Cylinder Head and Valves
This document has been updated per Mitsubishi TSB# 06-11-006CYLINDER HEAD AND VALVES
REMOVAL AND INSTALLATION
Removal Steps 1-22:
Required Special Tools:
* MB991999: Valve Stem Seal Installer
* MD998051: Cylinder Head Bolt Wrench
* MD998735: Valve Spring Compressor
* MD998772: Valve Spring Compressor
REMOVAL SERVICE POINTS
[[A]] CYLINDER HEAD BOLT REMOVAL
Use special tool MD998051 to loosen the cylinder head bolt.
[[B]] RETAINER LOCK REMOVAL
1. Using special tool MD998735 or MD998772, compress the spring.
2. Remove the retainer locks.
NOTE: Tag removed valves, springs and other components, noting their cylinder numbers and locations to facilitate reassembly. Store these components safely.
INSTALLATION SERVICE POINTS
]]A[[ VALVE STEM SEAL INSTALLATION
1. Install the valve spring seat.
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.
2. Using special tool M B991999, install a new stem seal to the valve guide.
]]B[[ VALVE SPRING INSTALLATION
Install the valve spring end with its identification color toward the spring retainer.
]]C[[ RETAINER LOCK INSTALLATION
Using special tool MD998735 or MD998772, compress the valve spring and insert the retainer lock into position.
NOTE: The valve spring, if excessively compressed, causes the bottom end of retainer to damage the stem seal.
]]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 in two or three steps.
Tightening torque: 108 ±5 m (80 ±4 ft-lb)
2. Back off the bolts once and tighten them again to the specified torque in step1.
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: 0.03 mm (0.0012 inch)
Limit: 0.2 mm (0.007 inch)
2. If the service limit is exceeded, correct to meet the specification.
Grinding limit: *0.2 mm (0.007 inch)
3. *If the service limit is exceeded, correct to meet the specification.
Cylinder head height (specification when new): 120 mm (4.7 inches)
VALVE
1. Check the valve face for correct contact. If incorrect, reface using a valve refacer. The valve should make a uniform contact with the seat at the center of the valve face.
2. If the margin exceeds the service minimum limit, replace the valve.
Standard value:
[Intake] 1.0 mm (0.04 inch)
[Exhaust] 1.2 mm (0.05 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 specified, replace the valve.
Standard value:
[Intake] 109.33 mm (4.304 inches)
[Exhaust] 113.50 mm (4.468 inches)
Minimum limit:
[Intake] 108.83 mm (4.285 inches)
[Exhaust] 113.00 mm (4.449 inches)
VALVE SPRINGS
1. Measure the free height of the spring and, if it is smaller than the minimum limit, replace the spring.
Standard value:
[Intake] 56.19 mm (2.212 inches)
[Exhaust] 53.30 mm (2.098 inches)
Limit:
[Intake] 55.19 mm (2.173 inches)
[Exhaust] 52.30 mm (2.059 inches)
2. Measure the squareness of the spring and, if the limit is exceeded, replace the spring.
Standard value: 2° or less
Limit: 4°
VALVE GUIDES
Measure the clearance between the valve guide and valve stem. If the limit is exceeded, replace the valve guide, valve, or both.
Standard value:
[Intake] 0.02-0.05 mm (0.0008-0.0019 inch)
[Exhaust] 0.04-0.06 mm (0.0016-0.0023 inch)
Limit:
[Intake] 0.10 mm (0.003 inch)
[Exhaust] 0.15 mm (0.005 inch)
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:
[Intake] 48.33 mm (1.903 inches)
[Exhaust] 50.70 mm (1.996 inches)
Limit:
[Intake] 48.83 mm (1.922 inches)
[Exhaust] 51.20 mm (2.016 inches)
VALVE SEAT RECONDITIONING PROCEDURE
CAUTION: Before correcting the valve seat, check the clearance between the valve guide and valve and, if necessary, replace the valve guide.
1. Using the special tool or a seat grinder, correct to obtain the specified seat width and angle.
2. After correcting the valve seat, lap the valve and valve seat using lapping compound. Then, check the valve stem projection.
VALVE SEAT REPLACEMENT PROCEDURE
CAUTION: Before replacing the valve seat, check the valve guide and, if necessary, replace the valve guide.
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.
Seat ring hole diameter:
Intake valve 0.3 oversize 37.80-37.83 mm (1.4882-1.4894 inches)
0.6 oversize 38.10-38.13 mm (1.5000-1.5012 inches)
Exhaust valve
0.3 oversize 34.80-34.83 mm (1.3701-1.3713 inches)
0.6 oversize 35.10-35.13 mm (1.3819-1.3831 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. 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 head gasket surface.
CAUTION: Do not install a valve guide of the same size again.
3. Re-bore 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 inch)
0.25 oversize 11.25-11.27 mm (0.4429-0.4437 inch)
0.50 oversize 11.50-11.52 mm (0.4528-0.4535 inch)
4. Install the new snap ring into the groove of exhaust valve guide.
5. Press-fit the valve guide until it protrudes 14 mm (0.55 inch) 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 sliding condition.