper edge of the cylinder head cover.
(e) Apply a light coat of Multipurpose (MP) grease to the gasket lip.
(f) Return the ventilation plate tab to its original position.