Cylinder Head Assembly: Service and Repair
COMPONENTS
DISASSEMBLY
Tightening Sequence:
1. Using the special tool, Cylinder Head Bolt Wrench (09221 - 32001), remove the cylinder head bolts as shown in the illustration.
2. Using the special tool, Valve Spring Compressor (09222 - 28000, 09222 - 28100), remove the retainer lock. Next, remove the spring retainer, valve spring, spring seat and valve.
NOTE: Keep these parts in order so they can be reinstalled in their original Positions.
3. Remove the valve stem seals with pliers, and discard.
NOTE: Do not reuse the valve stem seals.
INSPECTION
Cylinder head
1. Check the cylinder head for cracks, damage and coolant leakage. If cracked, replace the cylinder head.
2. Remove scale, sealing compound and carbon. After cleaning oil passages, apply compressed air to ensure that passages are not clogged.
3. Check the cylinder head surface for flatness in the direction of A, B. as shown in illustration. If flatness exceeds service limit in any direction, either replace the cylinder head, or lightly machine the cylinder head gasket surface.
Standard value:
Cylinder head surface flatness:
Less than 0.005 mm (0.002 inch)
Limit:
Cylinder head surface flatness: 0.1 mm (0.0040 inch)
Valves
1. Using a wire brush, clean the valve thoroughly.
2. Check each valve for wear, damage and distortion of head and stem at B. Repair or correct, if necessary. If stem end A is pitted or worn, resurface as necessary. This correction must be limited to a minimum. Also resurface the valve face.
Replace the valve if the margin has decreased to less than the service limit.
Margin:
Standard value:
Intake: 1.0 mm (0.040 inch)
Exhaust: 1.5 mm ( 0.059 inch)
Limit:
Intake: 0.7 mm (0.028 inch)
Exhaust: 1.0 mm ( 0.040 inch)
Valve Springs
1. Check the valve spring free length and tension. If they exceed the service limit, replace the spring.
2. Using a square, test the squareness of each spring. If a spring is excessively out of square, replace it.
Valve Spring:
Standard value:
Free height: 48.3 mm (1.902 inch)
Load: 300N (66 lbs.) 40 mm (1.575 inch)
Out of square: Less than 1.5°
Limit:
Free height: -1.0 mm (-0.039 inch)
Out of square: 4°
Valve Guides
Check the valve stem-to-guide clearance. If the clearance exceeds the service limit, replace the valve guide with the next oversize part.
Valve stem-to-guide clearance:
Standard value:
Intake: 0.020 - 0.047 mm (0.0008 - 0.0019 inch)
Exhaust: 0.050 - 0.085 mm (0.0020 - 0.0033 inch)
Limit:
Intake: 0.1 mm (0.0040 inch)
Exhaust: 0.15 mm (0.0059 inch)
Valve Seat Insert
Check the valve seat for evidence of overheating and improper contact with the valve face. Recondition or replace the seat if necessary.
Before reconditioning the seat, check the valve guide for wear. if the valve guide is worn, replace it, then recondition the seat. Recondition the valve seat with a valve seat grinder or cutter. The valve seat contact width should be within specifications and centered on the valve face.
REASSEMBLY
NOTE:
1) Clean each part before assembly.
2) Apply engine oil to sliding and rotating parts.
1. After installing the spring seat, fit the stem sea' onto the valve guide.
To install, fit the seal in by lightly tapping the Special Tool, Valve Stem Oil Seal Installer.
The seal is installed in the specified position by means of the special tool. Incorrect installation of the seal will adversely affect the lip l.D. and eccentricity, resulting in oil leaking down the valve guides. Therefore, when installing, be careful not to twist the seal. Do not reuse old stem seals.
2. Apply engine oil to each valve. Insert the valves into the valve guides. Avoid using force when inserting the valve into the seal. After insertion, check to see if the valve moves smoothly.
3. Install springs and spring retainers. Valve springs should be installed with the enamel coated side toward the valve spring retainer.
4. Using the special tool, Valve Spring Compressor, remove the retainer lock. Next, remove the spring retainer, valve spring, spring seat and valve.
NOTE: Keep parts in order so they can be reinstalled in their original positions.
5. Clean all cylinder block and cylinder head gasket surfaces.
6. Install a new cylinder head gasket onto the cylinder head assembly. Do not apply sealant to the gasket, and do not reuse the old cylinder head gasket.
Tightening Sequence:
7. Using the special tool, Cylinder Head Bolt Wrench (0922132001), install the cylinder head bolts as shown in the illustration
Cylinder head bolt (cold engine): 90 - 100 Nm (900 - 1000 kgs.cm, 65 - 72 ft. lbs.)
LASH ADJUSTERS CHECK
If abnormal noise is heard from the lash adjusters (tappets), check as follow;
1. While installed to the cylinder head, press the part where the rocker arm contacts the lash adjuster at the very top. If the adjuster is normal, the part pressed will feel very hard.
2. If it easily moves all the way downward when pressed, there is a malfunction of the lash adjuster and it should be replaced with a new one.
3. If it feels spongy or elastic, probably oil with air mixed in it has entered the lash adjuster, so follow the steps below:
- Check whether the amount of oil is too much or is not enough.
- Check whether the cause of air becoming mixed into the oil is a damaged oil screen or oil screen gasket. After repairing the cause of the air leak, warm up the engine and then drive the vehicle at low speed for a while.
4. Stop the engine and leave it off for a few minutes, then re-start the engine and drive at low speed. Re-start this procedure several times during the course of about one hour so as to remove the air from the oil.