Cylinder Head and Valves
CYLINDER HEAD AND VALVES
REMOVAL AND INSTALLATION
Required Special Tools:
^ MD998051: Cylinder Head Bolt Wrench
^ MD998712: Valve Spring Compressor
^ MD998774: Valve Stem Seal Installer
REMOVAL SERVICE POINTS
<> CYLINDER HEAD BOLT REMOVAL
Using special tool MD998051, loosen the cylinder head bolts.
Loosen each bolt evenly, little by little, by two or three steps.
<> RETAINER LOCK REMOVAL
1. Set special tool MD998772 as illustrated to compress the valve spring. Remove the retainer locks.
2. Relieve the spring tension and remove the valve, retainer, spring, etc. Store removed valves, springs and other parts, tagged to indicate their cylinder number and location for assembly.
INSTALLATION SERVICE POINTS
>>A<< VALVE STEM SEAL INSTALLATION
1. Install the valve spring seat.
CAUTION: The valve stem seal for the exhaust side is different than the intake side. They are identified by their respective rubber colors. When installing, do not confuse them.
CAUTION: The special tool must be used to install the valve stem seal. Improper installation could result in oil leaking past the valve guide.
2. Using special tool MD998774, install a new stem seal to the valve guide
>>B<< VALVE SPRING INSTALLATION
Install the valve spring with its ID color painted end (larger pitch side) upward (toward the valve spring retainer)
>>C<< RETAINER LOCK INSTALLATION
CAUTION: Do not compress the valve spring excessively. It can damage the stem seal.
1. Set special tool MD998772 as illustrated to compress the valve spring. Install the retainer locks
2. Relieve the spring tension and check that the retainer locks are seated correctly.
>>D<< CYLINDER HEAD BOLT INSTALLATION
1. Insert the cylinder head bolt with a washer attached into the bolt hole in the cylinder head. The washer must be set with the "rounded shoulder" side upward.
2. Tighten the cylinder head bolts to the specified torque in the sequence shown.
Tightening torque: 108 ± 5 Nm (80 ± 4 ft. lbs.)
3. Loosen all bolts fully.
4. Retighten the cylinder head bolts to the specified torque in the sequence shown.
Tightening torque: 108 ± 5 Nm (80 ± 4 ft. lbs.)
INSPECTION
CYLINDER HEAD
1. Check the cylinder head gasket surface for flatness by using a straightedge and feeler gauge in the directions of A through G shown in the illustration.
Standard value: 0.03 mm (0.0012 in.)
Limit: 0.2 mm (0.007 in.)
2. If it exceeds the limit, correct to meet the specification.
Grinding limit: *0.2 mm (0.007 in.)
*Includes combined with cylinder block grinding.
Cylinder head height (specification when new): 120 mm (4.7 inches)
VALVE
1. Check the valve seat contact. The valve seat contact should be uniform at the center of the valve face. If incorrect, reface using a valve refacer.
2. If the margin is below the limit, replace the valve.
Standard value:
Minimum limit:
3. Measure the valve's total length. If the measurement is less than the limit, replace the valve.
Standard value:
Minimum limit:
VALVE SPRINGS
1. Measure the free height of the springs. If it is less than the limit, replace.
Standard value: 51.0 mm (2.01 inches)
Minimum limit: 50.0 mm (1.97 inches)
2. Measure the squareness of the springs. If it exceeds the limit, replace.
Standard value: 2 degree angle or less
Limit: 4 degree angle
VALVE GUIDES
Measure the clearance between the valve guide and valve stem. If it exceeds the limit, replace the valve guide or valve, or both.
Standard value:
Limit:
VALVE SEAT
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: 49.30 mm (1.941 inches)
Limit: 49.80 mm (1.960 inches)
VALVE SEAT RECONDITIONING PROCEDURE
1. Before correcting the valve seat, check for the clearance between the valve guide and valve and, if necessary, replace the valve guide.
2. Using the special tool or a 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 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.
Intake seat ring hole diameter:
0.3 oversize 34.30 - 34.33 mm (1.3504 - 1.3516 inches)
0.6 oversize 34.60 - 34.63 mm (1.3622 - 1.3634 inches)
Exhaust valve seat ring hole diameter:
0.3 oversize 31.80 - 31.83 mm (1.2520 - 1.2531 inches)
0.6 oversize 32.10 - 32.13 mm (1-2638 - 1.2650 inches)
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. Remove the snap ring from the exhaust valve guide.
2. Using a press, remove the valve guide toward the cylinder block.
CAUTION: Do not install a valve guide of the same size again.
3. Rebore the valve guide hole of the cylinder head so that it fits the press-fitted oversize valve guide.
Valve guide hole diameter:
0.05 oversize 11.05 - 11.07 mm (0.4350 - 0.4358 in.)
0.25 oversize 11.25 - 11.27 mm (0.4429 - 0.4457 in.)
0.50 oversize 11.50 - 11.52 mm (0.4528 - 0.4535 in.)
4. Install the new snap ring into groove of the exhaust valve guide.
NOTE: The inlet valve guide has no snap ring groove.
5. Press-fit the valve guide until it protrudes 14.0 mm (0.55 in.) from the cylinder head top surface as shown in the illustration.
NOTE: When press-fitting the valve guide, work from the cylinder head top surface..
NOTE: After installing the valve guides, insert new valves in them to check for smooth operation.