Cylinder Head and Valves
CYLINDER HEAD AND VALVESREMOVAL AND INSTALLATION
Removal Steps 1-20:
Required Special Tools:
^ MB991614: Angle Gauge
^ MB992085: Valve Stem Seal Plier
^ MB992182: Valve Stem Seal Installer
^ MD998735: Valve Spring Compressor
REMOVAL SERVICE POINTS
[[A]] RETAINER LOCK REMOVAL
1. Using special tool MD998735, compress the spring.
2. Remove the retainer locks.
[[B]] VALVE STEM SEAL REMOVAL
Using the special tool MB992085, nip the valve stem seal and remove it.
INSTALLATION SERVICE POINTS
]]A[[ VALVE STEM SEAL INSTALLATION
1. Install the valve spring seat to the valve guide.
CAUTION:
^ Valve stem seals for intake valves and for exhaust valves are different. Be sure to install the correct ones.
^ Valve stem seal identification color.
Intake: GRAY
Exhaust: GRAY GREEN
CAUTION:
^ Always use the special tool to install the valve stem seal. Improperly installed valve stem seals may leak oil.
^ Do not strike the valve stem seal strongly because it might be damaged.
2. Using special tool MB992182, install a new stem seal to the valve guide.
NOTE: After install, check the special tool does not stick to the valve spring sheet. Put the valve spring sheet in position.
]]B[[ VALVE SPRING INSTALLATION
Install the valve spring end with its identification color toward the spring retainer.
Identification color
Intake: Red
Exhaust: Green
]]C[[ RETAINER LOCK INSTALLATION
Using special tool MD998735, compress the valve spring and insert the retainer lock into position.
]]D[[ CYLINDER HEAD BOLT INSTALLATION
CAUTION: Attach the head bolt washer in the direction shown in the figure.
1. Tighten the bolts in the illustrated sequence two or three rounds.
Tightening torque: 45 ± 2 Nm (33 ± 1 ft-lb)
CAUTION:
^ When the tightening angle is smaller than the specified tightening angle, the appropriate tightening capacity cannot be secured.
^ When the tightening angle is larger than the specified tightening angle, remove the bolt to start from the beginning again according to the procedure.
2. Using the special tool MB991614, tighten the cylinder head bolt another 150°.
INSPECTION
CYLINDER HEAD
1. Check the cylinder head for water leakages, gas leakages, damages or cracks before cleaning.
2. Remove oil, water deposits, sealants, carbon deposits completely. Blow air after cleaning the oil passage to check whether the oil passage is not clogged.
3. Check the flatness of the lower surface of the cylinder head for distortions using a straight edge gauge and thickness gauge. Unless being within the limit, the distortion must be ground and corrected.
Standard value: 0.03 mm (0.0012 inch)
Limit: 0.05 mm (0.002 inch)
Cylinder head height (specification when new): 120 mm (4.7 inches)
CAUTION: *The grinding limit must be within 0.15 mm including the cylinder block.
Grinding limit: *0.15 mm (0.006 inch)
VALVE
1. Check the valve seat contact. 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:
Intake 1.0 mm (0.03 inch)
Exhaust 1.2 mm (0.04 inch)
Minimum limit:
Intake 0.5 mm (0.02 inch)
Exhaust 0.7 mm (0.03 inch)
3. Measure the valve's total length. If the measurement is less than the limit, replace the valve.
Standard value:
Intake 111.84 mm (4.403 inches)
Exhaust 114.04 mm (4.490 inches)
Minimum limit:
Intake 111.34 mm (4.384 inches)
Exhaust 113.54 mm (4.470 inches)
VALVE SPRING
1. Measure the free height of the spring. If it is less than the limit, replace.
Standard value:
Intake 59.15 mm (2.329 inches)
Exhaust 57.70 mm (2.272 inches)
Minimum limit:
Intake 58.15 mm (2.289 inches)
Exhaust 56.70 mm (2.232 inches)
2. Measure the squareness of the spring. If it exceeds the limit, replace.
Standard value: 2° or less
Limit: 4°
3. Valve spring load / installed height.
Standard value: 245.2 N (55.13 lb) / 49.2 mm (1.94 in)
VALVE GUIDE INSPECTION
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:
Intake 0.020 - 0.047 mm (0.0008 - 0.0018 inch)
Exhaust 0.035 - 0.062 mm (0.0014 - 0.0024 inch)
Limit:
Intake 0.10 mm (0.003 inch)
Exhaust 0.15 mm (0.005 inch)
VALVE GUIDE REPLACEMENT PROCEDURE
1. Using a press, remove the valve guide toward the cylinder block.
CAUTION: Do not install a valve guide of the same size again.
2. Rebore the valve guide hole of the cylinder head so that it fits the press-fitted oversize valve guide.
Valve guide hole diameters
0.05 oversize: 11.050 - 11.068 mm (0.4351 - 0.4357 inch)
0.25 oversize: 11.250 - 11.268 mm (0.4430 - 0.4436 inch)
0.50 oversize: 11.500 - 11.518 mm (0.4528 - 0.4535 inch)
3. Press-fit the valve guide until it projects by the specified amount.
Protrusion: 16.7 - 17.3 mm (0.66 - 0.68 inch)
NOTE: When press-fitting the valve guide, work from the cylinder head top surface.
NOTE: Pay attention to the difference in length of the valve guides. [Intake side: 45.5 mm (1.79 inches); exhaust side: 52.5 mm (2.07 inches)]
NOTE: After installing the valve guides, insert new valves in them to check for smooth operation.
VALVE SEAT INSPECTION
Assemble the valve, then measure the contact width. If the measurement exceeds the specified limit, replace the valve seat.
Standard value: 0.9 - 1.3 mm (0.04 - 0.05 inch)
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 diameters
0.3 oversize: 36.300 - 36.325 mm (1.4292 - 1.4301 inches)
Exhaust seat ring hole diameters
0.3 oversize: 32.300 - 32.325 mm (1.2717 - 1.2726 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 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.