Cylinder Head and Valves
REMOVAL AND INSTALLATION
[SOHC]
[DOHC]
Removal Service Points
Precaution For Removed Parts
[A] Cylinder Head Bolt Removal
1. Keep removed parts in order according to the cylinder number and intake/exhaust.
[B] Retainer Lock Removal
1. Using the special tool, compress the spring.
2. Remove the retainer locks.
[C] Valve Stem Seal Removal
1. Do not reuse removed valve stem seals.
Installation Service Points
]A[ Valve Stem Seal Installation
1. Install the valve spring seat.
2. Using the special tool, install a new stem seal to the valve guide
CAUTION:
1. Do not reuse removed valve stem seals.
2. Always use the special tool to install the valve stem seal. Improperly installed valve stem seal may cause oil down.
]B[ Valve Spring Installation
1. Direct the valve spring end with identification color toward the spring retainer
]C[ Retainer Lock Installation
1. Using the special tool, compress the valve spring and insert the retainer locks into position.
]D[ Cylinder Head Gasket Identification
CAUTION: Do not apply sealant to the cylinder head gasket.
Identification mark:
72S2 [SOHC]
72D4 [DOHC]
]E[ Cylinder Head Bolt Installation
1. Tighten the bolts in two to three stages in the illustrated sequence. Back off the bolts once and tighten them to the specified torque in the same procedure as shown in step (1).
CAUTION: Attach the head bolt washer in the direction shown in the figure.
INSPECTION
Cylinder Head
1. Check the cylinder head gasket surface for flatness by using a straightedge in the directions of A through G shown in the illustration.
Standard value:
0.05 mm (0.0020 inch) [SOHC]
0.03 mm (0.0012 inch) [DOHC]
Limit: 0.2 mm (0.008 inch)
2. If the service limit is exceeded, correct to meet the specification.
Grinding limit: *0.2 mm (0.008 inch)
* Total resurfacing depth of both cylinder head and cylinder block.
Overall height:
84 mm (3.31 inch) [SOHC]
132 mm (5.20 inch) [DOHC]
Valve
1. If the valve stem is worn (ridge wear) or otherwise damaged, replace. Also replace the valve if the stem end has a dent.
2. Check the valve face for correct contact. If incorrect, reface using a valve refacer. Valve should make a uniform contact with the seat at the center of valve face.
3. If the margin exceeds the service limit, replace the valve.
Standard value
SOHC
DOHC
Limit
SOHC
DOHC
4. Measure the overall length of the valve. If the specified limit is exceeded, replace the valve.
Standard value
SOHC
DOHC
Limit
SOHC
DOHC
Valve Springs
1. Measure the free height of the spring and, if it is smaller than the limit, replace.
Standard value
49.8 mm (1.96 inch) [SOHC]
46.4 mm (1.83 inch) [DOHC]
Limit
48.8 mm (1.92 inch) [SOHC]
45.4 mm (1.79 inch) [DOHC]
2. Measure the squareness of the spring and, if the limit is exceeded, replace.
Standard value: 2° or less
Limit: Max. 4°
Valve Guides
1. Measure the clearance between the valve guide and valve stem. If the limit is exceeded, replace the valve guide or valve, or both.
Standard value
SOHC
DOHC
Limit
Valve Seat
1. Assemble the valve, then measure the valve stem projection between the end of the valve stem and the spring seating surface. If the measurement exceeds the specified limit, replace the valve seat.
Standard value
SOHC
DOHC
Limit
SOHC
DOHC
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 correcting the valve seat, lap the valve and valve seat using lapping compound. Then, check the valve stem projection.
Valve Seat Replacement Procedure
1. Cut the valve seat to be replaced from 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.
Seat ring hole diameter:
SOHC
0.3 O.S. 44.30 - 44.33 mm (1.7441 - 1.7453 inch)
0.6 O.S. 44.60 - 44.63 mm (1.7559 - 1.7571 inch)
0.3 O.S. 38.30 - 38.33 mm (1.5079 - 1.5091 inch)
0.6 O.S. 38.60 - 38.63 mm (1.5197 - 1.5209 inch)
DOHC
0.3 O.S. 36.30 - 36.33 mm (1.4291 - 1.4303 inch)
0.6 O.S. 36.60 - 36.63 mm (1.4409 - 1.4421 inch)
0.3 O.S. 33.30 - 33.33 mm (1.3110 - 1.3122 inch)
0.6 O.S. 33.60 - 33.63 mm (1.3228 - 1.3240 inch)
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.
Valve Guide Replacement Procedure
1. Remove the snap ring from the exhaust valve guide. (SOHC)
2. Using a press, remove the valve guide toward the cylinder block.
3. Rebore the valve guide hole of the cylinder head so that it fits the press-fitted oversize valve guide.
CAUTION: Do not install a valve guide of the same size again.
Valve guide hole diameter:
[SOHC]
0.05 O.S. 15.05 - 15.07 mm (0.5138 - 0.5147 inch)
0.25 O.S. 15.25 - 15.27 mm (0.5217 - 0.5224 inch)
0.50 O.S. 15.50 - 15.52 mm (0.5315 - 0.5323 inch)
[DOHC]
0.05 O.S. 12.05 - 12.07 mm (0.4744 - 0.4752 inch)
0.25 O.S. 12.25 - 12.27 mm (0.4823 - 0.4831 inch)
0.50 O.S. 12.50 - 12.52 mm (0.4921 - 0.4929 inch)
4. Install the new snap ring into groove of exhaust valve guide.
5. Press-fit the valve guide until it protrudes 14.6 mm (0.57 inch) [SOHC] 17.5 mm (0.69 inch) [DOHC] from the cylinder head top surface as shown in the illustration.
NOTE:
1. When press-fitting the valve guide, work from the cylinder head top surface.
2. Pay attention to the difference in length of the valve guides. [intake side: 44.0 mm (1.73 inch); exhaust side: 48.0 mm (1.89 inch)] [SOHC] [intake side: 45.5 mm (1.79 inch); exhaust side: 50.5 mm (1.99 inch)] [DOHC]
3. After installing the valve guides, insert new valves in them to check for sliding condition.