Cylinder Head Assembly: Service and Repair
Cylinder Head and ValvesREMOVAL AND INSTALLATION
Removal Steps 1-20:
REMOVAL SERVICE POINTS
PRECAUTION FOR REMOVED PARTS
1. keep removed parts in order according to the cylinder number and intake/exhaust.
A CYLINDER HEAD BOLTS REMOVAL
1. Using a 12 mm - 12 points socket wrench, loosen the cylinder head bolts. Loosen evenly, little by little.
B RETAINER LOCK REMOVAL
1. Store removed valves, springs and other parts, tagged to indicate their cylinder No. and location for reassembly.
C VALVE STEM SEAL REMOVAL
1. Do not reuse valve stem seal.
INSPECTION
CYLINDER HEAD
1. Check the cylinder head gasket surface for flatness by using a straightedge and thickness gauge.
Standard value: 0.05 mm (0.0020 in.)
Limit: 0.2 mm (0.008 in.)
2. If the service limit is exceeded, correct to meet the specification.
Grinding limit: *0.2 mm (0.008 in.)
* Includes/combined with cylinder block grinding.
Cylinder head height (Specification when new):
131.9-132.1 mm (5.193-5.201 in.) (DOHC)
VALVE
1. Check the valve face for correct contact. If incorrect, reface using valve refacer. Valve seat contact should be maintained uniform at the center of valve face.
2. If the margin exceeds the service limit, replace the valve.
VALVE SPRING
1. Measure the free height of spring and, if it is smaller than the limit, replace.
2. Measure the squareness of the spring and, if the limit is exceeded, replace.
Standard value:
2° or less (SOHC)
1.5° or less (DOHC)
Limit: Max. 4°
VALVE GUIDE
1. Measure the clearance between the valve guide and valve stem. If the limit is exceeded, replace the valve guide or valve, or both.
VALVE SEAT RECONDITIONING PROCEDURE
1. Before correcting the valve seat, check for clearance between the valve guide and valve and, if necessary. replace the valve guide.
2. Using the special tool or seat grinder, correct to obtain the specified seat width and angle.
3. After correction, valve and valve seat should be lapped with a lapping compound.
VALVE SEAT REPLACEMENT PROCEDURE
1. Cut the valve seat to be replaced form the inside to thin the wall thickness. Then, remove the valve seat.
2. Rebore the valve seat hole in the cylinder head to a selected oversize valve seat diameter.
Rework Dimensions:
Seat ring hole diameter: See "Rework Dimensions".
3. Before fitting the valve seat, either heat the cylinder head up to approximately 250 °C (482 °F) or cool the valve seat in liquid nitrogen, to prevent the cylinder head bore from galling.
4. Using a valve seat cutter, correct the valve seat to the specified width and angle.
See "VALVE SEAT RECONDITIONING PROCEDURE".
VALVE GUIDE REPLACEMENT PROCEDURE
1. Using the special tool and a press, remove the valve guide toward cylinder head gasket surface
2. Rebore valve guide hole to the new oversize valve guide outside diameter.
Rework Dimensions:
Valve guide hole diameter: See "Rework Dimensions".
NOTE: Do not install a valve guide of the same size again.
3. Using the special tool, press-fit the valve guide, working from the cylinder head top surface.
4. After installing valve guides, insert new valves in them to check for sliding condition.
5. When valve guides have been replaced, check for valve contact and correct valve seats as necessary.
INSTALLATION SERVICE POINTS
A VALVE STEM SEAL INSTALLATION
1. Install the valve spring seat.
2. The special tool must be used to install the valve stem seal. Improper installation could result in oil leaking past the valve guide.
CAUTION: Do not reuse the valve stem seal.
B VALVE SPRINGS INSTALLATION
1. Direct the valve spring end with identification color toward the spring retainer.
C RETAINER LOCK INSTALLATION
1. The valve spring, if excessively compressed, causes the bottom end of retainer to be in contact with, and damage, the stem seal.
D CYLINDER HEAD GASKET IDENTIFICATION
Identification mark:
4G63K (4G63 DOHC)
4G64K (4G64 DOHC)
E CYLINDER HEAD BOLT INSTALLATION
1. When installing the cylinder head bolts, check that the shank length of each bolt meets the limit. If the limit is exceeded, replace the bolt.
Limit: Max.
99.4 mm (3.91 in.) (DOHC)
2. Apply engine oil to the threaded portions of bolts and to the washers.
3. According to the tightening sequence, tighten the bolts to 78 Nm (58 ft.lbs.). Use with 12 mm - 12 points socket wrench.
4. Loosen bolts completely.
5. Retighten the loosened bolts to 20 Nm (14.5 ft.lbs.) in the specified tightening sequence.
6. Make a paint mark across each bolt head and cylinder head.
7. Give a 90° turn to the bolts in the specified tightening sequence.
8. Give another 90° turn to the bolts and make sure that the paint mark on the head of each bolt and that on the cylinder head are on the same straight line.
CAUTION:
1. If the bolt is turned less than 90°, proper fastening performance may not be expected. When tightening the bolt, therefore, be careful to give a sufficient turn to it.
2. If the bolt has been overtightened, loosen the bolt completely and then retighten it by repeating the tightening procedure from step (1).