Disassembly and Assembly

Disassembly





Right bank





Left bank

1. Remove camshaft bracket.
Loosen and remove bolts following the order shown in the figure.
Mark the installation position before removing camshaft bracket.
Inspect camshaft end play before loosening camshaft bracket bolts.
2. Remove camshaft.
3. Remove rocker arm.





4. Remove hydraulic lash adjuster.
If hydraulic lash adjuster is kept on its side, there is a risk of air entering it. After removal, always set hydraulic lash adjuster in upright position. Otherwise, place it in a container of engine oil when laying it on its side.
- Do not disassemble hydraulic lash adjuster.
- Attach tags to valve lifters so as not to mix them up.





5. Remove valve collets.
Use valve spring compressor (suitable tool) and remove valve collets.
6. Remove valve spring retainers, valve springs and valve spring seats.
7. Remove valves.
Before removing valves, inspect gap between valve guides and check valve stem protrusion distance.

Inspection

CYLINDER HEAD DISTORTION
Clean surface of cylinder head.
Use a reliable straightedge and feeler gauge to check the flatness of cylinder head surface.





Check along six positions shown in the figure.
Head surface flatness:
Standard Less than 0.03 mm (0.0012 inch)
Limit 0.1 mm (0.004 inch)
If beyond the specified limit, replace it or resurface it.
Resurfacing limit:
The limit for cylinder head resurfacing is determined by the cylinder block resurfacing.
Amount of cylinder head resurfacing is "A".
Amount of cylinder block resurfacing is "B".
The maximum limit is as follows: A + B = 0.2 mm (0.008 inch)
After resurfacing cylinder head, check that camshaft rotates freely by hand. If resistance is felt, cylinder head must be replaced.
Nominal cylinder head height: 130.7 - 130.9 mm (5.146 - 5.154 inch)

CAMSHAFT VISUAL CHECK
Check camshaft for scratches, seizure and wear.

CAMSHAFT RUNOUT





1. Measure camshaft runout at the center journal.
Runout (Total indicator reading):
Standard Less than 0.02 mm (0.0008 inch)
Limit 0.05 mm (0.0020 inch)
2. If it exceeds the limit, replace camshaft.

CAMSHAFT CAM HEIGHT





1. Measure camshaft cam height.
Standard cam height:
Intake 37.858 - 38.048 mm (1.4905 - 1.4979 inch)
Exhaust 34.969 - 35.159 mm (1.3767 - 1.3842 inch)
Cam wear limit:
Intake & Exhaust 0.05 mm (0.0020 inch)
2. If wear is beyond the limit, replace camshaft.

CAMSHAFT JOURNAL CLEARANCE
1. Install camshaft bracket and tighten bolts to the specified torque.





2. Measure inner diameter of camshaft bearing.
Standard inner diameter: 26.000 - 26.021 mm (1.0236 - 1.0244 inch)





3. Measure outer diameter of camshaft journal.
Standard outer diameter: 25.935 - 25.955 mm (1.0211 - 1.0218 inch)
4. If clearance exceeds the limit, replace camshaft and/or cylinder head.
Camshaft journal clearance:
Standard 0.045 - 0.086 mm (0.0018 - 0.0034 inch)
Limit 0.15 mm (0.0059 inch)

CAMSHAFT END PLAY
1. Install camshaft in cylinder head.





2. Measure camshaft end play.
Camshaft end play:
Standard 0.070 - 0.148 mm (0.0028 - 0.0058 inch)
Limit 0.20 mm (0.0079 inch)

CAMSHAFT SPROCKET RUNOUT
1. Install sprocket on camshaft.





2. Measure camshaft sprocket runout.
Runout (Total indicator reading): Less than 0.25 mm (0.0098 inch)
3. If it exceeds the limit, replace camshaft sprocket.

VALVE GUIDE CLEARANCE





1. Measure valve deflection in a parallel direction with rocker arm. (Valve and valve guide mostly wear in this direction.)
Valve deflection limit (Dial gauge reading):
Intake & Exhaust 0.15 mm (0.0059 inch)





2. If it exceeds the limit, check valve to valve guide clearance.
a. Measure valve stem diameter and valve guide inner diameter.
b. Check that clearance is within specification.





Valve to valve guide clearance

c. If it exceeds the limit, replace valve or valve guide.

VALVE GUIDE REPLACEMENT





1. To remove valve guide, heat cylinder head to 110 to 130°C (230 to 266°F).





2. Drive out valve guide with a press [under a 20 Nm (2 ton, 2.2 US ton, 2.0 Imp ton) pressure] or hammer and suitable tool.





3. Ream cylinder head valve guide hole.
Valve guide hole diameter (for service parts):
Intake 11.175 - 11.196 mm (0.4400 - 0.4408 inch)
Exhaust 12.175 - 12.196 mm (0.4793 - 0.4802 inch)





4. Heat cylinder head to 110 to 130°C (230 to 266°F) and press service valve guide onto cylinder head.
Projection "L": 17.15 - 17.35 mm (0.6725 - 0.6831 inch)





5. Ream valve guide.
Finished size:
Intake 7.000 - 7.018 mm (0.2756 - 0.2763 inch)
Exhaust 8.000 - 8.011 mm (0.3150 - 0.3154 inch)

VALVE SEATS
Check valve seats for pitting at contact surface. Resurface or replace if excessively worn.
- Before repairing valve seats, check valve and valve guide for wear. If they have worn, replace them. Then correct valve seat.





- Use both hands to cut valve seat uniformly.

REPLACING VALVE SEAT FOR SERVICE PARTS





1. Bore out old seat until it collapses. Set machine depth stop so that boring cannot contact bottom face of seat recess in cylinder head.
2. Ream cylinder head recess.
Reaming bore for service valve seat
Oversize [0.5 mm (0.020 inch)]:
Intake 39.500 - 39.516 mm (1.5551 - 1.5557 inch)
Exhaust 34.500 - 34.516 mm (1.3583 - 1.3589 inch)
Use the valve guide center for reaming to ensure valve seat will have the correct fit.
3. Heat cylinder head to 110 to 130°C (230 to 266°F).
4. Press fit valve seat until it seats on the bottom.
5. Cut or grind valve seat using suitable tool at the specified dimensions as shown under Engine; Specification; Mechanical.
6. After cutting, lap valve seat with abrasive compound.





7. Check valve seating condition.
Seat face angle "a": 44°53' - 45°07' degree
Contacting width "W":
Intake 1.05 - 1.35 mm (0.0413 - 0.0531 inch)
Exhaust 1.25 - 1.55 mm (0.0492 - 0.0610 inch)





8. Use a depth gauge to measure the distance between the mounting surface of the cylinder head spring seat and the valve stem end. If the distance is shorter than specified, repeat step 5 above to adjust it. If it is longer, replace the valve seat with a new one.
Valve seat resurface limit "L":
Intake 46.25 - 46.95 mm (1.8209 - 1.8484 inch)
Exhaust 46.21 - 46.91 mm (1.8193 - 1.8468 inch)

VALVE DIMENSIONS





Check dimensions in each valve. For dimensions, refer to Engine; Specifications; Mechanical.
When valve head has been worn down to 0.5 mm (0.020 inch) in margin thickness, replace valve.
Grinding allowance for valve stem tip is 0.2 mm (0.008 inch) or less.

VALVE SPRING

Squareness





1. Measure dimension "S".
Out-of-square "S": Less than 2.0 mm (0.079 inch)
2. If it exceeds the limit, replace spring.

Pressure





Check valve spring pressure at specified spring height.
Pressure:
Standard 535.5 N (54.6 kg, 120.4 lbs.) at height 26.8 mm (1.055 inch)
Limit More than 477.6 N (48.7 kg, 107.4 lbs.) at height 26.8 mm (1.055 inch)
If it exceeds the limit, replace spring.

HYDRAULIC LASH ADJUSTER
1. Check contact and sliding surfaces for wear or scratches.





2. Check diameter of lash adjuster.
Outer diameter: 16.980 - 16.993 mm (0.6685 - 0.6690 inch)





3. Check lash adjuster guide inner diameter.
Inner diameter: 17.000 - 17.020 mm (0.6693 - 0.6701 inch)
Standard clearance between lash adjuster and adjuster guide: 0.007- 0.040 mm (0.0003 - 0.0016 inch)

Inspection of air entering
- Check if air has entered inside of hydraulic lash adjuster when it is installed or if abnormal sound occurs when engine is running.





- Press rocker arm pivot firmly around the cam base circle as shown in figure.
Depression limit: 1.0 mm (0.039 inch)
- If depression dimension is greater than 1.0 mm (0.039 inch), air may have entered the high-pressure chamber of hydraulic lash adjuster. Perform the following procedures to bleed air from the adjuster.

Air bleeding





- Remove hydraulic lash adjuster. Place adjuster in container of engine oil. While pressing plunger down as shown in the figure, lightly press check ball with a narrow rod.
- Air bleeding is accomplished when the plunger is pressed and does not spring back.

CAUTION:
- Be especially careful not to damage the check ball.
- If air bleeding does not remove air, replace the hydraulic lash adjuster assembly.
- Do not disassemble hydraulic lash adjuster.

Assembly





1. Install valve component parts.
- Always use new valve oil seal.
- Before installing valve oil seal, install valve spring seat.
- Install valve spring (uneven pitch type) with its narrow pitch side toward cylinder head side (Paint mark).
- After installing valve components, tap valve stem tip with a plastic hammer to assure a proper fit.