Cylinder Head and Valves

REMOVAL AND INSTALLATION

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 the special tool, 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.

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 end 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

]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 inch)
2. Apply engine oil to the threaded portions of bolts and to the washers.





3. According to the tightening sequence, tighten the bolts to the specified torque 78 Nm (58 ft. lbs.) using special tool (MB991654).
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 is overtightened, loosen the bolt completely and then retighten it by repeating the tightening procedure from step (1).

INSPECTION

Cylinder Head





1. Check the cylinder head gasket surface for flatness by using a straightedge and feeler gauge.
Standard value: 0.05 mm (0.0020 inch)
Limit: 0.2 mm (0.008 inch)
2. If the service limit is exceeded, correct to meet specification.
Grinding limit: *0.2 mm (0.008 inch)
* Includes combined with cylinder block grinding.
Cylinder head height (Specification when new): 131.9 - 132.1 mm (5.193 - 5.201 inch)

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.





3. Measure the valve's total length. If the measurement is less than specified, replace the valve

Valve Spring





1. Measure the free height of spring and, if it is smaller than the limit, replace.
Standard value: 47.0 mm (1.850 inch)
Limit: 46.0 mm (1.811 inch)

2. Measure the squareness of the spring and, if the limit is exceeded, replace.
Standard value: 1.5° or less
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








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.

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 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 (refer to VALVE SEAT in INSPECTION).

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.
Intake seat ring hole diameters
0.3 O.S. 35.30 - 35.33 mm (1.3989 - 1.3909 inch)
0.6 O.S. 35.60 - 35.63 mm (1.4016 - 1.4028 inch)
Exhaust seat ring hole diameters
0.3 O.S. 33.30 - 33.33 mm (1.3110 - 1.3122 inch)
0.6 O.S. 33.60 - 36.63 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. See "VALVE SEAT RECONDITIONING PROCEDURE"

Valve Guide Replacement Procedure





1. Using the press, remove the valve guide toward the cylinder block.
2. Re-bore the valve guide hole of the cylinder head so that it may fit to the press-fitted oversize valve guide.

CAUTION: Do not install a valve guide of the same size again.

Valve guide hole diameters
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)





3. Press-fit the valve guide until it protrude 19.5 mm (0.77 inch) 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: 45.5 mm (1.79 inch); exhaust side: 50.5 mm (1.99 inch)]
3. After installing the valve guides, insert new valves in them to check for sliding condition.