Cylinder Head Assembly: Service and Repair
COMPONENTS
DISASSEMBLY
1. Using the special tool (09221 - 32001), loosen the cylinder head bolts.
Fig. 3 Cylinder Head Bolt Removal:
2. Slowly loosen the cylinder head bolts in the sequence shown in the illustration.
3. Using the special tool, valve spring compressor, remove the retainer locks.
4. Put these parts in order so they can be reinstalled in their original positions.
5. Remove the valve stem seals with pliers and discard them.
NOTE: Do not reuse valve stem seals.
INSPECTION
1. Remove scale, sealing compound and carbon deposits. After cleaning oil passages, apply compressed air to make certain that the passages are not clogged.
2. Visually check the cylinder head for cracks, damage or water leakage.
3. Check the cylinder head surface for flatness with a straight edge and feeler as shown in illustration.
Standard value: Max. 0.05 mm (0.002 inch)
Limit: 0.20 mm (0.008 inch)
Valve Guides
Check the valve stem-to-guide clearance. If the clearance exceeds the service limit, replace the valve guide with a new oversize guide.
Valve stem-to-guide clearance:
Standard valve:
Intake: 0.03 - 0.06 mm (0.0012 - 0.0024 inch)
Exhaust: 0.05 - 0.09 mm (0.0020 - 0.0035 inch)
Limit:
Intake: 0.10 mm (0.0039 inch)
Exhaust: 0.15 mm ( 0.0059 inch)
Valve
1. Replace the valve stem if it is worn (stepped, worn or damaged). Also replace if the stem end (the surface contacting the auto-lash adjuster) is recessed.
2. Check the valve face contact area, and recondition or replace as necessary.
3. Replace the valve if the width of the margin (thickness of the valve head) is less than the minimum specified.
Valve Margin:
Standard value:
Intake side: 1.2 mm (0.047 inch)
Exhaust side: 2.0 mm (0.079 inch)
Limit:
Intake side: 0.7 mm (0.028 inch)
Exhaust side: 1.5 mm (0.059 inch)
Valve Spring
1. Check free height of each valve spring and replace if necessary.
2. Using a square, test the squareness of each valve spring. If a spring is excessively out of square, replace it.
Valve Spring:
Standard value:
Free height: 50.5 mm (1.988 inch)
Load: 32.9kg/40.4 mm (74 lbs./1.591 inch)
Out of squareness: Max. 2°
Limit:
Free height: 49.5 mm (1.949 inch)
Load: 32.9kg/41.4 mm (74 lbs./1.630 inch)
Out of squareness: Max. 40°
Valve Seat Reconditioning
1. Before reconditioning, check the valve guide for wear. Replace worn guide if necessary, then recondition the valve seat.
2. To recondition the valve seat, use the Valve Seat Cutter and Pilot.
3. After reconditioning, the valve and valve seat should be lapped lightly with a lapping compound.
4. Check valve seat insert linkage. If the sinkage exceeds the service limit, replace the insert with an oversize insert.
5. Measure the installed height of the spring between the spring seat and the retainer with the valve spring seat, spring retainer and retainer lock installed. The amount of sinkage can be judged from the measured value. which is the installed height of spring A for intake, exhaust.
Standard value: 40.4 mm (1.591 inch)
Limit: 41.4 mm (1.630 inch)
REASSEMBLY
1. Install the spring seats.
2. Using the special tool (09222 - 32100), lightly tap the seal into place.
NOTE:
- Do not reuse old valve stem seals.
- Incorrect seal installation could result in oil leaking down the valve guides.
3. Apply engine oil to each valve. Insert valves into guides. Avoid forcing the valve into the seal. After installing the valve, check that it moves smoothly.
4. Valve springs should be installed with the enamel coated side toward the valve spring retainer.
5. Using the special tool, compress the spring and install the retainer locks. After installing the valves, ensure that the retainer locks are correctly in place before releasing the valve spring compressor.
NOTE: When the spring is compressed, check that the valve stem seal is not pressed against the bottom of the retainer.
6. Clean both gasket surfaces of the cylinder head and cylinder block.
7. Verify the identification marks on the cylinder head gasket.
8. Position the gasket surface with the identification mark towards the cylinder head.
NOTE: Do not apply sealant to these surfaces.
Fig. 14 Cylinder Head Bolt Tightening Sequence:
9. Torque the cylinder head bolts in the sequence shown in the illustration with the special tool and a torque wrench.
10. When tightering the cylinder head bolts, repeat the sequence 2 or 3 times, each time increasing the torque until the specified torque is reached.
Tightening torque:
Cylinder head bolts Cold (Engine coolant temperature approximately 20°C [68°F]): 105 - 115 Nm (1050 - 1150 kgs.cm, 76 - 83 ft. lbs.)
VALVE CLEARANCE ADJUSTMENT
As the intake and exhaust valves are equipped with auto-lash adjustment mechanisms, there is no need for valve clearance adjustment. The proper functioning of the auto-lash mechanism may be determined by checking for valve noise. When there is valve noise or any unusual noise, check the auto-lash by removing and bleeding or replacing it.